Demographic composition, not demographic diversity, predicts biomass and turnover across temperate and tropical forests
Jessica Needham, Daniel J. Johnson, Kristina J. Anderson‐Teixeira, Norman A. Bourg, Sarayudh Bunyavejchewin, Nathalie Butt, Min Cao, Dairón Cárdenas, Chia‐Hao Chang‐Yang, Yu‐Yun Chen, George B. Chuyong, H. S. Dattaraja, Stuart J. Davies, Álvaro Duque, Corneille E. N. Ewango, Edwino S. Fernando, Rosie A. Fisher, Christine Fletcher, Robin B. Foster, Zhanqing Hao, Térese B. Hart, Chang‐Fu Hsieh, Stephen P. Hubbell, Akira Itoh, David Kenfack, Charles D. Koven, Andrew J. Larson, James A. Lutz, William J. McShea, Jean‐Remy Makana, Yadvinder Malhi, Toby R. Marthews, Mohizah Bt. Mohamad, Michael D. Morecroft, Natalia Norden, Geoffrey G. Parker, Ankur Shringi, Raman Sukumar, H. S. Suresh, I‐Fang Sun, Sylvester Tan, Duncan W. Thomas, Jill Thompson, María Uriarte, Renato Valencia, Tze Leong Yao, Sandra Yap, Zuoqiang Yuan, Yuehua Hu, Jess K. Zimmerman, Daniel Zuleta, Sean M. McMahon
Abstract
The growth and survival of individual trees determine the physical structure of a forest with important consequences for forest function. However, given the diversity of tree species and forest biomes, quantifying the multitude of demographic strategies within and across forests and the way that they translate into forest structure and function remains a significant challenge. Here, we quantify the demographic rates of 1961 tree species from temperate and tropical forests and evaluate how demographic diversity (DD) and demographic composition (DC) differ across forests, and how these differences in demography relate to species richness, aboveground biomass (AGB), and carbon residence time. We find wide variation in DD and DC across forest plots, patterns that are not explained by species richness or climate variables alone. There is no evidence that DD has an effect on either AGB or carbon residence time. Rather, the DC of forests, specifically the relative abundance of large statured species, predicted both biomass and carbon residence time. Our results demonstrate the distinct DCs of globally distributed forests, reflecting biogeography, recent history, and current plot conditions. Linking the DC of forests to resilience or vulnerability to climate change, will improve the precision and accuracy of predictions of future forest composition, structure, and function.