What is it about?
The availability of nutrients to plants depends on many different factors that can be divided into abiotic (geology, rainfall) and biotic (animals, plants, microbes). The question addressed here is how much influence organisms have on their own environment in comparison to the abiotic template. We found that organisms have a higher impact on the availability of different nutrients than environmental factors like rainfall. Different vegetation types (trees, bunch grassland and grazing lawns) that occurred several meters from each other and therefore sharing the same geological origin and climate differed more in nutrient-related indices than similar vegetation types that were situated many kilometers away under different rainfall conditions.
Why is it important?
Humans are altering the abiotic template worldwide through changes in climate change (CO2 emission) and nutrient cycling (fertilization). When the functioning of ecosystems is dominated by environmental conditions, this would suggest that large changes will occurs as a result of human impact. However, when organisms can change the local availability of water and nutrients, this would increase the robustness of ecosystems against human imposed environmental changes. The results of our study suggest that local management and the protection of key organisms will help to increase the robustness of ecosystems.
Many ecologists still view (savanna) ecosystems as being primarily determined by abiotic factors such as rainfall and soil proporties. However, this study shows that biotic processes are very important in shaping the structure and functioning of savanna ecosystems. This has important consequences for their management and conservation.