Scale-dependent relationships between tree species richness and ecosystem function in forests
The official blog of the journal named the paper Editor’s Choice for the edition.
This is a high profile acknowledgment considering that the CTFS-ForestGEO network was mentioned by name for being the leader in global forest plots. Plots stretch from Latin America and Africa to the Czech Republic and Malaysia. This paper did not focus on any one site, but on different sites around the world that are similar in size.
Authors of the article include: Ryan A. Chisholm, Helene C. Muller-Landau, Kassim Abdul Rahman, Daniel P. Bebber, Yue Bin, Stephanie A. Bohlman, Norman A. Bourg, Joshua Brinks, Sarayudh Bunyavejchewin, Nathalie Butt, Honglin Cao, Min Cao, Dairon C_ardenas, Li-Wan Chang, Jyh-Min Chiang, George Chuyong, Richard Condit, Handanakere S. Dattaraja, Stuart Davies, Alvaro Duque, Christine Fletcher, Nimal Gunatilleke, Savitri Gunatilleke, Zhanqing Hao, Rhett D. Harrison, Robert Howe, Chang-Fu Hsieh, Stephen P. Hubbell, Akira Itoh, David Kenfack, Somboon Kiratiprayoon, Andrew J. Larson, Juyu Lian, Dunmei Lin, Haifeng Liu, James A. Lutz, Keping Ma, Yadvinder Malhi, Sean McMahon, William McShea, Madhava Meegaskumbura, Salim Mohd. Razman, Michael D. Morecroft, Christopher J. Nytch, Alexandre Oliveira, Geoffrey G. Parker, Sandeep Pulla, Ruwan Punchi-Manage, Hugo Romero- Saltos, Weiguo Sang, Jon Schurman, Sheng-Hsin Su, Raman Sukumar, I-Fang Sun, Hebbalalu S. Suresh, Sylvester Tan, Duncan Thomas, Sean Thomas, Jill Thompson, Renato Valencia, Amy Wolf, Sandra Yap, Wanhui Ye, Zuoqiang Yuan and Jess K. Zimmerman
1. The relationship between species richness and ecosystem function, as measured by productivity or biomass, is of long-standing theoretical and practical interest in ecology. This is especially true for forests, which represent a majority of global biomass, productivity and biodiversity.
2. Here, we conduct an analysis of relationships between tree species richness, biomass and productivity in 25forest plots of area 8–50 ha from across the world. The data were collected using standardized protocols, obviating the need to correct for methodological differences that plague many studies on this topic.
3. We found that at very small spatial grains (0.04 ha) species richness was generally positively related to productivity and biomass within plots, with a doubling of species richness corresponding to an average 48% increase in productivity and 53% increase in biomass. At larger spatial grains (0.25 ha, 1 ha), results were mixed, with negative relationships becoming more common. The results were qualitatively similar but much weaker when we controlled for stem density: at the 0.04 ha spatial grain, a doubling of species richness corresponded to a 5% increase in productivity and 7% increase in biomass. Productivity and biomass were themselves almost always positively related at all spatial grains.
4. Synthesis. This is the first cross-site study of the effect of tree species richness on forest biomass and productivity that systematically varies spatial grain within a controlled methodology. The scale-dependent results are consistent with theoretical models in which sampling effects and niche complementarity dominate at small scales, while environmental gradients drive patterns at large scales. Our study shows that the relationship of tree species richness with biomass and productivity changes qualitatively when moving from scales typical of forest surveys (0.04 ha) to slightly larger scales (0.25 and 1 ha). This needs to be recognized in forest conservation policy and management.