Spatial constraints masking community assembly rules: A simulation study
- 35 Downloads
The effect of competition on species coexistence is usually strongly modified by other factors especially in non-equilibrium systems of sessile organisms with limited availability of propagules. As a consequence, competition-based assembly rules (even if their existence seems to be unambiguously detected) would result in incomplete understanding of the coexistence of species in plant communities. J. Bastow Wilson suggested measuring variance deficit in the number of co-occurring species as a means to detect niche limitation in a community. The method provides a relatively simple and quick “snap-shot” analysis of a community. However, it has been questioned whether niche limitation is the only factor which might account for variance deficit.
The paper presents a spatially explicit simulation experiment in which artificial communities are produced by pre-defined rules for competitive interactions. Then we examine whether these rules can be detected by a proposed method for pattern analysis. Two limiting cases are simulated: (A) all the species share the same niche, and (B) all the species have different niches. The difference between these cases in the variance of species numbers is examined. Using the simulation results, some basic spatial constraints upon species assembly are emphasized.
It is argued that the assumptions of Wilson’s approach confine its applicability to species-saturated equilibrium communities. The study of assembly rules in dynamically changing, spatially structured communities requires the consideration of a set of coenological characteristics and the use of careful spatio-temporal scaling to detect their patterns. The use of spatially explicit individual-based models to study the mechanisms and constraints limiting species coexistence at different scales is suggested.
KeywordsCompetition Niche limitation Pattern analysis Spatially explicit population dynamics Space series Species richness
Unable to display preview. Download preview PDF.
- Bartha S. (1992a): Gyomnövényközösségek szünmorfogenezise külszíni szénbányák meddőhányóin. (Vegetation development on dumps from strip-coal mining).—Ph.D. thesis, Vácrátót.Google Scholar
- Bartha S. (1992b): Preliminary scaling for multi-species coalitions in primary succession.—Abstr. Bot. (Budapest) 16: 31–41.Google Scholar
- Bartha S. &Horváth F. (1987): Application of long transects and information theoretical functions to pattern detection I. Transects versus isodiametric sampling units.—Abstr. Bot. (Budapest) 11: 9–26.Google Scholar
- Bycroft C.M., Nicolaou N., Smith B. &Wilson J.B. (1993). Community structure (niche limitation and guild proportionality) in relation to the effect of spatial scale, in aNothofagus forest sampled with a circular transect.—New Zealand J. Ecol. 17: 95–101.Google Scholar
- Czárán T. (1993): PATPRO: A Monte-Carlo simulation program for multispecies neighborhood competition. —Abstr. Bot. (Budapest) 17: 275–281.Google Scholar
- Diamond J.M. (1975): Assembly of species communities.—In:Cody M.L. &Diamond J.M. [eds.]: Ecology and evolution of communities, Harvard University Press, Cambridge, pp. 342–444.Google Scholar
- Greig-Smith P. (1983): Quantitative plant ecology. Ed. 3.—University of California Press, Berkeley.Google Scholar
- Hogeweg P., Hesper B., van Schaik C.P. &Beeftink W.G. (1985): Patterns in vegetation succession, an ecomorphological study.—In:White J. [ed.]: The population structure of vegetation, Dr. W. Junk Publ., Dordrecht, pp. 637–666.Google Scholar
- Journel A.G. &Huijbregts C. (1978): Mining geostatistics.—Academic Press, London.Google Scholar
- Juhász-Nagy P. (1984): Spatial dependence of plant populations. Part 2. A family of new models.—Acta Bot. Acad. Sci. Hung. 30: 363–402.Google Scholar
- Kolasa J. &Pickett S.T.A. [eds.] (1991): Ecological heterogeneity.—Springer-Verlag, New York.Google Scholar
- Lepš J. (1990): Can underlying mechanisms be deduced from observed patterns?—In:Krahulec F., Willems J., Agnew A.D.Q. &Agnew S. [eds.]: Spatial processes in plant communities, Academia, Praha, pp. 1–13.Google Scholar
- Lepš J. (1995): Variance deficit is not reliable evidence for niche limitation.—Folia Geobot. Phytotax. 30: 455–459.Google Scholar
- Palmer M.W. (1987): Variability in species richness within Minnesota oldfields: a use of the variance test.— Vegetatio 70: 61–64.Google Scholar
- Pickett S.T.A. &White P.S. [eds.] (1985): The ecology of natural disturbance and patch dynamics.— Academic Press, New York.Google Scholar
- Podani J., Czárán T. &Bartha S. (1993): Pattern, area and diversity: the importance of spatial scale in species assemblages.—Abstr. Bot. (Budapest) 17: 37–51.Google Scholar
- Shmida A. &Ellner S. (1984): Coexistence of plant species with similar niches.—Vegetatio 58: 29–55.Google Scholar
- Tilman D. &Pacala S. (1993): The maintenance of species richness in plant communities.—In:Ricklefs R.E. &Schluter D. [eds.]: Species diversity in ecological communities, University of Chicago Press, Chicago, pp. 13–25.Google Scholar
- Tóthmérész B. (1994): Statistical analysis of spatial pattern in plant communities.—Coenoses (Trieste) 9: 33–41.Google Scholar
- Tóthmérész B. &Erdei Zs. (1992): The effect of species dominance on information theory characteristics of plant communities.—Abstr. Bot. (Budapest) 16: 43–47.Google Scholar
- Wilson J.B. (1989): A null model of guild proportionality, applied to stratification of a New Zealand temperate rain forest.—Oecologia (Berlin) 80: 263–267.Google Scholar