Compositional variation in grassland plant communities

• Autores: Bakker, Jonathan D.; Price, Jodi N.; Henning, Jeremiah A.; Batzer, Evan E.; Ohlert, Timothy J.; Wainwright, Claire E.; Adler, Peter B.; Alberti, Juan; Arnillas, Carlos Alberto; Biederman, Lori A.; Peri, Pablo Luis; Wardle, Glenda M.
• Año de publicación: 2023
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Ecosphere 14 (6) : e4542. (June 2023)
• Materia: Grasslands; Composition; Temporal Variations; Vegetation; Praderas; Fertilizer Application; Aplicación de Abonos; Spatial Variations; Variaciones Espaciales; Composición; Variaciones temporales; Vegetación; Plant Community; Sorensen Dissimilarity; Turnover; Bray–Curtis Dissimilarity; NutNet; Comunidad Vegetal; Disimilitud Sorensen; Rotación; Disimilitud Bray -Curtis; Fertilización
• Institución: Instituto Nacional de Tecnología Agropecuaria

Human activities are altering ecological communities around the globe. Understanding the implications of these changes requires that we consider the composition of those communities. However, composition can be summarized by many metrics which in turn are influenced by different ecological processes. For example, incidence-based metrics strongly reflect species gains or losses, while abundance-based metrics are minimally affected by changes in the abundance of small or uncommon species. Furthermore, metrics might be correlated with different predictors. We used a globally distributed experiment to examine variation in species composition within 60 grasslands on six continents. Each site had an identical experimental and sampling design: 24 plots × 4 years. We expressed compositional variation within each site—not across sites—using abundance- and incidence-based metrics of the magnitude of dissimilarity (Bray–Curtis and Sorensen, respectively), abundance- and incidence-based measures of the relative importance of replacement (balanced variation and species turnover, respectively), and species richness at two scales (per plot-year [alpha] and per site [gamma]). Average compositional variation among all plot-years at a site was high and similar to spatial variation among plots in the pretreatment year, but lower among years in untreated plots. For both types of metrics, most variation was due to replacement rather than nestedness. Differences among sites in overall within-site compositional variation were related to several predictors. Environmental heterogeneity (expressed as the CV of total aboveground plant biomass in unfertilized plots of the site) was an important predictor for most metrics. Biomass production was a predictor of species turnover and of alpha diversity but not of other metrics. Continentality (measured as annual temperature range) was a strong predictor of Sorensen dissimilarity. Metrics of compositional variation are moderately correlated: knowing the magnitude of dissimilarity at a site provides little insight into whether the variation is driven by replacement processes. Overall, our understanding of compositional variation at a site is enhanced by considering multiple metrics simultaneously. Monitoring programs that explicitly incorporate these implications, both when designing sampling strategies and analyzing data, will have a stronger ability to understand the compositional variation of systems and to quantify the impacts of human activities.
EEA Santa Cruz
Fil: Bakker, Jonathan D. University of Washington. School of Environmental and Forest Sciences; Estados Unidos
Fil: Price, Jodi N. Charles Sturt University. Gulbali Institute; Australia.
Fil: Henning, Jeremiah A. University of Minnesota. Department of Ecology, Evolution, and Behavior; Estados Unidos
Fil: Henning, Jeremiah A. University of South Alabama. Department of Biology; Estados Unidos
Fil: Batzer, Evan E. University of California at Davis. Department of Plant Sciences; Estados Unidos
Fil: Ohlert, Timothy J. University of New Mexico. Department of Biology; Estados Unidos
Fil: Wainwright, Claire E. University of Washington. School of Environmental and Forest Sciences; Estados Unidos
Fil: Adler, Peter B. Utah State University. Department of Wildland Resources and the Ecology Center; Estados Unidos
Fil: Alberti, Juan. Universidad Nacional de Mar del Plata. Instituto de Investigaciones Marinas y Costeras (IIMyC). Laboratorio de Ecología; Argentina.
Fil: Alberti, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.
Fil: Arnillas, Carlos Alberto. University of Toronto – Scarborough. Department of Physical and Environmental Sciences. Scarborough; Canadá.
Fil: Biederman, Lori A. Iowa State University. Department of Ecology, Evolution, and Organismal Biology; Estados Unidos
Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.
Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.
Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral (UNPA); Argentina.
Fil: Wardle, Glenda M. University of Sydney. School of Life and Environmental Sciences. Desert Ecology Research Group; Australia