Productivity and species richness in an arid ecosystem: a long-term perspective
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There is little consensus on the form of the relationship between biodiversity and productivity, and most of the research examining it has been done in temperate grasslands, with arid ecosystems receiving comparatively little attention. Using 9 years of data collected using standardized sampling methods from five different community types in the Chihuahuan Desert (Jornada Basin Long-Term Ecological Research site, New Mexico, USA), we evaluate the relationship between productivity and species richness at multiple spatial scales. The relationship was consistently unimodal at the largest scale considered; however, community types differed in both the form of the relationship and the degree to which patterns fluctuated over time. Although significant linear and unimodal patterns were evident, these models fit poorly, suggesting that annual primary productivity is a weak predictor of mean species richness in arid communities. We suggest that productivity–diversity relationships are best described by a boundary that places an upper limit on species coexistence across the gradient of productivity for a site. This upper limit often appears to be maximized at intermediate levels of productivity, but it has relatively few points on the downward portion of the boundary. By focusing efforts on characterizing boundaries, approaches should be developed to determine the factors that are reducing species richness compared to what would be expected, given the level of productivity.
KeywordsArid ecosystem Productivity Quantile regression Species richness Unimodal
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A portion of this work was conducted during a distributed seminar course at Texas Tech University entitled “Using a Knowledge Network to Explore Scale-Dependent Relationships Between Species Richness and Productivity” and was supported by NSF Grant # DEB-99-80154 and the National Center for Ecological Analysis and Synthesis, a center funded by NSF (Grant #DEB-94-21535), the University of California at Santa Barbara, and the State of California. Additional support was provided by the Department of Biological Sciences, Texas Tech University. Data were provided by the Jornada Long-Term Ecological Research (LTER) projects, and funding for these data was provided by NSF (Grants DEB-92-40261 and DEB 94-11971). S.M. Ernest, S. Andelman, S.␣Scheiner, E. Seabloom, E. Sobek, M. Smith, A. Sparrow, R. Waide, J. Williams, M., E. Sobek, Willig, and an anonymous reviewer provided insightful and constructive comments.
- Cade B.S. and Noon B.R. (2003). A gentle introduction to quantile regression for ecologists. Frontiers in Ecology 1:412–420Google Scholar
- Chapin F.S., III, Osvaldo E.S., Burke I.C., Grime J.P., Hooper D.U., Lauenroth W.K., Lombard A., Mooney H.A., Mosier A.R., Naeem S., Pacala S.W., Roy J., Steffen W.L. and Tilman D. (1998). Ecosystem consequences of changing biodiversity: experimental evidence and a research agenda for the future. BioScience 48:45–52CrossRefGoogle Scholar
- Conley W., Conley M.R. and Karl T.R. (1992). A computational study of episodic events and historical context in long-term ecological processes: climate and grazing in the northern Chihuahuan Desert. Coenoses 7:1–19Google Scholar
- Crawley M.J. (2005). Statistics: An Introduction Using R. John Wiley and Sons, EnglandGoogle Scholar
- Gotelli N.J. and Entsminger G.L. 2001. EcoSim: Null Models Software for Ecology. Version 7.0. Acquired Intelligence Inc. and Kesey-Bear. URL http://www.homepages.together.net/∼ ∼gentsmin/ecosim.htm.
- Grime J.P. 1979. Plant Strategies and Vegetation Processes. John Wiley and SonsGoogle Scholar
- Guo Q. and Berry W.L. (1998). Species richness and biomass: dissection of the hump-shaped relationships. Ecology 79:2555–2559Google Scholar
- Huston M.A. 1994. Biological Diversity: The Coexistence of Species in Changing Landscapes. Cambridge University PressGoogle Scholar
- Huston M.A. (2002). Introductory essay: critical issues for improving predictions. In: Scott J.M., Heglund P.J., Morrison M.L., Haufler J.B., Raphael M.G., Wall W.A., and Samson F.B. (eds). Predicting Species Occurrences: Issues of Accuracy and Scale. Island Press, Washington, pp. 7–21Google Scholar
- Koenker R. 2005. The Quantreg Package Ver. 3.82. Retrieved from http://www.econ.uiuc.edu/∼ ∼roger/research/rq/rq.html
- Mittelbach G.G., Steiner C.F., Scheiner S.M., Gross K.L., Reynolds H.L., Waide R.B., Willig M.R., Dodson S.I. and Gough L. (2001). What is the observed relationship between species richness and productivity?. Ecology 82:2381–2396Google Scholar
- R Development Core Team. 2005. A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. URL http://www.R- project.org.
- Reynolds J.F., Virginia R.A., Kemp P.R., de Soyza A.G. and Tremmel D.C. (1999). Impact of drought on desert shrubs: Effects of seasonality and degree of resource island development. Ecol. Monogr. 69:69–106Google Scholar
- Rosenzweig M.L., and Abramsky Z. (1993). How are diversity and productivity related?. In: Ricklefs R.E. and Schluter D. (eds). Species Diversity in Ecological Communities: Historical and Geographical Perspectives. University of Chicago Press, Chicago, pp. 52–65Google Scholar
- Rosenzweig M.L. 1995. Species Diversity in Space and Time. Cambridge University PressGoogle Scholar
- Scharf F.S., Juanes F. and Sutherland M. (1998). Inferring ecological relationships from the edges of scatter diagrams: comparison of regression techniques. Ecology 79:448–460Google Scholar
- Scheiner S.M., Cox S.B., Willig M.R., Mittelbach G.G., Osenberg C. and Kaspari M. (2000). Species richness, species-area curves and Simpson’s paradox. Evolut. Ecol. Res. 2:791–802Google Scholar
- Tilman D. (1999). The ecological consequences of changes in biodiversity: a search for general principles. Ecology 80:1455–1474Google Scholar
- Tilman D. and Pacala S. 1993. The maintenance of species richness in plant communities. In: Ricklefs R.E. and Schluter, D. Species Diversity in Ecological Communities: Historical and Geographical Perspectives. University of Chicago Press, pp. 13–25Google Scholar
- Vasander H. (1987). Diversity of understorey biomass in virgin and in drained and fertilized southern boreal mires in eastern Fennoskandia. Ann. Bot. Fenn. 24:137–153Google Scholar
- Venables W.N. and Ripley B.D. (2002). Modern Applied Statistics with S. Springer-Verlag, New YorkGoogle Scholar