Bellemare, Jesse , Geber, Monica .
Species richness and plant community phylogenetic structure are correlated with a key environmental gradient in Temperate Deciduous Forests of the northeastern U.S.
Ecological theories typically predict that species richness in communities should represent the outcome of contemporary environmental conditions and local ecological interactions operating over limited spatial and temporal scales. However, evidence is increasing that local diversity patterns may also be influenced by longer-term, larger-scale biogeographical and evolutionary processes. In this study we investigated plant communities along a prominent species richness gradient associated with soil pH and calcium content in Temperate Deciduous Forests to ask whether phylogenetic perspectives might provide insight to the origins of this diversity gradient. We sampled forest vegetation in fifty 0.1 ha located across New York and New England on sites ranging from acidic, nutrient-poor soils to circumneutral, calcium-rich soils. For each plot, we calculated several estimates of the understory plant community’s mean phylogenetic ‘depth’ by averaging the nodal root distance, family age, or order age for all Angiosperm species present. To capture aspects of community ecological structure, we also calculated abundance-weighted estimates of plot mean phylogenetic depth. Species richness and estimates of plot phylogenetic depth were significantly correlated with soil calcium content, with plots on fertile, high calcium soils containing both greater numbers of species and a disproportionally greater representation of species from early-diverging Angiosperm lineages, such as families like the Aristolochiaceae, Berberidaceae, Lauraceae, Magnoliaceae, and Ranunculaceae. Significant correlations were also found between soil calcium content and estimates of phylogenetic depth weighted by species’ relative abundances, indicating that early-diverging Angiosperm lineages also tended to be more dominant in species-rich communities on high calcium soils. These patterns suggest that fertile, calcium-rich soils in mesic Temperate Deciduous Forests may have been an important early habitat niche for Angiosperm colonization of temperate climates and that the dominance of early-diverging lineages in these habitats today may reflect long-term niche incumbency. The results highlight the potential for long-term, large-scale evolutionary processes to play a significant role in determining the structure and diversity of contemporary ecological communities.
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1 - Smith College, Dept. of Biological Sciences, Clark Science Center, 44 College Lane, Northampton, MA, 01063, USA
2 - Cornell University, Department of Ecology & Evolutionary Biology, Corson Hall, Ithaca, New York, 14853, USA
temperate deciduous forest
Presentation Type: Oral Paper:Papers for Sections
Location: 552A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 3:45 PM