Temporal Patterns in Rates of Community Change during Succession

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<ul><li><p>The University of Chicago</p><p>Temporal Patterns in Rates of Community Change during Succession.Author(s): KristinaJ.AndersonSource: The American Naturalist, Vol. 169, No. 6 (June 2007), pp. 780-793Published by: The University of Chicago Press for The American Society of NaturalistsStable URL: http://www.jstor.org/stable/10.1086/516653 .Accessed: 13/05/2013 02:31</p><p>Your use of the JSTOR archive indicates your acceptance of the Terms &amp; Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp</p><p> .</p><p>JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.</p><p> .</p><p>The University of Chicago Press, The American Society of Naturalists, The University of Chicago arecollaborating with JSTOR to digitize, preserve and extend access to The American Naturalist.</p><p>http://www.jstor.org </p><p>This content downloaded from on Mon, 13 May 2013 02:31:46 AMAll use subject to JSTOR Terms and Conditions</p></li><li><p>vol. 169, no. 6 the american naturalist june 2007 </p><p>Temporal Patterns in Rates of Community</p><p>Change during Succession</p><p>Kristina J. Anderson*</p><p>Biology Department, University of New Mexico, Albuquerque,New Mexico 87131</p><p>Submitted May 22, 2006; Accepted December 13, 2006;Electronically published April 6, 2007</p><p>Online enhancements: appendix, data files.</p><p>abstract: While ecological dogma holds that rates of communitychange decrease over the course of succession, this idea has yet tobe tested systematically across a wide variety of successional se-quences. Here, I review and define several measures of communitychange rates for species presence-absence data and test for temporalpatterns therein using data acquired from 16 studies comprising 62successional sequences. Community types include plant secondaryand primary succession as well as succession of arthropods on de-faunated mangrove islands and carcasses. Rates of species gain gen-erally decline through time, whereas rates of species loss display nosystematic temporal trends. As a result, percent community turnovergenerally declines while species richness increasesboth in a decel-erating manner. Although communities with relatively minor abioticand dispersal limitations (e.g., plant secondary successional com-munities) exhibit rapidly declining rates of change, limitations arisingfrom harsh abiotic conditions or spatial isolation of the communityappear to substantially alter temporal patterns in rates of successionalchange.</p><p>Keywords: colonization, extinction, turnover, primary succession,secondary succession, arthropods.</p><p>Successioncommunity development following a distur-bance or formation of a new habitatis traditionallythought to embody increasing community stabilitythrough time (e.g., Odum 1969; Whittaker 1975); that is,rates of community change often decrease through timeduring succession (e.g., Drury and Nisbet 1973; Jassby andGoldman 1974; Bornkamm 1981; Schoenly and Reid 1987;Prach et al. 1993; Myster and Pickett 1994; Foster and</p><p>* E-mail: kristaa@unm.edu.</p><p>Am. Nat. 2007. Vol. 169, pp. 780793. 2007 by The University of Chicago.0003-0147/2007/16906-41849$15.00. All rights reserved.</p><p>Tilman 2000; Sheil et al. 2000). Meanwhile, species rich-ness usually increases initially (e.g., Odum 1969; Swaineand Hall 1983; Saldarriaga et al. 1988; Whittaker et al.1989) but then often declines (e.g., AuClair and Goff 1971;Schoenly and Reid 1987; Lichter 1998). However, a clearsynthesis regarding temporal patterns in rates of com-munity change during succession is currently lacking.Here, I (1) describe measures of species gain and loss ratesand how these combine to determine turnover rates andspecies richness, (2) examine the temporal patterns incommunity change rates during succession across a varietyof community types, and (3) discuss the mechanisms thatmay underlie predominant temporal patterns in speciescolonization rates and richness.</p><p>Species gain (colonization) rate. Gain rate (G; time1) isthe rate at which previously absent species appear in thecommunity. In order to measure the magnitude of gainrelative to the existing community, gain rate may be ex-pressed as a proportion of the average number of speciespresent during the measurement period (Gp):</p><p>GG p . (1)p [ ](1/2) S(t ) S(t )1 2</p><p>Here, S(t1) and S(t2) are species richness at the beginningand end of the sampling interval, respectively. The reap-pearance of previously present species that had disap-peared may be included (G and Gp) or excluded ( and</p><p>G); exclusion assumes that absences are an artifact ofGp</p><p>sampling and/or population stochasticity rather than a bi-ologically meaningful event.</p><p>Several major mechanisms may be expected to influencetemporal patterns in gain rate. First, gain rate will be con-strained by the number of species that can establish them-selves and simultaneously persist in the community (KS).Early in succession, when S is far below KS, G will belimited primarily by dispersal. As S approaches KS and theintensity of competition increases, gain rate will decrease(e.g., MacArthur and Wilson 1963; Tilman 2004) until, atKS, it is approximately balanced by loss rate (Goheen etal. 2005). Although clearly an oversimplification, this</p><p>This content downloaded from on Mon, 13 May 2013 02:31:46 AMAll use subject to JSTOR Terms and Conditions</p></li><li><p>Temporal Patterns in Succession Rate 781</p><p>Figure 1: Schematic diagram showing hypothesized effects of the number of species a community can potentially hold (KS; AC) and dispersalrates (A, D, E) on species richness (S) and gain rate (G). AC, Hypothesized effects of KS being constant (A), sigmoidal (B), or peaked (C) overtime. A, D, E, Consequences of dispersal rates being such that each time step witnesses the arrival of 90% (A), 50% (D), and 10% (E) of thepotential colonists that had not yet arrived. An implicit assumption is that when dispersal limitations do not interfere, S tracks KS.</p><p>schema is useful for making first-order predictions re-garding temporal patterns in succession rate. For example,in the simple case where dispersal is not highly limitingand where KS remains relatively constant over the courseof successionas may generally be the case in secondarysuccessiongain rate should start high and rapidly de-crease as S approaches KS and the intensity of competitionincreases (e.g., MacArthur and Wilson 1963; Bazzaz 1979;Walker and Chapin 1987; Tilman 2004). In the more com-plex case where KS changes substantiallyperhaps as aresult of changing resource availabilitygain rate will takethe form of the derivative of KS(t). Thus, for example, asigmoidal increase in KS over timeas may be the case inharsh environments where time and/or facilitation are re-quired to make resources available (e.g., Walker andChapin 1987)would result in a peaked function of G(fig. 1B), whereas a peak in KSas may be the case forsuccession on ephemeral resources such as corpseswould imply a roughly linear decrease in G (fig. 1C). Inboth cases, the maximum G would be lower than that ofa community that does not face such abiotic limitations(cf. fig. 1A1C). Second, G will be controlled in large partby the rate at which propagules of new species arrive at</p><p>the site. If the rate at which propagules arrive remainsconstant through time, the rate at which new species arrivenecessarily decreases simply because many species are nolonger new. If, at each time step, a constant proportionof the species pool that is not yet represented arrives, G(t)will take an exponential form (fig. 1A, 1D, 1E). Sites thatreceive large numbers of propagules (e.g., 90% of unrep-resented species arrive at each time step) will have rapidlydecreasing G(t) and rapidly plateauing S(t) (fig. 1A). Thelower the rate of propagule arrival, the less rapid the de-crease in G(t), the lower the G(0), and the longer the timeuntil S reaches KS (cf. fig. 1A, 1D, 1E). As a result, suc-cessional communities facing strong dispersal limitationwill display relatively nondescript temporal patterns in G(fig. 1E). Note that, under this scenario, the size of theregional species pool should affect gain rate but not tem-poral patterns therein. Thus, gain rates should decreaseless dramatically in isolated locations (MacArthur and Wil-son 1963; Walker and del Moral 2003) and for commu-nities composed of poorly dispersing species than in suc-cessional communities with high dispersal rates. Third, Gmay be affected by herbivory or predation at any stage ofsuccession (e.g., Walker and Chapin 1987; Fraser and</p><p>This content downloaded from on Mon, 13 May 2013 02:31:46 AMAll use subject to JSTOR Terms and Conditions</p></li><li><p>782 The American Naturalist</p><p>Grime 1999; Howe and Brown 1999; Fagan and Bishop2000). Finally, G(t) may be influenced by loss rate (Barthaet al. 2003), especially in the later phases of successionwhen competition is more intense (e.g., MacArthur andWilson 1963; Bazzaz 1979; Lichter 2000). In combination,these four factors may affect G(t) in a variety of ways.Generally, G will decrease at any time that KS is not in-creasing, and the rate of this decrease will depend on dis-persal rates. An increase in KS will counteract this tendencyfor gain to decrease, sometimes causing it to increase.Conversely, a decrease in KS will force G to be less thanthe loss rate.</p><p>Species loss (extinction) rate. Loss rate (L; time1) is therate at which species disappear from the community. Aswith gain rate, this may be expressed as a proportion ofthe species present over the measurement period (Lp):</p><p>LL p . (2)p [ ](1/2) S(t ) S(t )1 2</p><p>This measure represents the probability that any givenspecies will be lost in one unit of time. Again, species thatdisappear and later reappear may be included (L and Lp)or excluded ( and ), depending on whether such tem- L Lpporary absence is deemed to be biologically significant.</p><p>Several mechanisms may act on temporal trends in lossrate. For example, L should increase with the number ofspecies that may potentially be lost (S). Additionally, bothL and Lp may be expected to increase as the intensity ofcompetition increases (e.g., MacArthur and Wilson 1963;Bazzaz 1979; Lichter 2000). On the other hand, this maybe counteracted by a decreasing rate of invading speciesthat could potentially outcompete existing ones. Addi-tionally, if average body size increases significantly overthe course of succession, increasing life spans may resultin decreasing loss rates (Drury and Nisbet 1973). Thus, itis difficult to predict a priori how L and Lp will changeover successional time. The findings of previous studiesare likewise ambivalent, showing no relationship (Fosterand Tilman 2000), a positive relationship (Facelli et al.1987), or a peaked relationship (Lichter 1998) between Lpand time. Species turnover rate and richness can be ex-pressed straightforwardly as functions of G and L.</p><p>Species turnover rate. Turnover rate (T; time1) is theaverage of gains and losses:</p><p>1 ( )Tp G L . (3)2</p><p>Percent turnover has been defined in a variety of ways(Wilson and Shmida 1984; Koleff et al. 2003); I modify acommon measure of community turnover, Srensens co-</p><p>efficient (CS; Srensen 1948; Koleff et al. 2003), to expressthe rate of percent turnover (Tp):</p><p>C 1 {2S /[S(t ) S(t )]}S C 1 2T p pp t t t t2 1 2 1</p><p>G L Tp p . (4)[ ]S(t ) S(t ) (1/2) S(t ) S(t )1 2 1 2</p><p>Here, SC is the number of species present at both thebeginning and the end of the measurement period. Itshould be noted that, as opposed to narrow-sense mea-sures of turnover that focus on changes in species identity(e.g., Routledge 1977), this measure will also be stronglyinfluenced by changes in species richness (Koleff et al.2003). Note also that Tp is the average of Gp and Lp andrelates to T in the same way that G and L relate to Gp andLp (eqq. [1], [2], [4]). Just as with gain and loss, turnovermay include (T and Tp) or exclude ( and ) species</p><p> T Tpthat disappear temporarily.</p><p>Turnover rate, as the average of gain and loss rates, willbe driven by the mechanisms that drive them. As gaingenerally substantially exceeds loss during early succession,it is likely that T and Tp will decrease with time, if sucha trend exists for gain rate. Such a trend may be accen-tuated in communities where increasing size results inlengthening life cycles (Drury and Nisbet 1973; Foster andTilman 2000). As species richness increases, Tp will alsotend to decrease and possibly to increase toward the endof succession in communities using ephemeral resources(e.g., corpses). These patterns have been previously ob-served in both plant and animal communities (e.g., Born-kamm 1981; Schoenly 1992; Myster and Pickett 1994; Fos-ter and Tilman 2000; Chytry et al. 2001). However, itshould be noted that studies reporting a decrease in turn-over rate based on Shugart and Hetts (1973) l do so inerror (Myster and Pickett 1994; Blatt et al. 2003). Thismeasure is flawed in that (1) while purporting to measureturnover, it actually considers only loss and (2) it is definedas the fraction of original species remaining (ln trans-formed) divided by the age of the community, resultingin a mathematically trivial relationship between rate andtime (i.e., vs. x) that is guaranteed to decrease in ay/xdecelerating manner.</p><p>Species richness. Species richness (S) is defined as thenumber of species present in a community and may ormay not exclude species that are temporarily absent (S and</p><p>, respectively); S(t) is the cumulative difference betweenSgains and losses:</p><p>t t</p><p>Sp G(t) L(t). (5) 0 0</p><p>This content downloaded from on Mon, 13 May 2013 02:31:46 AMAll use subject to JSTOR Terms and Conditions</p></li><li><p>Temporal Patterns in Succession Rate 783</p><p>Thus, elucidation of temporal patterns in G and L willallow description of temporal patterns of S.</p><p>Here, I analyze temporal patterns in rates of species gain(G, Gp, , and ), loss (L, Lp, , and ), and turnover</p><p> G G L Lp p(T, Tp, , and ) over multiple successional sequences</p><p> T Tpin a variety of community types (table 1). Specifically, Iconsider plant secondary succession in worldwide loca-tions; plant primary succession on volcanic substrates, onsand dunes, and following a receding glacier; terrestrialarthropod succession on defaunated mangrove islands;and arthropod succession on corpses. Detailed descrip-tions of these successional seres are given in the appendixin the online edition of the American Naturalist. For eachrate measuresuccessional sequence combination, I con-sider several mathematical forms that may potentially de-scribe the community change rate, Y(t) (i.e., gain, loss, orturnover), as a function of time over the course of suc-cession. First, the null hypothesis is that Y(t) is constant:</p><p>Y(t)p Y . (6)0</p><p>Second, if a rate is driven by a process that changes linearlywith time, it may be described by a linear function:</p><p>Y(...</p></li></ul>


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