by Helmholtz Association of German Research Centres
The reason why so many tree species can coexist in species-rich forests has long been a subject of debate in ecology. This question is key to understanding the mechanisms governing the dynamics and stability of forests. An international team of scientists led by the Helmholtz Centre for Environmental Research (UFZ) has now discovered unexpected patterns in the spatial distribution of tree species, as reported in the journal Nature.
Their results suggest that tree species in tropical and temperate forests manifest contrasting coexistence strategies as a result of differences in the patterns of tree clustering and the abundances of tree species.
The data sets are very large: with more than 75 permanent forest dynamics plots in 29 countries worldwide, the Forest Global Earth Observatory network (ForestGEO) of the Smithsonian Tropical Research Institute (STRI) provides excellent forest inventories for investigating the dynamics of forest ecosystems and better understanding the processes that drive the structure and function of forests.
On these 20-to-50-hectare plots, every single tree with a diameter not much larger than a pencil has been identified, measured and mapped every five years, often totaling more than 200 000 trees.
The two UFZ researchers, Dr. Thorsten Wiegand and Prof. Dr. Andreas Huth took a closer look at 21 of these forest megaplots, which cover a gradient from the tropical to the subtropical and temperate zones. Their international team then used the ForestGEO data to analyze the distribution of tree species in the forests and which processes are responsible for their spatial patterns.
