Phylogenetic structure of angiosperm trees in local forest communities along latitudinal and elevational gradients in eastern North America |
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| Authors: | Hong Qian Jian Zhang Brody Sandel Yi Jin |
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| Institution: | 1. CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Inst. of Botany, Chinese Academy of Sciences, Kunming, China;2. Tiantong National Forest Ecosystem Observation and Research Station and School of Ecological and Environmental Sciences, East China Normal Univ, Shanghai, China
Shanghai Inst. of Pollution Control and Ecological Security, Shanghai, China;3. Dept of Biology, Santa Clara Univ, Santa Clara, CA, USA;4. State Key Laboratory of Plant Physiology and Development in Guizhou Province, School of Life Sciences, Guizhou Normal Univ, Guiyang, China |
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| Abstract: | Latitudinal and elevational gradients both represent thermal gradients. Assessing the consistency of the relationships between phylogenetic structure and climate between latitudinal and elevational gradients can provide insight into the mechanisms driving assembly of species from regional pools into local assemblages. The aim of this study is to compare patterns of phylogenetic structure measures for angiosperm tree species between latitudinal and elevational gradients, using a dataset of angiosperm tree species in 14 092 forest plots in eastern North America. We assessed whether these two gradients produce similar relationships between climate and phylogenetic structure, hypothesizing that they should differ in magnitude but not direction. We used correlation and regression analyses to assess the relation of measures of phylogenetic structure to elevation, latitude and climatic variables, which included minimum temperature, temperature seasonality, annual precipitation and precipitation seasonality. We found that 1) phylogenetic relatedness of angiosperm trees increases with decreasing temperature along both latitudinal and elevational gradients but the relationship between phylogenetic relatedness and temperature is steeper for elevational gradients than for latitudinal gradients; 2) the tip-weighted metric of phylogenetic relatedness (nearest taxon index) is more strongly correlated with climatic variables than the basal-weighted metric of phylogenetic relatedness (net relatedness index); 3) winter cold temperature exerts a stronger effect on community assembly of angiosperm trees than does temperature seasonality. These results suggest that winter cold temperature, rather than temperature seasonality, drives phylogenetic structure of plants in local forest communities, and that species distributions along elevational gradients are more in equilibrium with temperature, compared with those along latitudinal gradients. |
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| Keywords: | cold tolerance community assembly environmental filtering niche conservatism temperate forests thermal gradients |
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