SUCCESSION

SUCCESSION , devolution of the deceased person's property on his legal heirs.

Order of Succession

The Pentateuchal source of the order of succession is "If a man die and have no son, then ye shall cause his inheritance to pass unto his daughter. And if he have no daughter, then ye shall give his inheritance unto his brethren. And if he have no brethren, then ye shall give his inheritance unto his father's brethren. And if his father have no brethren, then ye shall give his inheritance unto his kinsman that is next to him of his family and he shall possess it. And it shall be unto the children of Israel a statute of judgment, as the Lord commanded Moses" (Num. 27:8–11).

Scripture makes no mention of the father inheriting from his son but this is laid down in the Mishnah: "The father has precedence over all his offspring" (bb 8:2). An interpretation that son and daughter inherit like shares in their father's estate – and that Scripture merely indicates that daughters inherit all of the estate in the absence of sons – was raised and rejected in the Talmud (bb 110a–b) and it was confirmed that the daughter only inherits if there is no son (see below). A daughter succeeding to her father's estate was enjoined to marry "only into the family of the tribe of their father… So shall no inheritance of the children of Israel remove from tribe to tribe; for the children of Israel shall cleave everyone to the inheritance of the tribe of his fathers" (Num. 36:6–7; cf. also Philo, Spec. 2:126). In the Book of Tobit (6:10–11) two additional elements were attached to the above law: firstly, the enjoinder that the daughter marry "someone from a clan of her father's tribe" was interpreted as a duty imposed not only on a daughter upon her father's death, but also on the father – if he had no sons – to marry his daughter to one of his kinsmen; secondly, the father's violation of the enjoinder was treated as punishable by death, "according to the law of the Book of Moses" (ibid., 6:13). The sages of the Talmud laid down that the duty of the daughter to marry as above mentioned was applicable only to the particular generation to whom the enjoinder was directed (bb 120a and Rashbam ad loc.).

Jewish law has the parentelic system of succession, conferring the right of inheritance on all the kin of the deceased in the agnate (paternal) line of descendancy and ascendancy. Precedence among the heirs is determined, firstly, according to the degree of kinship with the deceased: the first parentela includes the deceased's children and their descendants, to the end of the line; the second includes the deceased's father and his descendants; the third, the father's father and his descendants; and so on in an ascending order – "that the estate may ultimately find its way to Reuben (the eldest son of the Patriarch Jacob)" (bb 8:2; tb, bb 115a–b). The nearer parentela takes precedence over and excludes more distant ones from the inheritance: "the lineal descendants of any one with a priority to succession take precedence" (bb 8:2).

The mother's family is not regarded as kin for the purposes of inheritance and therefore she does not inherit from her sons nor do her brothers or other relatives. Sons do, however, succeed to their mother's estate (bb 8:1). In post-talmudic times the mother too was recognized as a legal heir in a number of takkanot (see Gulak, Yesodei, 3 (1922), 94).

Relatives of the deceased, even if born out of wedlock or of an invalid marriage, are his kin and legal heirs for all purposes as if born of a valid marriage, except for the offspring of a bondswoman or a non-Jewess, who take the status of their mother and are not numbered among the father's family (Yev. 2:5; Sh. Ar., Ḥm 276:6).

"Inheritance in the Grave" (Yerushah ba-Kever)

According to this principle, the place of a son who predeceases his father is taken by his children in inheriting the portion which he, but for his death, would have inherited (bb 115a; Yad, Naḥalot, 1:3, 5). If the deceased's sole survivors should be a daughter and a son's daughter, the latter will inherit the whole estate since she takes the place of her father to the exclusion of his sister; the Sadducees, however, held the opinion that in such event the inheritance is shared between the deceased's daughter and his granddaughter (bb 115–116a). A son who predeceases his mother "does not inherit from his mother to transmit the [inheritance] to [his] brothers on his father's side" (bb 114b).

Primogeniture

The firstborn son of the father takes a double portion in his estate: "… he shall acknowledge the firstborn,… by giving him a double portion of all that he hath; for he is the firstfruits of his strength; the right of the firstborn is his" (Deut. 21:16–17). The firstborn is entitled to the double portion even if he is a *mamzer. On the other hand, the law of the firstborn does not apply to daughters who inherit in the absence of sons (Sif. Deut. 215). The firstborn only takes a double portion from the estate of his father and not from that of his mother or any other relative (Yad, Naḥalot, 2:8). If the firstborn predeceases his father, the double share which he would otherwise have inherited from his father's estate is taken by his heirs (Sh. Ar., Ḥm 277:15). If the firstborn is born after his father's death (or in the case of twins) he does not receive a double portion (bb 142b).

The inheritance due to the firstborn equals the portions of two ordinary heirs. Thus if the deceased is survived by five sons including the firstborn, the latter takes a third, i.e., two-sixths of the estate, and the other four heirs take one-sixth each; if there are nine sons, the firstborn takes a fifth and each of the others takes one-tenth (Yad, Naḥalot, 2:1).

The portion of the birthright is fixed according to the state of the inheritance at the time of its devolution. Hence it is neither diminished by the birth of another son after the father's death, nor is it increased by the subsequent death of a son (bb 142b). The firstborn only receives a double portion out of the muḥzakim, i.e., estate assets already held by the deceased in his possession at the time of his death. With regard to re'uyim, i.e., assets contingent to come to the deceased but not held by him at the time of his death, the firstborn takes only the share of an ordinary heir. Hence the firstborn does not take a double portion of an inheritance that accrues to his father after the latter's death, nor of the unrecovered debts owing by others to the latter – whether verbal or witnessed by deed. The firstborn does, however, take a double portion of all such outstanding debts owing to his father as were secured by pledges held by the latter in his possession at the time of his death (Bek. 8:9; Sh. Ar., Ḥm 278:7). Just as he takes a double portion, so the firstborn is obliged to defray a double portion of the outstanding debts owed by his deceased father (bb 124a).

The Husband as Heir to His Wife

The husband is heir to his wife and takes precedence over all her other heirs. Opinions are divided in the codes as to whether the husband's right to succeed to his wife's estate stems from the Pentateuchal or the rabbinical law (Yad, Naḥalot 1:8; Sh. Ar., eh 90:1 and Beit Shemu'el thereto, n. 1). The husband is heir to his wife even if their marriage was a prohibited one – as for example between a priest and a divorcee (Yad, Naḥalot 1:8) – provided only that they were still married to each other at the time of her death (Tur, eh 90). It does not matter that the husband was planning to divorce his wife, but if he had claimed that his marriage was based on a mistake, for example if he had raised a plea of blemish or defect on the part of his wife, he forfeits his right of inheritance (Teshuvot Maimoniyyot, Ishut, no. 35). In explaining this halakhah the aḥaronim expressed the opinion that although mere admission by the husband concerning his wife's defect does not suffice to dissolve their marriage, yet for the purposes of inheritance the husband's admission is like the testimony of 100 witnesses and therefore upon the death of the wife her husband will not be regarded as one who is heir to his wife's estate (Ḥelkat Meḥokek, eh 90, n. 15). According to some scholars, even a mored (see *Husband and Wife) or a husband who has refused to cohabit with his wife due to his vow, forfeits his right to inherit her estate (Rema, eh 90:5). The husband only inherits the part of his wife's estate in her possession at the time of her death and he does not take her place in inheriting her contingent inheritance (Sh. Ar., eh 90:1). If she became entitled to an inheritance during her lifetime but she died before gaining possession thereof, the inheritance will nevertheless be deemed to have been held by her and it will pass to her husband (Maharashdam, resp. eh no. 98).

The husband's right to inherit his wife's estate proved to be to the detriment of the wife's relatives and heirs since they received nothing at all from her estate. Various takkanot accordingly came to be made, aimed at defining the inheritance rights of the wife's heirs and limiting those of her husband. The first of these, dating from the mishnaic period, is known as the ketubbat benin dikhrin (i.e., ketubbah of male children). In terms thereof the husband inherited his wife's estate, but if the wife predeceased her husband leaving sons from the latter, these sons would upon their father's death inherit her ketubbah and dowry in addition to their portions in the estate of their father shared with his other sons. The object of the takkanah was "in order that all men might thereby be encouraged to give to a daughter as much as to a son" (Ket. 52b; Sh. Ar., eh 111), i.e., so that the father should not hesitate to give his daughter a large dowry since it would remain in the hands of his descendants and not with his daughter's husband. In geonic times the need for this takkanah fell away and it was abolished, since it had anyhow become customary for fathers to give more to their daughters (Tur, eh 111). Later many of the posekim sought to revive the validity of this takkanah but its abrogation was confirmed by Isserles (Rema, eh 111: 16).

In the period of the rishonim various takkanot were made to limit the husband's right to inherit his wife's estate. In some communities, if the wife died without issue, it became customary for the whole of the dowry given to her upon marriage to be inherited by her father or his heirs, and in other communities for the dowry to be divided between the husband and the wife's heirs on the paternal side (Sh. Ar., eh 118:19; Teshuvot Maimoniyyot, Ishut no. 35).

In France and Germany one of the ordinances known as the takkanat *Shum (שו״ם – Speyer, Worms, Mainz) came to be widely accepted. The effect thereof was to oblige the husband to return whatever remained of his wife's dowry – save for deduction of burial expenses – to the donor thereof or to her heirs, if she died childless within a year of her marriage; the second part of the ordinance laid down that upon the death of either husband or wife within the second year of their marriage, half of the dowry was to be returned to the heirs of the deceased if there were no surviving children (Rema, eh 52:4). In Spain similar takkanot were made. The most important of these, the takkanah of Toledo, laid down that if the wife was survived by her husband and any children of their marriage, her estate was to be shared equally between them; if there were no surviving children, her estate was to be divided between her husband and those who would have succeeded to her estate had she survived her husband. The object of the takkanah was to prevent the entire inheritance of the wife's family from going to her husband, and in this manner the scholars restricted the husband's rights as legal heir to his wife – in the opinion of some of the posekim even in accordance with the Pentateuchal law (see above) – and afforded him only one-half of her estate (Rosh, resp. 55:1,6; Rema, eh 118:8).

The Wife's Rights to Her Husband's Estate

The wife is not a legal heir to her husband's estate (bb 8:1) but has a number of rights which afford her a share therein and ensure provision for her sustenance and essential needs until her death or remarriage. The *widow receives from the estate her husband's ketubbah obligations, the *dowry increment, and her own property brought into the marriage and she is further entitled to maintenance from the husband's estate until her death or remarriage.

Important changes were introduced by the takkanot of Toledo and Molina with regard to the widow's rights to the estate of her deceased husband. These had the object of strengthening the hand of the husband's heirs against the widow's claims upon the estate, and laid down that if the husband was survived by any children the wife might claim no more than one-half of the total value of the estate toward payment of her dowry, ketubbah, and its increment. Thus the husband's heirs were afforded the option of settling the widow's claims in full – as was usually done when the total amount thereof did not exceed one-half of the estate – or settling her claims by paying her one-half of the value of the estate, even if less than due to her. If there were no children and the widow's claims were directed against the other heirs to her husband's estate, the latter would first return to her whatever remained – in specie, at the time of her husband's death – of the dowry she had brought him, and from the remainder of the estate she would recover her ketubbah and its increment in an amount not exceeding one-half of the value of the estate, the option as above mentioned again residing with the heirs (Rosh, resp. 50:9; Sh. Ar., eh 118:1; Beit Shemu'el ad loc. no. 1). In a takkanah of Castile it was laid down that a wife surviving her husband, without any children of their marriage, might take from the estate everything proved to have been brought by her as a dowry and remaining in specie at the time of her husband's death, and from the rest of the estate one-quarter, with three-quarters going to the husband's heirs (Rashba, resp., vol. 3, no. 432).

Inheritance Rights of Daughters

Since by law sons exclude daughters as heirs (see above), it became necessary to make provision for the support of daughters after the father's death. This was achieved by the scholars through an obligation imposed on the heirs of the deceased to maintain his daughters and by way of giving daughters part of the estate as a dowry.

maintenance of daughters

The rule is: "If a man died and left sons and daughters, and the property was great, the sons inherit and the daughters receive maintenance; but if the property was small, the daughters receive maintenance and the sons go a-begging" (Ket. 4:6; 13:3; 9:1). By mishnaic times this obligation had become part of the generally accepted law as a tenai bet din (i.e., a takkanah of the early scholars). Daughters are entitled to maintenance out of the estate of their deceased father until they reach the age of majority, or become betrothed (Ket. 4:11; 53b). Since the daughter's right to maintenance, as distinct from her right to a dowry, stems from the ketubbah deed (of her parents), any testamentary instruction of the deceased in deprivation of this right will have no legal validity (Ket. 68b; Sh. Ar., eh 112:10). Daughters only receive maintenance out of the estate of their deceased father if he is survived by sons as well; if the father is survived by daughters only, the latter share his estate – even though any of them be minors – and the question of their maintenance is no longer relevant (Sh. Ar., eh 112:18).

dowry

Sons are obliged to give their deceased father's daughters part of his estate as a dowry, as if the father were alive. This obligation is known as issur nekhasim (i.e., giving the daughter one-tenth of the estate), in terms whereof an assessment is made of what the father would have given his daughter as a dowry – according to his disposition, gathered from his friends and acquaintances, his transactions and standing – and if this cannot be established by the court, she is given one-tenth of the estate as the parnasat ha-bat (i.e., dowry; Sh. Ar., eh 113:1, based on Ket. 68a). According to some scholars, a daughter is also entitled to receive a dowry out of her deceased mother's estate (eh 113:1), but this is disputed by other scholars (Rema, eh 113:1). The father may deprive his daughter of a dowry by testamentary instruction since the parnasat ha-bat is merely an assessment of the father's disposition (Ket. 68b). Although the daughter's dowry is recoverable at the time of her marriage, the court may earlier decide on what she should be given upon her marriage (Beit Yosef and Darkhei Moshe, eh 113).

The dowry is regarded as a charge in favor of the daughter on the estate of her father, as at the time of his death, and she may seize from third parties any of the estate assets sold or mortgaged by her brothers. However, debts incurred by the deceased himself, as well as the obligations for the ketubbah of his widow and maintenance for the latter and her daughters, take preference over the daughters' dowry (Ket. 69a; Sh. Ar., eh 113: 5, 6).

See also *Parent and Child.

Shetar Ḥaẓi Zakhar

In post-talmudic times it became customary in the Ashkenazi communities for a father to allot to his daughter one-half of a son's share in his estate, for which purpose there was evolved a special deed known as the shetar ḥaẓi zakhar ("deed for half of the male child's share"). The deed was written by the father – and sometimes by the mother too (Naḥalot Shivah, no. 21, n. 1) – in favor of the daughter or her husband. It was generally written at the time of the daughter's marriage, the father undertaking to pay his daughter a specified sum of money, generally a very high amount, to fall due for payment one hour before his death, with a condition exempting his sons from liability for such debt after his death if they should give the daughter one-half of a son's share in his estate (Rema, Ḥm 281:7). This development was an important step toward the regulation of the daughters' right of inheritance in Jewish law (for further details see Assaf, bibl.).

Proselytes as Heirs

A proselyte is regarded as a newborn person whose ties of kinship with his family have been severed for inheritance purposes. The scholars ruled, however, that a proselyte may accept an inheritance from his gentile father, lest the loss thereof tempt him to return to his former ways. A proselyte's estate is inherited by sons born after his conversion to the exclusion of his other sons, whether or not proselytized along with himself (Kid. 17b; bb 142a). The estate of a proselyte who dies without any legal heirs may be acquired in the same way as abandoned property, by the firstcomer, who is regarded as an heir for the purposes of estate liabilities in favor of third parties (Rema, Ḥm 275:28).

Devolution of Inheritance and Renunciation

Upon death the estate passes automatically and immediately into the ownership of the heirs. Hence an heir cannot renounce his share by waiver thereof, since in Jewish law a person cannot waive something that already belongs to him but only that which is yet to come to him, and the heir can only transfer his share in the same way as any other property is transferred through one of the recognized modes for its assignment or alienation (see *Acquisition, Modes of). An exception to this rule is the birthright portion of the firstborn (see above), as distinguished from his ordinary share (Tur, Ḥm 278; Sh. Ar.; Ḥm 278:10). An heir may, however, abandon his share in the same way as he abandons any of his own property (Sma, Ḥm 278, no. 27) and a husband's renunciation of his right to his wife's estate is valid if made prior to their marriage, but not thereafter (Ket. 9:1, 83a).

Debts of the Deceased

It is a mitzvah for the heirs of the deceased to pay his debts. They will be compelled to do so if they inherit land and, according to a takkanah of the geonim, the creditor may recover from the heirs even when they inherit movable property. If they inherit both, the heirs prevail if they want payment to be made out of the land rather than the movable property as desired by the creditor (Sh. Ar., Ḥm 107:1). For the purposes of her dowry (see above) a daughter takes only from the land left by the deceased, a rule that survived the above-mentioned takkanah of the geonim (Sh. Ar., eh 113:2).

Payment is always recovered from the poorest quality land (i.e., ẓibburit, Sh. Ar., Ḥm 108:18). A stipulation by the creditor to recover payment out of the debtor's best (iddit) or medium (beinonit) land is not binding on the latter's heirs unless this was expressly provided for in the stipulation (ibid.; see also *Execution). If the heirs of the deceased inherit nothing from him, they will not be obliged – not even morally – to defray his debts, since they do not have to do so out of their own property (Sh. Ar., Ḥm 107:17). An heir is not heard if he should plead, "I do not take nor will I pay" (Rema, Ḥm 107:1; and Sh. Ar., Ḥm 278:10). The heirs are liable for debts of the deceased to the extent that these do not exceed the value of the assets held by the deceased at the time of devolution of the inheritance, his contingent assets (re'uyim) being excluded for this purpose (Rema, Ḥm 104:16). However, a debt due to the deceased is considered part of the assets held by him at the time of his death. Some scholars have explained this special rule on the basis of the extensive development that took place with regard to credit transactions, with creditors coming to rely upon such as upon movable property rather than as contingent assets (Rosh, resp. 36:3), and other scholars have regarded loans due to the deceased as property held by him upon death since the money of the loan had previously been in his possession (Beit Shemu'el, eh 100, no. 3).

The creditor recovers his debt from each of the heirs on a pro-rata basis (Tos. to bb 107a S.V. u-va ba'al ḥov). A field hypothecated (see *Lien) by the deceased is recovered by the mortgagee from the heir who receives it as part of his share, and he may recoup from the remaining heirs (Sh. Ar., Ḥm 175:4). Similarly, if a creditor should experience difficulty when seeking to recover a proportionate share of the debt from each of the heirs, he may recover the whole debt out of the share of any one of them, and that one may recoup from the others (Rosh, resp. 79:7).

A verbal debt (see *Obligations, Law of) is not recoverable from the heirs of the debtor except in the following cases: the debtor had before his death and from his sickbed admitted such indebtedness; the loan was for a fixed period and not yet due for payment; or the debtor had refused to make payment notwithstanding a judgment of the court, maintaining his refusal until death. In each of these three cases the creditor recovers without swearing an oath (Sh. Ar., Ḥm 108:11). A debt witnessed by deed is only recoverable after the creditor has sworn that the debt is still outstanding (Sh. At., Ḥm 108:17). If the heir should plead that he was left no property by the deceased and the creditor plead with certainty that the deceased did leave property, the heir will be exempted from liability upon taking the equitable *oath (shevu'at hesset; Sh. Ar., Ḥm 107:2). A creditor holding a bond of indebtedness with a credency (ne'emanut) clause in his favor (see *Shetar) will not be exempted from delivering an oath when seeking to recover from the debtor's heirs unless he was so exempted expressly with reference to the debtor and his heirs (Sh. Ar., Ḥm 71:14–17). In case of a similar clause in favor of the debtor with regard to a plea of payment of the bond, the creditor will not be entitled to recover from the former's heirs on such bond (Sh. Ar., Ḥm 71:21).

Debts of the deceased are not recoverable from his heirs as long as they are minors regardless of any clause whatever stipulated in the bond of indebtedness, lest contradictory evidence come to light (ibid., 108:3). However, in the three events mentioned above in which a verbal debt of the deceased is recoverable from his heirs, his debts will be recoverable from the minor orphans too (ibid.). The court has the discretion to allow debts to be recovered from the minor orphans if this be to their advantage, e.g., because the creditor is prepared to waive part of the debt in return for recovering the balance forthwith (Rema, Ḥm 110:1), and the minor heirs may also be recovered from when they are liable to a penalty for nonpayment on due date (Siftei Kohen, Ḥm 110, no. 3). If some of the heirs are majors the creditor recovers from them pro-rata to their share in the estate. For the purpose of division of the estate the court will appoint a guardian for the minor (Sh. Ar., Ḥm 110:1).

Commorientes

Where two persons die at or about the same time and it is unknown who died first, the rights of their heirs are determined in accordance with the following order of priority: If one of the claimants is a "certain" heir – i.e., whatever the sequence of the deaths – and the other a "doubtful" heir – i.e., only upon a particular sequence of death – the former claimant excludes the latter and takes all (Rashbam, bb 158b); if both claimants are doubtful heirs they take equal shares of the inheritance (Yev. 38a; Yad, Naḥalot 5:5); if one of the claimants is kin to the deceased himself and the other has become entitled through the death of a relative who is kin to the deceased, the former claimant takes all in both cases (Yad, Naḥalot 5:6), for the reason that the inheritance is not to be diverted from the kin of the deceased unless this is warranted by proof of a particular sequence of deaths (see M. Silberg, Ha-Ma'amad ha-Ishi be-Yisrael (1965), 314–22).

On the inheritance of public offices, see *Mishpat Ivri; *Public Authority; on the inheritance rights of apostates, see *Apostasy (Family Law).

In the State of Israel

Matters of inheritance are governed by the Succession Law, 5725 – 1965, the provisions whereof accord with Jewish law in a number of respects and digress therefrom in others. Thus, as in Jewish law, the law lays down, inter alia, that children born out of wedlock and even mamzerim are included among the heirs (sec. 3 (c)). The Jewish law principles with reference to commorientes (see above) were adopted virtually without change. On the other hand the law differs from the traditional approach in laying down that the line of succession ends with the grandparents and their descendants, whereafter the state succeeds, and that both husband and wife are in the line of succession to each other. So too the law recognizes no distinction between sons and daughters, between the paternal and maternal lines (sec. 10), nor does it mention the double portion of the firstborn. (On the question of the absorption of Jewish law in these matters, see Elon, bibl.). An important principle incorporated in the law is that of the widow's right to maintenance out of the estate; unlike Jewish law, this right is extended to other relatives of the deceased besides the widow and daughter, and is also wider in scope (secs. 57, 58).

See also *Apotropos; *Wills.

[Shmuel Shilo]

In the Regulations of the Chief Rabbinate of Israel

In 1943 the first steps were taken to promulgate regulations by the Chief Rabbinate to provide for equal distribution of a decedent's estate between sons and daughters, and between husband and wife. The Mandatory Succession Ordinance of 1923 provided that, where a person died intestate, and owned land classified as miri at the time of his death, the provisions of the Ordinance – mandating an equal distribution to sons and daughters, to the man and the woman – were binding upon the religious courts as well. The Israeli rabbinical courts complied with this Ordinance, but it was difficult to anchor this custom in the rule of dina de'malkhuta dina (see *Dina de-Malkhuta Dina), insofar the majority of halakhic decisors ruled that dina de-malkhuta dina does not apply to matters of inheritance. Thus, the rabbinical courts adopted an approach whereby the equal distribution was carried out on the basis of the agreement of both parties, entered into with a kinyan, to distribute the estate in a manner differing from the manner prescribed by Torah. (The rabbinical courts act in this fashion today as well, unless the parties have agreed that the rabbinical court adjudicate according to the rules set forth in Torah, pursuant to Section 155 of the Succession Law.)

In 1943, regulations were enacted setting forth the procedural rules in the rabbinic courts. Sections 182 and 183 of the regulations provide that, regarding miri land – the rabbinic court is to rule pursuant to the Succession Ordinance. Thus, the rabbinical courts accepted the regulations set forth in the Succession ordinance regarding certain portions of the inheritance as binding upon the parties by force of the Chief Rabbinate's regulations, and not only by force of rabbinical acquiescence de facto to an arrangement based on an authority external to the rabbinical court. However, the incorporation provisions of the Succession ordinance should not be understood as a halakhic-normative provision that henceforth, Jewish Law mandates equal rights in the distribution of an estate between the sons and the daughters, and husbands and wives – i.e. as a substantive change in the laws of succession in Jewish law.

An attempt to make that substantive change in Jewish Law was made by Chief Rabbi Isaac Herzog in the years preceding the establishment of the State of Israel, and in the first years thereafter. Rabbi Herzog proposed that the Chief Rabbinate, together with the other prominent rabbis of that generation, should enact regulations regarding inheritance to provide for equal distribution of the inheritance between sons and daughters. His suggestion was that, at the time of the parents' marriage, a condition should be written in the ketubbah stating that the distribution of the "estate" (and not "the inheritance") be carried out in such a manner that the daughter would "receive" (and not "inherit") an equal share with the son, so long as she is unmarried, rather than only a tenth of the assets. Rabbi Herzog assumed that, if such regulations were enacted, the rabbinic courts would be conferred jurisdiction to adjudicate matters of inheritance, whereas without such regulations – and insofar as the rabbinic courts would rule according to the Shulḥan Arukh – the Knesset would revoke the jurisdiction of the rabbinical courts over this issue and possibly over other issues relating to personal status. Rabbi Herzog hoped that, after promulgating these enactments, it would be possible to introduce a legislative proposal before the Knesset for the enactment of a Succession Law based on Jewish law. Beyond these considerations, Rabbi Herzog believed that such enactments were necessary as a substantive matter as well, just as he believed that enactments (takkanot) should be promulgated in many other areas. In view of the changes that had occurred in society over the course of time, as a result of which women were insisting upon their rights and demanding equality, it was the duty of the rabbinate to make efforts to find a solution that would address the feelings of women that they were discriminated against by Jewish Law. Rabbi Herzog proposed the promulgation of similar enactments regarding the inheritance of the eldest son and the inheritance by the husband of his wife's holdings. It should be emphasized that his proposals were based on halakhically acceptable measures and earlier regulations that had been promulgated in these matters.

Like Rabbi Herzog, Rabbi Ben Zion Meir Ḥai Ouziel, his Sephardi counterpart in the Chief Rabbinate, believed that equal distribution of the parents' property among sons and daughters could be provided for at the time of the marriage of the parents, through a will. Rabbi Herzog's proposals for rabbinical enactments were not accepted by the other members of the Chief Rabbinate Council, and the proposed enactments never proceeded beyond the "proposal" stage.

Regulations Promulgated by the Moroccan Sages in the Mid-Twentieth Century

In the 1950s, proposals were raised before the Rabbinical Council of Morocco, regarding the promulgation of regulations to equate the status of daughters and sons. The reasons invoked by the Moroccan sages to justify such regulations were the changes that had occurred over time in the general outlook and in the situation, status and role of women, which was equal to that of men in the workplace and in terms of earning a livelihood. The regulatory proposal included a grant of equality to married women as well as unmarried women, representing a novel approach in comparison to the regulations that had been promulgated throughout the ages in this regard. These proposals were never promulgated as regulations, because shortly after this proposal was raised, Morocco gained political independence and the rabbinic courts' jurisdiction over questions of personal status was revoked. Nevertheless, these proposals of the Moroccan Rabbinical Council are instructive regarding the approach of the North African sages to the promulgation of regulations in our time, as opposed to the stricter approach, limiting halakhic creativity, adopted by the Ashkenazi sages since the time of the Emancipation in Europe (see *Takkanot).

[Menachem Elon (2^nd ed.)]

bibliography:

I.M. Hazan, Successione per Israele (1851); H.B. Fassel, Das mosaisch-rabbinische Civilrecht, 1 (1852), 274–320; A. Wolff, Das juedische Erbrecht (1888); M. Bloch, Das mosaischtalmudische Erbrecht (1890); I.S. Zuri, Mishpat ha-Talmud, 3 (1921), 1–24; Gulak, Yesodei, 3 (1922), 71–112; Ch. Tchernowitz, in: Jewish Studies… I. Abrahams (1927), 402–15; S. Assaf, in: Emet le-Ya'akov, Sefer Yovel… J. Freimann (1937), 8–13 (Heb. section); Ch. Cohen, in: Yavneh, 3 (1948/49), 80–83; J.D. Cohen, in: Ha-Torah ve-ha-Medinah, 2 (1949/50), 18–24; B.M.H. Ouziel, ibid., 9–17; et, 2 (1949), 16–20; 5 (1953), 152–6; 6 (1954), 279–82; 9 (1959), 536–42; A. Karlin, in: Ha-Peraklit, 9 (1952/53), 22–26; J. Hakohen, in: Ha-Torah ve-ha-Medinah, 5–6 (1952/54), 177–90; B.M.H. Ouziel, in: Talpioth, 5 (1952), 451–74; 6 (1953), 51–64; J. Herzog, ibid., 6 (1953), 36–50; A. Karlin, Divrei Mishpat, 1 (1954) (Dinei Yerushot ve-Ẓavva'ot); S.D. Revital, in: Sugyot Nivharot be-Mishpat (1958), 442–69; E.J. Waldenburg, in: Sefer Yovel le-Shimon Federbusch (1960), 221–6; Elon, Mafte'ah, 92–104; E.E. Ur-bach, in: Divrei ha-Congress ha-Olami ha-Revi'i le-Madda'ei ha-Yahadut, 1 (1967), 133–41; Engl. summary: ibid., 263 (Eng. section); B. Schereschewsky, Dinei Mishpahah (1967²), 224–70; M. Elon, in: ilr, 4 (1969), 126–40. add. bibliography: M. Elon, Ha-Mishpat ha-Ivri (1988), 1:135, 474f, 670ff., 679ff.; 3:1337f., 1362, 1389, 1413ff. and index; idem, Jewish Law (1994), 1:152; 2:578, 828f., 837ff.; 3:1596f., 1625, 1656, 1683ff.; idem, Ma'amad ha-Ishah (2005), 255–96; idem, Ḥakikah Datit (1968), 42–43; idem, "Yiḥuda shel Halakhah ve-Ḥevrah be-Yahadut Ẓefon Afrikah mi-le-aḥar Gerush Sefarad ve-ad Yameinu," in: M. Bar Yuda (ed.), Halakhah u-Petiḥut Ḥakhmei Moroko ke-Posekim le-Doreinu (1985), 29ff.; M. Elon and B. Lifshitz, Mafte'aḥ ha-She'elot ve-ha-Teshuvot shel Ḥakhmei Sefarad u-Ẓefon Afrikah (legal digest) (1986), 169–73; B. Lifshitz and E. Shochetman, Mafte'aḥ ha-She'elot veha-Teshuvot shel Ḥakhmei Ashkenaz, Ẓarefat ve-Italyah (legal digest) (1997), 110–15; Y. Cohen, "The Inheritance of a Wife of her Husband in the Communal Enactments," in: Shenaton ha-Mishpat ha-Ivri, 6–7 (1979–1980), 133–75 (Heb.); I. Gruenfeld, The Jewish Law of Inheritance (1987); Y. Herzog, in: I. Warhaftig (ed.), Teḥukah le-Yisrael al-pi ha-Torah, 2 (1989); Y. Rivlin, Ha-Yerushah ve-ha-Ẓavva'ah ba-Mishpat ha-Ivri (1999); E. Shochetman, "The Halakhah 's Recognition of the Laws of the State of Israel," in: Shenaton ha-Misphat ha-Ivri, 16–17 (1991), 417 (Heb.); Z. Weinman, "Law of Inheritance in the Rabbinical Courts – Applied Halakhah," in: Shenaton ha-Mishpat ha-Ivri, 8 (1981), 490ff. (Heb.).

SUCCESSION

The issue of succession—the assumption by a person of political or other institutional authority previously possessed by another—entered Islam with the death of the prophet Muhammad and has been a subject of continuous debate ever since. Simply put, Sunni Muslims believe that the Prophet's religious authority died with him, that his political authority passed to a succession of caliphs initially selected on the basis of consensus and merit, and that the institution of the caliphate rapidly declined into hereditary monarchy and ultimately military usurpation. Shi˓ites believe that both the Prophet's religious and political authority remained united in a hereditary line of imams, that his dying wishes were subverted and suppressed by Sunnis, and that the caliphal succession has never been legitimate. Recently, scholars have increasingly questioned the traditional Muslim view of both the theory and the practice of caliphal succession. Some have argued that the historical record is obscure on even the most crucial points, and that in any case what can be gleaned from it suggests that divine absolutism, primogeniture, and forcible seizure of power were present from the beginning. Others have stressed the contributions of pre-Islamic Middle Eastern political traditions—particularly that of Persian/Zoroastrian divine absolutism—to the development of Islamic political theory. Whatever the exact course of events, it is clear that "the classical theory of the caliphate" as formulated by al-Mawardi (d. 1058) was the culmination of an ongoing process of interaction between the Islamic religious and political establishments. Subsequently, Muslim thinkers who strove to preserve an Islamic component in political succession were forced into increasingly distressing compromises by such cataclysms as the Mongol destruction of the Baghdad caliphate, the advent of secular dynastic rule in most Muslim lands, and the increasing intervention in Middle Eastern politics by European imperialism. After the dismantling of the Ottoman Empire following the First World War, most governments in Muslim lands adopted modern secular principles of political legitimacy, although by the end of the twentieth century, popular support for the reinstatement of Islamic principles and practices of political succession was increasing.

Etymology of Khalifa

The original significance of the Arabic verb for "to succeed," kh-l-f—from which is derived the word for caliph (khalifa)—is irretrievably buried beneath ancient and impenetrable layers of usage. It occurs in Akkadian meaning "to slip into or put on [especially clothes]" and in Hebrew meaning "to succeed, replace or pass away." Dictionaries of early South Arabic give one occurrence of the word khalifa with the quasi-political meaning of "viceroy" in a fourth-century South Arabic inscription, but also give meanings as diverse as "suit of clothes," "gate of a city," and—happily confirming a popular conception about Arabic etymology—"pregnant camel." It is a sign of the ambiguity of the meaning of the word that, although in both Arabic and Hebrew the first form of the root commonly denotes succession in time, place, or function, it has come in the former to be applied to the thing succeeding and in the latter to the thing succeeded. Lane's Arabic-English Lexicon gives the primary meaning of the verb khalafa as "he came after, followed, succeeded, or remained after, another, or another that had perished and died." Of the 127 instances of the root kh-l-f in the Qur˒an, most have specialized meanings related only distantly to the first form meaning of "to come behind or after." As demonstrated by al-Qadi, the array of meanings encompassed by kh-l-f and its derivatives is closely paralleled by the array of meanings encompassed by b-d-l, which can mean both "to exchange" and "to be exchanged" and is used by the Qur˒an in contexts closely analogous to those in which it uses kh-l-f. The near identity of these two roots is echoed today in the use by modern Arabic and Hebrew of badla and khalifah, respectively, to denote "suit"—that is, change of clothes.

The Term "Khalifa" in the Qur˒an

The etymological significance of the word khalifa in the Qur˒an is less obscure than its pre-Qur˒anic usage because the Qur˒an has been an object of philological exegesis since very early after its appearance. The two plural forms khulafa˒ and khala˒if occur seven times between them in the Qur˒an, and in all cases are said by commentators to denote tribes or peoples who, despite the warnings of their apostles, disobeyed God's will and were consequently wiped off the face of the earth by Him. Most commentators similarly treat the two occurrences of the singular khalifa as referring to the classic Qur˒anic theme of a succession of peoples governing the earth, rather than the succession of individual rulers governing peoples. However, a handful of interpretations of Qur˒an 2:30—"When your Lord said to the angels: I am about to put a successor (khalifa) on the earth, they said: Will You place on it one who will do harm on it and will shed blood ..."—interpret the word khalifa as a reference to Adam as an individual rather than the Children of Adam as a collective. The scarcity and lateness of commentators who ascribe to the word khalifa the connotation of an individual person with a political office have suggested to some scholars that the connection between the Qur˒an's term khalifa and the office of caliphate was not made "before the end of the Umayyad period or the early decades of Abbasid rule" (al-Qadi, "The Term Khalifa"). To others it implied that the idea of a connection was in the air but played down by early commentators "anxious to avoid approving the Umayyad caliphs' use of the verse about Adam to enhance their own dignity" (Watt 1971, p. 567).

Umayyad Succession

The role of religion in the Umayyads' justification of their succession to the caliphate has itself undergone substantial revision by scholars—a revision that parallels revisionist views of the progress of both empire and theocracy in the early Islamic state generally. The Umayyads' use of the title khalifat Allah—"Caliph of God" (denoting a direct connection to the Divine) as opposed to "Caliph of the Apostle of God" (denoting succession to Muhammad as political leader of the umma)—belies the conventional picture of the entire Umayyad period as an interval of secular kingship between the perfect theocracy of the Rashidun and the less perfect theocracy of the Abbasids. ˓Umar II's reprise of Abu Bakr's humble declaration that "I am not khalifat Allah" was the exception rather than the rule. The sources abound in evidence of a concerted effort by Umayyad court poets and scribes to augment the initial Umayyad claim to the caliphate as avengers of the blood of ˓Uthman with the claim that they had been installed in their position by God. Crone and Hinds rely heavily on this court poetry to reverse the traditional view of the emergence of divine absolutism in Islam. They argue that the theocratic Shi˓ite-type conception of the imamate was the original one and that from the very first, caliphs aspired to as much, if not more, religious authority than the Prophet. It can be plausibly argued either that the interpretation of the title khalifat Allah by the Umayyads constituted "the first formulated 'theory' of the caliphate in Islamic history" (al-Qadi, "The Religious Foundation of Late Umayyad Ideology and Practice") or that the Umayyads "had still not decided to transfer the concept of 'Caliph of God' from the sphere of court flattery and rhetorical salutation into the sphere of law" (Barthold).

Early Islamic Sectarianism and Caliphal Succession

If the precise etymology of the caliphal title and the exact nature of the ideological basis on which the Umayyads justified their succession are matters of speculation, the fact that the air was thick with theological ferment surrounding the issue of political succession in the umma throughout the Umayyad period is not. Sectarianism in any religion often has thinly disguised political roots, but because of Islam's status as a state religion from its inception, the political roots of early Islamic sectarianism are not disguised at all. The three broad non-Shi˓ite sectarian subdivisions of the earliest period—Kharijite, Qadarite, and Murji˒ite—all contained parallel theological and political components—that is to say, doctrinal positions on sin that very closely allied with conceptions of legitimate political succession. The Kharijite doctrine that any sin renders the sinner an apostate had its political reflection in their position that any injustice on the part of the caliph renders his succession invalid. The Qadarite doctrine that humans possess control over (qadar) and therefore responsibility for their actions had its political reflection in their position that the legitimacy of the caliph's succession depended on his dispensing equitable justice to the ruled. The Murji˒ite doctrine that judgment of any sinner must be deferred to God had its political reflection in their view that the legitimacy of caliphal succession was the concern of God rather than men. While Kharijite anarchism and Qadarite activism were persecuted under the Umayyads, Murji˒ite quietism seems to have been the political ideology of choice for the silent majority during the Umayyad caliphate. In contrast to the supposed period of Rashidun harmony during which no fewer than three of the first four caliphs were felled by assassins, not one of the Umayyad caliphs–with the sole exception of the battlefield death of Sulayman b ˓Abd al-Malik—ended his term of office for any reason other than death by natural causes until al-Walid II was edged out by Yazid III in 744 after the Abbasid revolution had already begun.

Hadiths About Caliphal Succession

It is against this background of political and theological ferment that hadith statements about caliphal succession attributed to the Prophet must be evaluated. In contrast to the dearth of explicit statements in the Qur˒an about legitimate political succession, hadith literature has many explicit references to the caliphate as a political office. Many of these hadiths use the terms imam or emir rather than khalifa in some or all variants, leaving open the possibility that they might have been initially uttered by the Prophet in reference to following the leader of the communal prayer and obeying the commanders of early military expedition, and were later reinterpreted—willfully or not, and with or without substitution of the word khalifa—as allusions to a political institution that did not exist prior to the Prophet's death. Those hadiths which refer unambiguously to the caliphate reflect debates about the political succession in Islam going on among early Muslim intellectuals who wrote down the record of the Prophet's utterances and the history of the early exemplary Rashidun (rightly guided) caliphate centuries after the fact. A vast majority of approved hadiths about caliphal succession fall into the quietist Muji˒ite rather than the radical Kharijite or activist Qadarite category.

The question of whether the caliph's full title was properly khalifat Rasul Allah, ("the successor of the Apostle of God"), with the connotation of succeeding the Prophet in his temporal function as defender of the faith, or khalifat Allah ("the successor of God"), with the connotation of being appointed by and having a direct connection with God Himself, was also a much-vexed and obscure issue of early Islamic political discourse. The uneasiness of Sunni orthodoxy with the latter title and its accompanying conception of the caliph as possessor of the type of divine charisma claimed for the Shi˓ite imams is reflected by the widely circulated stories about the first caliph Abu Bakr's insistence on being called khalifat Rasul Allah rather than khalifat Allah. The second caliph ˓Umar rejected both khalifat Allah as applying only to King David and khalifat Rasul Allah as applying only to Abu Bakr and decided that the correct title was "Caliph of the Caliph of the Apostle of God." In view of the potential of this title for cumbersome recursiveness, ˓Umar opted for amir al-mu˒minin ("Commander of the Faithful"), a title that continued to have a rarified status even after the title khalifa became debased in the late Middle Ages through widespread usage by many different rulers of widely varying power and piety.

Caliphal Succession Under the Abbasids

As is attested to by the survival of hadith expressing some of their views in the standard Sunni collections, aspects of the Khariji, Qadari, and Murji˒ite approaches all fell within the boundaries of what later became the Sunni discourse on the legitimacy of caliphal succession. But it was slogans borrowed from ˓Alid groups later consigned by the heresiologists to the moderate but nonetheless heretical fringes of Shi˓ism that swept the Abbasids into office. The Abbasids borrowed three planks from the ˓Alid platform. First of all, they claimed the right to caliphal succession as members of the house of Muhammad (ahl al-bayt) by virtue of their eponymous ancestor's having been the uncle of the Prophet. Secondly, they claimed to be the beneficiaries of nass—designation by virtue of the father of the first Abbasid caliph's having had the imami charisma transferred to him by the son of Muhammad b. al-Hanafiyya, the reluctant figurehead of the revolt of al-Mukhtar which had first put both the mawali constituency and their ˓Alid ideology on the Islamic political map. Thirdly, they claimed to be rightful caliphs by virtue of being the members of the family of Muhammad (Al Muhammad) most capable of achieving power. The first two of these claims were shaky to say the least. While it is true that in terms of genealogy al-˓Abbas was on the right side of the ˓Abd Manaf family tree relative to Umayya, he had not even converted to Islam during Muhammad's lifetime, and was certainly not the relative of the Prophet whom the ˓Alids had in mind when they chanted the slogan "most pleasing of the house of Muhammad." The alleged transfer of imami charisma to the father of al-Saffah by the son of Ibn al-Hanafiyya had all the plausibility of the Donation of Constantine employed a half century later to justify papal dominion in Western Europe. The third justification of the Abbasid succession—that the Abbasids were the members of the family of the Prophet most capable of achieving power—was rendered unassailable by the successful result of the Abbasid revolution.

The early Abbasid era, in addition to being the golden age of the Baghdad caliphate, was also the period during which the embryonic Sunni Islam defined its approach to legitimate caliphal succession—frequently in opposition to the vision of the reigning caliph. The view favored by the caliphs is represented by the Risala fi al-Sahaba of Ibn al-Muqaffa˓ (d. 756), which advises the caliph al-Mansur (r. 754–775) to aspire to be something like the high priest of Islam and act as the final arbiter on points of Islamic law. The view favored by the "proto-Sunni" ulema was represented by the qadi (judge) Abu Yusuf, who in his Kitab al-Kharaj advises the caliph Harun al-Rashid (r. 786–809) to subordinate his will to the stricture of the book and the sunna like any other Muslim. The issue was decided by the outcome of the mihna, or "Islamic Inquisition" (833–847), during which Ahmad b. Hanbal's (d. 855) heroic opposition to the caliphal government's efforts to enforce adherence to the Mu˓tazilite doctrine of the createdness of the Qur˒an upheld the ascendance of the book and the sunna over the will of the caliph of the day. This triumph of the emerging Sunni approach to caliphal legitimacy resulted in the dispersal of religious authority away from a central governing body and toward multiple schools of law and a decentralized clerical authority. In retrospect, this separation between Islam and the state insured that Islam would avoid the fate of Zoroastrianism, the official religion of Iraq-based, Middle East-wide, divine-absolutist Sassanian Empire to which the Abbasid caliph was successor, and develop into a supranational world religion that was able to survive the demise of the first Islamic state.

The Classical Theory of the Caliphate

It is one of the oft-noted paradoxes of Islamic intellectual history that the theory of caliphal succession was explicitly formulated just at the time when the institution of the caliphate was declining into political insignificance. But it is precisely in weakness that political institutions are in need of theoretical bolstering. The fullest expression of the classical theory of the caliphate was articulated by al-Mawardi (d. 1058), whose Ahkam al-sultaniyya (Rules of sovereign power) defines the relationship between the caliph's spiritual and temporal duties, noting that the "imamate is established for the succession of prophecy in the preservation of the religion (din) and the administration of the world (dunya)."

The necessity of the caliphate as a collective religious duty (fard kifaya) upon the Islamic community is demonstrated through such shari˓a evidence as hadiths enjoining obedience to the imams, the ijma˓ (consensus) of the community about establishing an imam. Traces of the polemic against Shi˓ism that conditioned the formulation of the embryonic theories of caliphal succession of al-Mawardi's predecessors—for example, the Ash˓arite theologians al-Baqillani (d. 1013) and al-Baghdadi (d. 1037)—surface only rarely in al-Mawardi's exposition. The awkward position into which Sunni theorists of the caliphate were squeezed by the need to defend the historical record of the caliphate, on the one hand, and the need to oppose Shi˓ite theocratic conceptions of political succession, on the other is illustrated by al-Mawardi's insistence that, while the caliph should be selected by election, rather than appointment, and this election can be accomplished by a single elector—this last provision justifying what became the most common mode of succession, appointment by a caliph of his son as heir. Al-Mawardi is careful to refer to this mode of succession as ˓ahd ("investiture") rather than with the Shi˓ite term nass ("designation"). Similarly, the principle of imamat al-mafdul ("the imamate of the less qualified") does double duty for al-Mawardi. It serves as a rejection of the Kharijite stance that as soon as a better qualified candidate appeared he must replace a less qualified sitting caliph no matter how much civil disturbance this might cause; it also counters Shi˓ite claims that the successions of the first three caliphs were illegitimate because ˓Ali—who even by most Sunni accounts was a more qualified candidate than ˓Uthman—was passed over. For all his will-ingness to compromise on the person of the caliph, al-Mawardi strives at every point to uphold the sanctity of the caliphal succession itself. Despite the many principles of caliphal succession that he draws by analogy with shari˓a contracts, al-Mawardi stresses that the caliphal bay˓a is "a public interest whose consequences go beyond that of private contracts" (al-Mawardi, al-Akham al-sultaniyya, p. 9).

As the caliphate progressively declined into powerlessness and caliphal succession eventually became the plaything of the sultan of the moment, al-Mawardi's successors were forced into a progressively more realistic accommodation with historical actuality. Al-Ghazali (d. 1111), for example, adds to election and investiture by the preceding caliph a third mode of succession: investiture by a man of power (rajul dhu shawka). As he reluctantly concedes: "Government in these days is a consequence solely of military power, and whosoever he may be to whom the possessor of military power gives his allegiance, that person is the caliph. " (Al-Ghazali, Ihya˒ ˓ulum al-din)

Succession after the Caliphate

After the Mongol conquests obliterated the Baghdad caliphate, the terms in which men of religion evaluated the legitimacy of political succession diverged still further from al-Mawardi's "classical" theory. Two different approaches to a world without a caliph are represented by Ibn Taymiyya (d. 1328) and al-Taftazani (d. 1389). Ibn Taymiyya's theory of the caliphate can best be characterized as a revival of Kharijite positions. He abandons the Quraysh lineage requirement, the imamate of the less qualified, and even the necessity of the caliphate itself. Ibn Taymiyya seems to regard excessive stress on the importance of even the Sunni imamate as a Shi˓ite-like heresy and is as antipathetic to Sunni consensus as to imami charisma as a religious principle of legitimate political succession. For Ibn Taymiyya, good Islamic government is any state in which emirs and ulema collaborate in the interests of Islam.

Al-Taftazani is far less sanguine about the removal of the caliphate from the political legitimacy equation, and is far less ready than Ibn Taymiyya to accept the political fragmentation of the Middle Period (c. 1000–1500) as a permanent feature of the Islamic world. Al-Taftazani's views on the caliphate were referred to frequently by proponents of the revival of the caliphate in the late nineteenth and early twentieth centuries. His Sharh was used as a textbook at al-Azhar, and both his Maturidi rationalism and his frequent references to the salaf al-salih ("upright predecessors") appealed to the reformist Salafi movement of the nineteenth century that touted original Islam as the true religion of reason and enlightenment. By contrast, the favoritism toward Hanafism and eventual revival of caliphal universalism by the Ottoman sultans banished Ibn Taymiyya's Hanbali puritanism to the margins, where it became associated with groups on the religious fringe, such as the Wahhabis. However, after the failure of the caliphal revival efforts of the 1920s, Ibn Taymiyya's tactical retreat to "Islamism-in-one-country" got a second look from groups like the Muslim Brotherhood (Ikhwan al-Muslimin) that worked for Islamic renewal from the ground up instead of from the top down.

In the meantime, in addition to eradicating the Baghdad caliphate, the Mongols also brought to the Islamic world a theory of dynastic succession in which God chose the ruler of the world directly, without the agency of the umma, and demonstrated His choice not through the consensus of scholars but through the outcome of military struggles. This made the subject of legitimate political succession less a matter for prescription by men of religion and more a matter for description by historians. The most prominent of these was Ibn Khaldun, "the world's first sociologist," who viewed the succession of political sovereignty as driven by ˓asabiyya—or the ruling dynasty's group cohesion. Indeed, he interprets the restriction by previous theorists of the caliphate to the house of Quraysh not as deriving from hadith text but rather as from the fact that Quraysh was in possession of the ˓asabiyya of the moment during the period of Islamic origins. Although Ibn Khaldun is more of a historian than a religious scholar, his views on the relationship of religion to political succession were often quoted by later ulema because of his general prestige. In particular, his portrayal of the Quraysh lineage requirement as a practical rather than doctrinal consideration was much cited by proponents of non-Quraysh candidates for the caliphate.

Dynastic succession displaced caliphal legitimacy as a political principle in the Islamic world from the Mongols through the period of the early modern Timurid, Safavid, and Ottoman empires. Toward the end of the nineteenth century the Ottoman sultan ˓Abd al-Hamid II tried to counter national separatism among Muslim ethnic minorities in the empire by pushing the idea that the Ottoman sultans were legitimate successors to the caliphate on the basis of a dubious claim that the last descendant of the Abbasid caliphs in Mamluk Cairo had transferred the caliphate to Selim III upon his conquest of Egypt in 1517. Immediately following the defeat of the Ottoman Empire in 1918, several efforts to revive the caliphate as a governing body of the world Muslim community garnered support among Islamic liberals and pan-Islamists. By then it was too late, however, European hegemony having imposed on the Middle East principles of political succession that had neither religious roots nor cultural resonance in the Islamic world. By the end of the twentieth century this had provoked an Islamist reaction whose vision of political legitimacy has far more in common with historically marginal fringe Islamic political movements than with traditional mainstream views of caliphal succession.

See alsoAbu Bakr ; Caliphate ; Empires: Abbasid ; Empires: Umayyad ; Islam and Other Religions ; Tasawwuf ; ˓Umar .

BIBLIOGRAPHY

Barthold, V. V. "Caliph and Sultan." Islamic Quarterly 7 (1963): 117–138.

Binder, Leonard. "al-Ghazali's Theory of Islamic Government." The Muslim World 45 (1955): 229–241.

Crone, Patricia, and Hinds, Martin. God's Caliph: Religious Authority in the First Five Centuries of Islam. Cambridge, U.K.: Cambridge University Press, 1986.

Gibb, H. A. R. "al-Mawardi's Theory of the Khilafah." Islamic Culture 11 (1937): 291–302.

Goitein, S. D. "A Turning Point in the History of the Muslim State." In his Studies in Islamic History and Institutions. Leiden: E. J. Brill, 1968.

Ibn Khaldun. al-Muqaddima. Beirut: Dar al-Kitab al-Lubnani, 1961.

Ibn al-Muqaffa˓, ˓Abdallah. al-Risala fi al-Sahaba. In Conseilleur du Calife. Edited and translated by Charles Pellat. Paris: G. P. Maisonneuve, 1972.

Lambton, A. K. S. State and Government in Medieval Islam: An Introduction to the Study of Islamic Political Theory. London: Oxford University Press, 1981.

Margoliouth, D. S. "The Sense of the Title Khalifah." Oriental Studies Presented to Edward G. Brown. Edited by T. W. Arnold and R. A. Nicholson. Cambridge, U.K.: Cambridge University Press, 1922.

Qadi, Wadad al-. "The Term 'Khalifa' in Early Exegetical Literature." Die Welt des Islams 28 (1988): 392–411.

Qadi, Wadad al-. "Religious Foundation of Late Umayyad Ideology and Practice." In Religious Knowledge and Political Power. Edited by Manuela Martin et al. Madrid: Consejo Superior de Investigaciones Cientificas, 1993.

Watt, W. Montgomery. God's Caliph: Qur˒anic Interpretations and Umayyad Claims. Edinburgh: Edinburgh University Press, 1971.

Mark Wegner

Succession

Disturbance, stress, and succession

Primary succession

Secondary succession

Mechanisms of succession

Climax—the end point of succession

Resources

Succession is a fundamental process of ecological change (which is why it is sometimes called ecological succession), involving the progressive replacement of earlier biotic communities with others over time. The concept of succession was first scientifically considered in the nineteenth century. American plant ecolo-gist Frederic Edward Clements (1874−1945) and American botanist and ecologist Henry Chandler Cowles (1869−1939) are recognized as early developers of theories on succession. In fact, the research on Indiana Dunes of Lake Michigan (United States) were instrumental in the early studies of Cowles on succession.

Succession usually begins with the disturbance of a pre-existing ecosystem, followed by recovery. In the absence of further stand-level disturbance, succession culminates in a stable climax community, the nature of which is determined by climate, soil, and the nature of the local biota. Primary succession occurs on bare substrates that have not been previously modified by biological processes. Secondary succession occurs on substrates that have been modified biologically, and it follows disturbances that have not been so intense as to eliminate the regenerative capacity of the vegetation.

Disturbance, stress, and succession

Disturbance is an episodic stress that causes substantial changes in the structure and function of ecosystems. Depending on its severity and extent, disturbance can influence individual organisms or entire stands, disrupting relationships among individuals within the community, and affecting ecological processes such as productivity, nutrient cycling, and decomposition.

Natural disturbances can be caused by intense events of physical disruption associated with, for example, a hurricane, tornado, oceanic tidal wave, earthquake, the blast of a volcanic eruption, or over geological time spans, the advance and retreat of glaciers. Natural disturbances are also associated with wildfire, and with biological events, such as an irruption of defoliating insects that can kill a mature forest. Human activities are also important sources of ecological disturbances, as is the case of agricultural practices such as plowing, the harvesting of trees from forests, construction activities, and explosions associated with military activities. There are numerous other examples of disturbances caused by human activities.

Note that all of these disturbances can operate at various spatial scales. In some cases, they can result in extensive disturbances over very large areas, for example, when a very severe wildfire consumes millions of hectares of forest. In other cases a disturbance may not cause a stand-level mortality, as when a lightning strike kills a single mature tree in a forest, creating a gap in the overstory, and initiating a microsuccession that culminates in occupation of the gap by another mature tree. Scale is a very important aspect of succession.

Once the intense physical, chemical, or biological stress associated with an event of disturbance is relaxed, succession begins, and this process may eventually restore an ecosystem similar to that present prior to the disturbance. However, depending on environmental circumstances, a rather different ecosystem may develop through post-disturbance succession. For example, if climate change has resulted in conditions that are no longer suitable for the establishment and growth of the same species of trees that dominated a particular stand of old-growth forest prior to its disturbance by a wildfire, then succession will result in the development of a forest of a different character.

Succession can also follow the alleviation of a condition of longer-term, chronic environmental stress. For example, if a local source of pollution by poisonous chemicals is cleaned up, succession will occur in response to the decreased exposure to toxic chemicals. This might occur, for example, if emissions of toxic sulfur dioxide and metals from a smelter are reduced or stopped. This abatement of longer-term environmental stress allows pollution-sensitive species to invade the vicinity of the source, so that succession could proceed. Similarly, removal of some or all of a population of cattle that are chronically overgrazing a pasture would allow the plant community to develop to a more advanced successional stage, characterized by greater biomass and possibly more biodiversity.

Succession can also be viewed as a process of much longer-term ecological change occurring, for example, as a lakebasin gradually in-fills with sediment and organic debris, eventually developing into a terrestrial habitat such as a forest. This particular succession, which occurs through the development and replacement of a long series of community types, can take thousands of years to achieve its progression through the aquatic to terrestrial stages. The series of ecological changes is still, however, properly viewed as a successional sequence (or sere).

Primary succession

Primary successions occur after disturbances that have been intense enough to obliterate any living organisms from the site, and even to have wiped out all traces of previous biological influences, such as soil development. Natural disturbances of this intensity are associated with glaciations, lava flows, and very severe wildfires, while human-caused examples might include the abandonment of a paved parking lot, or an above-ground explosion of a nuclear weapon. In all of these cases, organisms must successfully invade the disturbed site for succession to begin.

A well-known study of primary succession after deglaciation has been conducted in Alaska. This research examined a time series of substrates and plant communities of known age (this is called a chronosequence) at various places along a fiord called Glacier Bay. In this study, historical positions of the glacial front could be dated by various means, including written records and old photographs. The primary succession begins as the first plants colonize newly deglaciated sites and, in combination with climatic influences, begin to modify the post-glacial substrate. These initial plants include mosses, lichens, herbaceous dicotyledonous species such as the river-beauty (Epilobium latifolium ), and a nitrogen-fixing cushion plant known as mountain avens (Dryas octopetala ). These pioneers are progressively replaced as succession continues, first by short statured species of willow (Salix spp.), then by taller shrubs such as alder (Alnus crispa, another nitrogen-fixing plant), which dominates the community for about 50 years. The alder is progressively replaced by sitka spruce (Picea sitchensis ), which in turn is succeeded by a forest of western hemlock (Tsuga heterophylla ) and mountain hemlock (T. mertensiana ). The primary succession at Glacier Bay culminates in the hemlock forest—this is the climax stage, dominated by species that are most tolerant of stresses associated with competition, in a mature habitat in which access to resources is almost fully allocated among the dominant biota.

The plant succession at Glacier Bay is accompanied by other ecological changes, such as soil development. The mineral substrate that is initially available for plant colonization after the meltback of glacial ice is a fine till, with a slightly alkaline pH of (on average) about 8%, and as much as 10%, carbonate minerals. As this primary substrate is progressively leached by percolating water and modified by developing vegetation, its acidity increases, reaching pH 5 after about 70 years under a spruce forest, and eventually stabilizing at about pH 4.7 under a mature hemlock forest. The acidification is accompanied by large reductions of calcium concentration, from initial values as large as 10%, to less than 1%, because of leaching and uptake by vegetation. Other important soil changes include large accumulations of organic matter and nitrogen, due to biological fixations of atmospheric carbon dioxide (CO₂) and dinitrogen (N₂).

Other studies of primary succession have examined chronosequences on sand dunes of known age. At certain places on the Great Lakes, sandy beach ridges are being slowly uplifted from beneath the lake waters by a ponderous rebounding of the land. The process of uplifting is called isostasy, and it is still occurring in response to meltback of the enormously heavy glaciers that were present only 10,000 years ago. The initial plant colonists of newly exposed dunes that were studied on Lakes Michigan and Huron are short-lived species, such as sea rocket (Cakile edentula ) and beach spurge (Euphorbia polygonifolia ). These ephemeral plants are quickly replaced by a perennial dune-grass community, dominated by several grasses (Ammophila breviligulata and Calamovilfa longifolia ). With time, a tall-grass prairie develops, dominated by other species of tall grasses and by perennial, dicotyledonous herbs. The prairie is invaded by shade-intolerant species of shrubs and trees, which form nuclei of forest. Eventually a climax forest develops, dominated by several species of oaks (Quercus spp.) and tulip-tree (Liriodendron tulipifera ). This series of successional plant communities is accompanied by soil development, with broad characteristics similar to those observed at Glacier Bay (although, of course, the rates of change are different).

Secondary succession

Secondary succession occurs after disturbances that are not intense enough to kill all plants, so that regeneration can occur by re-sprouting and growth of surviving individuals, and by the germination of preexisting seeds to establish new plants. This regeneration by surviving plants and seeds is supplemented by an aggressive invasion of plant seeds from elsewhere. Another characteristic of secondary succession is that the soil still retains much of its former character, including previous biological and climatic influences on its development.

Secondary successions are much more common than primary successions, because disturbances are rarely intense enough to obliterate previous ecological influences. Most natural disturbances, such as wind-storms, wildfires, and insect defoliations, are followed by ecological recovery through secondary succession. The same is true of most disturbances associated with human activities, such as the abandonment of agricultural lands, and the harvesting of forests.

Secondary succession can be illustrated by an example involving natural regeneration after the clear-cutting of a mature, mixed-species forest in northeastern North America. In this case, the original forest was dominated by a mixture of angiosperm and coniferous tree species, plus various plants that are tolerant of the stressful, shaded conditions beneath a closed forest canopy. Some of the plants of the original community survive the disturbance of clear-cutting, and they immediately begin to regenerate. For example, each cut stump of red maple (Acer rubrum ) rapidly issues hundreds of new sprouts, which grow rapidly, and eventually self-thin to only one to three mature stems after about 50 years. Other species regenerate from a long-lived seed bank, buried in the forest floor and stimulated to germinate by the environmental conditions occurring after disturbance of the forest. Pin cherry (Prunus pensylvanica ) and red raspberry (Rubus strigosus ) are especially effective at this type of regeneration, and these species are prominent during the first several decades of the secondary succession. Some of the original species do not survive the clear-cutting in large numbers, and they must re-invade the developing habitat. This is often the case of coniferous trees, such as red spruce (Picea rubens ). Another group of species is not even present in the community prior to its disturbance, but they quickly invade the site to take advantage of the temporary conditions of resource availability and little competition immediately after disturbance. Examples of these so-called ruderal species are woody plants such as alders (in this case, Alnus rugosa ) and white birch (Betula papyrifera ), and a great richness of herbaceous perennial plants, especially species in the aster family (Asteraceae), such as goldenrod (Solidago canadensis ) and aster (Aster umbellatus ), along with various species of grasses, sedges, and other monocotyledonous plants.

This secondary succession of plant communities is accompanied by a succession of animal communities. For example, the mature forest is dominated by various species of warblers, vireos, thrushes, woodpeckers, flycatchers, and others. After clear-cutting, this avian community is replaced by a community made up of other native species of birds, which specialize in utilizing the young habitats that are available after disturbance. Eventually, as the regenerating forest matures, the bird species of mature forest re-invade the stand, and their community re-assembles after about 30 to 40 years has passed.

Mechanisms of succession

As noted previously, succession generally begins after disturbance creates a situation of great resource availability that can be exploited by organisms, but under conditions of little competition. The classical explanation of the ecological mechanism of community change during succession is the so-called facilitation model. This theory suggests that the recently disturbed situation is first exploited by certain pioneer species that are most capable of reaching and establishing on the site. These initial species modify the site, making it more suitable for invasion by other species, for example, by carrying out the earliest stages of soil development. Once established, the later-successional species eliminate the pioneers through competition. This ecological dynamic proceeds through a progression of stages in which earlier species are eliminated by later species, until the climax stage is reached, and there is no longer any net change in the community.

Another proposed mechanism of succession is the tolerance model. This concept suggests that all species in the succession are capable of establishing on a newly disturbed site, although with varying successes in terms of the rapid attainment of a large population size and biomass. In contrast with predictions of the facilitation model, the early occupants of the site do not change environmental conditions in ways that favor the subsequent invasion of later-successional species. Rather, with increasing time, the various species sort themselves out through their differing tolerances of the successionally increasing intensity of biological stresses associated with competition. In the tolerance model, competition-intolerant species are relatively successful early in succession when site conditions are characterized by a free availability of resources. However, these species are eliminated later on because they are not as competitive as later species, which eventually develop a climax community.

A third suggested mechanism of succession is the inhibition model. As with the tolerance model, both early- and later-successional species can establish populations soon after disturbance. However, some early species make the site less suitable for the development of other species. For example, some plants are known to secrete toxic biochemicals into soil (these are called allelochemicals), which inhibit the establishment and growth of other species. Eventually, however, the inhibitory species die, and this creates opportunities that later-successional species can exploit. These gradual changes eventually culminate in development of the climax community.

All three of these models, facilitation, tolerance, and inhibition, can be supported by selected evidence from the many ecological studies that have been made of succession (especially plant succession). Although these models differ significantly in their predictions about the organizing principles of successional dynamics, it appears that none of them are correct all of the time. Facilitation seems to be most appropriate in explaining changes in many primary successions, but less so for secondary successions, when early

KEY TERMS

Canopy closure —A point in succession where the sky is obscured by tree foliage, when viewed upward from the ground surface.

Chronosequence —A successional series of stands or soils of different age, originating from a similar type of disturbance.

Competition —An interaction between organisms of the same or different species associated with their need for a shared resource that is present in a supply that is smaller than the potential, biological demand.

Cyclic succession —A succession that occurs repeatedly on the landscape, as a result of a disturbance that occurs at regular intervals.

Ruderal —Refers to plants that occur on recently disturbed sites, but only until the intensification of competition related stresses associated with succession eliminates them from the community.

Sere —A successional sequence of communities, occurring under a particular circumstance of types of disturbance, vegetation, and site conditions.

Successional trajectory —The likely sequence of plant and animal communities that is predicted to occur on a site at various times after a particular type of disturbance.

post-disturbance site conditions are suitable for the vigorous growth of most species. The relatively vigorous development of ecological communities during secondary succession means that competition rapidly becomes an organizing force in the community, so there is an intensification of interactions by which organisms interfere with and inhibit each other. The tolerance and inhibition models more readily explain aspects of these interactions. Overall, it appears that successions are idiosyncratic—the importance of the several, potential mechanisms of succession varies depending on environmental conditions, the particular species that are interacting, and the influence of haphazard events, such as which species arrived first, and in what numbers.

Climax—the end point of succession

The climax of succession is a relatively stable community that is in equilibrium with environmental conditions. The climax condition is characterized by slow rates of change in an old-growth community, compared with more dynamic, earlier stages of succession. The climax stage is dominated by species that are highly tolerant of the biological stresses associated with competition, because access to resources is almost completely allocated among the dominant organisms of the climax community. However, it is important to understand that the climax community is not static, because of the dynamics of within-community microsuccession, associated, for example, with gaps in a forest canopy caused by the death of individual trees. Moreover, if events of stand-level disturbance occur relatively frequently, the climax or old-growth condition will not be achieved.

See also Climax (ecological); Stress, ecological.

Resources

BOOKS

Mayhew, Peter J. Discovering Evolutionary Ecology: Bringing Together Ecology and Evolution. Oxford, UK, and New York: Oxford University Press, 2006.

Herrel Anthony, Thomas Speck, and Nicolas P. Rowe, eds. Ecology and Biomechanics: A Mechanical Approach to the Ecology of Animals and Plants. Boca Raton, FL: CRC/Taylor & Francis, 2006.

Herrera, Carlos M., and Olle Pellmyr. Plant-animal Interactions: An Evolutionary Approach. Malden, MA: Blackwell Science, 2002.

Smith, Thomas Michael. Elements of Ecology. San Francisco, CA: Benjamin Cummings, 2006.

Stiling, Peter D. Ecology: Theories and Applications. Upper Saddle River, NJ: Prentice Hall, 2002.

Bill Freedman

Succession

Succession is a process of ecological change, involving the progressive replacement of earlier biotic communities with others over time. Succession usually begins with the disturbance of a pre-existing ecosystem , followed by recovery. In the absence of further stand-level disturbance, succession culminates in a stable climax community, the nature of which is determined by climate, soil , and the nature of the local biota. Primary succession occurs on bare substrates that have not been previously modified by biological processes. Secondary succession occurs on substrates that have been modified biologically, and it follows disturbances that have not been so intense as to eliminate the regenerative capacity of the vegetation.

Disturbance, stress, and succession

Disturbance is an episodic stress that causes substantial changes in the structure and function of ecosystems. Depending on its severity and extent, disturbance can influence individual organisms or entire stands, disrupting relationships among individuals within the community, and affecting ecological processes such as productivity, nutrient cycling, and decomposition .

Natural disturbances can be caused by intense events of physical disruption associated with, for example, a hurricane, tornado , oceanic tidal wave, earthquake , the blast of a volcanic eruption, or over geological timespans, the advance and retreat of glaciers . Natural disturbances are also associated with wildfire , and with biological events, such as an irruption of defoliating insects that can kill a mature forest. Human activities are also important sources of ecological disturbances, as is the case of agricultural practices such as plowing, the harvesting of trees from forests , construction activities, and explosions associated with military activities. There are numerous other examples of disturbances caused by human activities.

Note that all of these disturbances can operate at various spatial scales. In some cases, they can result in extensive disturbances over very large areas, for example, when a very severe wildfire consumes millions of hectares of forest. In other cases a disturbance may not cause a stand-level mortality, as when a lightning strike kills a single mature tree in a forest, creating a gap in the overstory, and initiating a microsuccession that culminates in occupation of the gap by another mature tree. Scale is a very important aspect of succession.

Once the intense physical, chemical, or biological stress associated with an event of disturbance is relaxed, succession begins, and this process may eventually restore an ecosystem similar to that present prior to the disturbance. However, depending on environmental circumstances, a rather different ecosystem may develop through post-disturbance succession. For example, if climate change has resulted in conditions that are no longer suitable for the establishment and growth of the same species of trees that dominated a particular stand of old-growth forest prior to its disturbance by a wildfire, then succession will result in the development of a forest of a different character.

Succession can also follow the alleviation of a condition of longer-term, chronic environmental stress. For example, if a local source of pollution by poisonous chemicals is cleaned up, succession will occur in response to the decreased exposure to toxic chemicals. This might occur, for example, if emissions of toxic sulfur dioxide and metals from a smelter are reduced or stopped. This abatement of longer-term environmental stress allows pollution-sensitive species to invade the vicinity of the source, so that succession could proceed. Similarly, removal of some or all of a population of cattle that are chronically overgrazing a pasture would allow the plant community to develop to a more advanced successional stage, characterized by greater biomass and possibly more biodiversity .

Succession can also be viewed as a process of much longer-term ecological change occurring, for example, as a lake basin gradually in-fills with sediment and organic debris, eventually developing into a terrestrial habitat such as a forest. This particular succession, which occurs through the development and replacement of a long series of community types, can take thousands of years to achieve its progression through the aquatic to terrestrial stages. The series of ecological changes is still, however, properly viewed as a successional sequence (or sere).

Primary succession

Primary successions occur after disturbances that have been intense enough to obliterate any living organisms from the site, and even to have wiped out all traces of previous biological influences, such as soil development. Natural disturbances of this intensity are associated with glaciation, lava flows, and very severe wildfires, while human-caused examples might include the abandonment of a paved parking lot, or an above-ground explosion of a nuclear weapon. In all of these cases, organisms must successfully invade the disturbed site for succession to begin.

A well-known study of primary succession after deglaciation has been conducted in Alaska. This research examined a time series of substrates and plant communities of known age (this is called a chronosequence) at various places along a fiord called Glacier Bay. In this study, historical positions of the glacial front could be dated by various means, including written records and old photographs. The primary succession begins as the first plants colonize newly deglaciated sites and, in combination with climatic influences, begin to modify the post-glacial substrate. These initial plants include mosses, lichens , herbaceous dicotyledonous species such as the river-beauty (Epilobium latifolium), and a nitrogen-fixing cushion plant known as mountain avens (Dryas octopetala). These pioneers are progressively replaced as succession continues, first by short statured species of willow (Salix spp.), then by taller shrubs such as alder (Alnus crispa, another nitrogen-fixing plant), which dominates the community for about 50 years. The alder is progressively replaced by sitka spruce (Picea sitchensis), which in turn is succeeded by a forest of western hemlock (Tsuga heterophylla) and mountain hemlock (T. mertensiana). The primary succession at Glacier Bay culminates in the hemlock forest—this is the climax stage, dominated by species that are most tolerant of stresses associated with competition , in a mature habitat in which access to resources is almost fully allocated among the dominant biota.

The plant succession at Glacier Bay is accompanied by other ecological changes, such as soil development. The mineral substrate that is initially available for plant colonization after the meltback of glacial ice is a fine till, with a slightly alkaline pH of about 8, and as much as 7-10% carbonate minerals . As this primary substrate is progressively leached by percolating water and modified by developing vegetation, its acidity increases, reaching pH 5 after about 70 years under a spruce forest, and eventually stabilizing at about pH 4.7 under a mature hemlock forest. The acidification is accompanied by large reductions of calcium concentration , from initial values as large as 10%, to less than 1%, because of leaching and uptake by vegetation. Other important soil changes include large accumulations of organic matter and nitrogen , due to biological fixations of atmospheric carbon dioxide (CO2) and dinitrogen (N2).

Other studies of primary succession have examined chronosequences on sand dunes of known age. At certain places on the Great Lakes, sandy beach ridges are being slowly uplifted from beneath the lakewaters by a ponderous rebounding of the land. The process of uplifting is called isostasy , and it is still occurring in response to meltback of the enormously heavy glaciers that were present only 10,000 years ago. The initial plant colonists of newly exposed dunes that were studied on Lakes Michigan and Huron are short-lived species, such as sea rocket (Cakile edentula) and beach spurge (Euphorbia polygonifolia). These ephemeral plants are quickly replaced by a perennial dunegrass community, dominated by several grasses (Ammophila breviligulata and Calamovilfa longifolia). With time, a tall-grass prairie develops, dominated by other species of tall grasses and by perennial, dicotyledonous herbs. The prairie is invaded by shade-intolerant species of shrubs and trees, which form nuclei of forest. Eventually a climax forest develops, dominated by several species of oaks (Quercus spp.) and tulip-tree (Liriodendron tulipifera). This series of successional plant communities is accompanied by soil development, with broad characteristics similar to those observed at Glacier Bay (although, of course, the rates of change are different).

Secondary succession

Secondary succession occurs after disturbances that are not intense enough to kill all plants, so that regeneration can occur by re-sprouting and growth of surviving individuals, and by the germination of pre-existing seeds to establish new plants. This regeneration by surviving plants and seeds is supplemented by an aggressive invasion of plant seeds from elsewhere. Another characteristic of secondary succession is that the soil still retains much of its former character, including previous biological and climatic influences on its development.

Secondary successions are much more common than primary successions, because disturbances are rarely intense enough to obliterate previous ecological influences. Most natural disturbances, such as windstorms, wildfires, and insect defoliations, are followed by ecological recovery through secondary succession. The same is true of most disturbances associated with human activities, such as the abandonment of agricultural lands, and the harvesting of forests.

Secondary succession can be illustrated by an example involving natural regeneration after the clear-cutting of a mature, mixed-species forest in northeastern North America . In this case, the original forest was dominated by a mixture of angiosperm and coniferous tree species, plus various plants that are tolerant of the stressful, shaded conditions beneath a closed forest canopy. Some of the plants of the original community survive the disturbance of clear-cutting, and they immediately begin to regenerate. For example, each cut stump of red maple (Acer rubrum) rapidly issues hundreds of new sprouts, which grow rapidly, and eventually self-thin to only 1-3 mature stems after about 50 years. Other species regenerate from a long-lived seed bank, buried in the forest floor and stimulated to germinate by the environmental conditions occurring after disturbance of the forest. Pin cherry (Prunus pensylvanica) and red raspberry (Rubus strigosus) are especially effective at this type of regeneration, and these species are prominent during the first several decades of the secondary succession. Some of the original species do not survive the clear-cutting in large numbers, and they must re-invade the developing habitat. This is often the case of coniferous trees, such as red spruce (Picea rubens). Another group of species is not even present in the community prior to its disturbance, but they quickly invade the site to take advantage of the temporary conditions of resource availability and little competition immediately after disturbance. Examples of these socalled ruderal species are woody plants such as alders (in this case, Alnus rugosa) and white birch (Betula papyrifera), and a great richness of herbaceous perennial plants, especially species in the aster family (Asteraceae), such as goldenrod (Solidago canadensis) and aster (Aster umbellatus), along with various species of grasses, sedges , and other monocotyledonous plants.

This secondary succession of plant communities is accompanied by a succession of animal communities. For example, the mature forest is dominated by various species of warblers , vireos , thrushes , woodpeckers , flycatchers, and others. After clear-cutting, this avian community is replaced by a community made up of other native species of birds , which specialize in utilizing the young habitats that are available after disturbance. Eventually, as the regenerating forest matures, the bird species of mature forest re-invade the stand, and their community re-assembles after about 30-40 years has passed.

Mechanisms of succession

As noted previously, succession generally begins after disturbance creates a situation of great resource availability that can be exploited by organisms, but under conditions of little competition. The classical explanation of the ecological mechanism of community change during succession is the so-called facilitation model. This theory suggests that the recently disturbed situation is first exploited by certain pioneer species that are most capable of reaching and establishing on the site. These initial species modify the site, making it more suitable for invasion by other species, for example, by carrying out the earliest stages of soil development. Once established, the later-successional species eliminate the pioneers through competition. This ecological dynamic proceeds through a progression of stages in which earlier species are eliminated by later species, until the climax stage is reached, and there is no longer any net change in the community.

Another proposed mechanism of succession is the tolerance model. This concept suggests that all species in the succession are capable of establishing on a newly disturbed site, although with varying successes in terms of the rapid attainment of a large population size and biomass. In contrast with predictions of the facilitation model, the early occupants of the site do not change environmental conditions in ways that favor the subsequent invasion of later-successional species. Rather, with increasing time, the various species sort themselves out through their differing tolerances of the successionally increasing intensity of biological stresses associated with competition. In the tolerance model, competition-intolerant species are relatively successful early in succession when site conditions are characterized by a free availability of resources. However, these species are eliminated later on because they are not as competitive as later species, which eventually develop a climax community.

A third suggested mechanism of succession is the inhibition model. As with the tolerance model, both earlyand later-successional species can establish populations soon after disturbance. However, some early species make the site less suitable for the development of other species. For example, some plants are known to secrete toxic biochemicals into soil (these are called allelochemicals), which inhibit the establishment and growth of other species. Eventually, however, the inhibitory species die, and this creates opportunities that later-successional species can exploit. These gradual changes eventually culminate in development of the climax community.

All three of these models, facilitation, tolerance, and inhibition, can be supported by selected evidence from the many ecological studies that have been made of succession (especially plant succession). Although these models differ significantly in their predictions about the organizing principles of successional dynamics, it appears that none of them are correct all of the time. Facilitation seems to be most appropriate in explaining changes in many primary successions, but less so for secondary successions, when early post-disturbance site conditions are suitable for the vigorous growth of most species. The relatively vigorous development of ecological communities during secondary succession means that competition rapidly becomes an organizing force in the community, so there is an intensification of interactions by which organisms interfere with and inhibit each other. Aspects of these interactions are more readily explained by the tolerance and inhibition models. Overall, it appears that successions are idiosyncratic—the importance of the several, potential mechanisms of succession varies depending on environmental conditions, the particular species that are interacting, and the influence of haphazard events, such as which species arrived first, and in what numbers.

Climax—the end point of succession

The climax of succession is a relatively stable community that is in equilibrium with environmental conditions. The climax condition is characterized by slow rates of change in an old-growth community, compared with more dynamic, earlier stages of succession. The climax stage is dominated by species that are highly tolerant of the biological stresses associated with competition, because access to resources is almost completely allocated among the dominant organisms of the climax community. However, it is important to understand that the climax community is not static, because of the dynamics of within-community microsuccession, associated, for example, with gaps in a forest canopy caused by the death of individual trees. Moreover, if events of stand-level disturbance occur relatively frequently, the climax or old-growth condition will not be achieved.

See also Climax (ecological); Stress, ecological.

Resources

books

Begon, M., J. L. Harper, and C. R. Townsend. Ecology. Individuals, Populations and Communities. 2nd ed. London: Blackwell Sci. Pub., 1990.

Freedman, B. Environmental Ecology. 2nd ed. San Diego: Academic Press, 1995.

Bill Freedman

KEY TERMS

Canopy closure

—A point in succession where the sky is obscured by tree foliage, when viewed upward from the ground surface.

Chronosequence

—A successional series of stands or soils of different age, originating from a similar type of disturbance.

Competition

—An interaction between organisms of the same or different species associated with their need for a shared resource that is present in a supply that is smaller than the potential, biological demand.

Cyclic succession

—A succession that occurs repeatedly on the landscape, as a result of a disturbance that occurs at regular intervals.

Ruderal

—Refers to plants that occur on recently disturbed sites, but only until the intensification of competition related stresses associated with succession eliminates them from the community.

Sere

—A successional sequence of communities, occurring under a particular circumstance of types of disturbance, vegetation, and site conditions.

Successional trajectory

—The likely sequence of plant and animal communities that is predicted to occur on a site at various times after a particular type of disturbance.

Succession

Succession is the gradual transformation or creation of a biological community as new species move into an area and modify local environmental conditions. Primary succession occurs when plant and animal species colonize a previously barren area, such as a new volcanic island, a sand dune, or recently glaciated ground. In these cases every living thing, from soil bacteria and fungi to larger plants and animals, must arrive from some adjacent habitat . Secondary succession is the development of communities in an area that has been disturbed by fire, hurricanes, field clearing, tree felling, or some other process that removes most plants and animals. Intermediate successional communities are known as "seral stages" or "seres."

As early successional species become established, they alter their environment and make it more habitable for later seral stages. Usually a disturbed or barren area has low soil nutrient levels, intense sunlight, and no protection from violent weather. Because precipitation quickly runs off the bare ground, little moisture is available for plant growth. Species that can survive under such harsh conditions have little competition , and they spread quickly. As they grow and thicken, these plants add organic matter to the soil, which aids moisture retention and helps soil bacteria to grow. As soil nutrients and moisture increase, larger shrubs and perennial plants can take root. The shade of these larger species weakens and eventually eliminates the original pioneering species, but it cools the local environment, further improving moisture availability and allowing species that demand relative environmental stability , such as woodland species, to begin moving in. Eventually, shade-tolerant species of plants will come to dominate the area that sun-loving plants had first colonized.

One of the most well-documented examples of primary succession occurred in 1883 when the volcano on the Indonesian island of Krakatoa erupted, destroying most of the island and its life forms, and leaving a new island of bare volcanic rock and ash. Within a few years several species of grasses, ferns, and flowering shrubs had managed to arrive, carried by wind, water, or passing birds from islands 25 mi (40 km) or more distant. Just 40 years later, more than 300 plant species were growing, and in some areas over 12 in (30 cm) of soil had developed: soil bacteria, insects, and decomposers had managed to reach the island and were turning fallen organic detritus into soil. Over the decades, the total number of species gradually stabilized, but the character of the community continued to change as incoming species replaced earlier arrivals. On Krakatoa succession happened with unusual speed because the climate is warm and humid and because the fresh volcanic ash made a nutrient-rich soil.

Early successional species, those most able to quickly establish a foothold, are known as pioneer species. Usually pioneer species are opportunists, able to find nourishment and survive under a great variety of conditions, quick to grow, and able to produce a great number of seeds or offspring at once. Pioneer species have very effective means of dispersing seeds or young, and their seeds can often remain dormant in soil for some time, sprouting only after conditions become suitable. Dandelions are well-known pioneers because they can quickly produce a seed head with hundreds of seeds. Each tiny seed has a lightweight structure that allows the wind to carry it long distances. Dandelions are quick to invade a lawn because of this effective seed-dispersal tactic, because they can survive under sunny or shady conditions, and because they grow and reproduce quickly. In open sunshine, they are competitive enough to establish themselves despite the presence of a thick mat of turf grass.

Later successional species tend to be more shade tolerant, slower to grow and reproduce, and longer lived than pioneer species. Their larger seeds do not disperse as easily (compare the size of an acorn or walnut with that of a dandelion seed), and their seeds cannot remain dormant for very long before they lose viability. Seedlings of some late successional species, such as the Pacific Northwest hemlock, require shade to survive, and most require considerable moisture and soil nutrients.

We usually think of succession occurring after a catastrophic environmental disturbance, but in some cases the gradual environmental changes of succession proceed in the absence of disturbance. Two outstanding examples of this are bog succession and the invasion of prairies by shrubs and trees.

In cool, moist, temperate climates, plant succession often turns ponds into forest through bog succession. Water-loving plants, mainly rush-like sedges and sphagnum moss, gradually creep out from the pond's edges. Often these plants form a floating mat of living and dead vegetation. Other plants—cranberries, Labrador tea, bog rosemary—become established on top of the mat. Organic detritus accumulates below the mat. Eventually the bog becomes firm enough to support black spruce, tamarack, and other tree species. As it fills in and dries, the former pond slowly becomes indistinguishable from the surrounding forest.

Many grasslands persist only in the presence of occasional wildfires. During wet decades or when human activity prevents fires, woody species tend to creep in from the edges of a prairie . If sufficient moisture is available and if fires do not return, open grassland can give way to forest. Fire suppression has aided the advance of forests in this way across much of the United States, Canada, and Mexico. Grazing or browsing animals can also be important forces in maintaining biological communities. Adding or removing grazers can initiate successional processes.

Longer, slower disturbances than fire or field clearing can also initiate succession. Over the course of centuries, climate change can cause significant alteration in the character of biomes. Minor variations in rainfall or temperature ranges can alter community structure for decades or centuries. The end of the last glacial period about 10,000 years ago allowed tundra , then grasslands, then temperate forests to advance northward across North America. Even geologic activity, such as mountain building or changes in sea level, has caused succession. More recently, human introductions of species from one continent to another have caused significant restructuring of some biological communities.

Turnover from one community to another may occur in just a few years or decades, as it did on Krakatoa. Stages in bog succession may take a hundred years or more. Often, succession continues for centuries or millennia before a stable and relatively constant biological community emerges. This is especially likely in areas whose climate is moist and mild enough to support the high species diversity of temperate or tropical rain forests . However, simpler ecosystems such as arctic tundra may take centuries to recover from disturbance because low temperatures and short summers make growth rates almost universally slow.

Generally, successional processes are understood to lead ultimately to the emergence of a climax community, a group of species perfectly suited to a region's climate, soil types, and other environmental conditions. Climax communities are said to exist in equilibrium in their environments; where early successional species groups tend to facilitate the development of later stages, climax communities, sometimes called mature communities, tend to have self-perpetuating characteristics or mechanisms that help maintain local environmental conditions and help the community to persist. In the 1930s, F. E. Clements, one of the best-known plant ecologists in the United States, identified a list of just 14 climax communities that he claimed were the final result of succession for all the various sets of environmental conditions in the country.

More recent evaluations of climax communities, however, have concluded that climax forests are often a patchwork of stable and unstable areas. In an old-growth forest in the Pacific Northwest, hemlock and spruce may compose the local climax community, but every time a large tree falls, it creates a sunny opening that makes way for other seral species to grow for a time. Occasional fires disturb larger patches of forest, and succession starts again from the beginning in disturbed areas. The entire biome is more a shifting and changing mosaic than a uniform and unchanging forest. Often, slight gradations in soil types, slope, exposure, and moisture cause a variety of stable communities to blend in an area. The term "polyclimax community" was developed to recognize the complexity of such assemblages.

In some cases, climax communities may be difficult to distinguish at all. For instance, in a biome regularly disturbed by fire, "climax" species usually require fire to aid seed germination and eliminate competitors. Definitions here become somewhat blurred: Is a climax community one that exists without disturbance? Is fire a disturbance or a maintenance factor? Even if a very old forest community is considered, on a time scale of thousands of years, it may be difficult to determine whether what is observed today is really a permanent climax community or just a very longstanding seral stage. Despite these questions, the concept of an ultimate climax community is central to the idea of succession.

Usually climax communities are considered more diverse than intermediate communities. Because climax communities can remain stable for a long time, species can diversify and develop specialized niches. This specialization can lead to the coexistence of a great number of species, as is the case in tropical rain forests, where thousands of species may share just a few acres of forest. In some cases, however, intermediate seral stages actually have greater diversity because they contain elements of multiple communities at once.

[Linda Rehkopf ]

RESOURCES

BOOKS

Brown, J. H., and A. C. Gibson. Biogeography. St. Louis: Mosby, 1983.

Ricklefs, R. E. Ecology. 3rd ed. New York: W. H. Freeman and Co., 1990.