| Abstract Detail
Ecology Chapman, Julia [1], McEwan, Ryan [1]. Tree Functional and Phylogenetic Diversity Across Topographic Gradients in an Old-growth Appalachian Forest. Ever-increasing anthropogenic threats to biodiversity have created an urgent need to broaden our understanding of diversity and the factors that influence it. The widely used taxonomic approaches to quantifying diversity (e.g. Shannon index, species richness) treat every species as a unique entity, ignoring the morphological and physiological variations that may be differentially important to ecosystem function. Alternative approaches include phylogenetic diversity, which is based on the principle that closely related species tend to occupy similar niches due to their similar structure and function, and functional diversity, which relies on measurement of traits that are representative of certain aspects of species’ niches, such as shade- and drought-tolerance. We utilized both phylogenetic and functional diversity measures to further understand the role of local topographic variation in structuring tree communities within an old-growth Appalachian forest. Decadal sampling data from 1979 and 2010 were divided into midstory (2.5–25 cm diameter at breast height) and overstory (>25 cm dbh) strata. Standardized effect sizes of Mean Pairwise Distance (MPD) and Mean Nearest Taxon Distance (MNTD) were calculated to represent phylogenetic diversity within each of 80 plots. Functional richness, evenness, and dispersion were calculated for each plot based on specific leaf area, maximum height, leaf nitrogen content, wood density, and seed mass. Multiple regression was used to test for relationships between these diversity measures and topographic variables (% slope, aspect, elevation) for each stratum and sampling year combination. In all but one regression model, phylogenetic diversity exhibited a significant relationship only with elevation (all r2 ≤ 0.34, P < 0.001), where higher elevation plots tending to have lower phylogenetic diversity. Aspect and elevation together were only significant in one phylogenetic diversity model (midstory 2010 MPD; model r2 = 0.29, P < 0.000001), and slope percentage was not a significant factor in any of the regression models. Functional evenness was not significantly related to any of the topographic variables at either time point for either stratum. Functional richness and dispersion displayed inconsistent relationships with the topographic variables across the four time-strata groupings, but where significant, both measures were negatively related to aspect and elevation, and positively related to slope. That is, functional diversity tends to be higher at low elevations, north-facing aspects, and on steeper slopes. Overall, our results suggest that the most xeric areas of our site exert an environmental filtering effect where mature communities contain species with similar adaptations for surviving in xeric conditions.
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1 - University of Dayton, Biology, 300 College Park, SC 211, Dayton, OH, 45469, USA
Keywords:
functional diversity
phylogenetic diversity
old-growth
topography
diversity.
Presentation Type: Oral Paper
Session: 15, Ecology Section: Forest Ecology
Location: 104/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 8:45 AM
Number: 15004
Abstract ID:731
Candidate for Awards:None |
