Pervasive phosphorus limitation of tree species but not communities in tropical forests

London

2018

367-370

Sonderdruck

203617

Phosphorus availability is widely assumed to limit primary productivity in tropical forests1,2, but support for this paradigm is equivocal3. Although biogeochemical theory predicts that phosphorus limitation should be prevalent on old, strongly weathered soils4,5, experimental manipulations have failed to detect a consistent response to phosphorus addition in species-rich lowland tropical forests6,7,8,9. Here we show, by quantifying the growth of 541 tropical tree species across a steep natural phosphorus gradient in Panama, that phosphorus limitation is widespread at the level of individual species and strengthens markedly below a threshold of two parts per million exchangeable soil phosphate. However, this pervasive species-specific phosphorus limitation does not translate into a community-wide response, because some species grow rapidly on infertile soils despite extremely low phosphorus availability. These results redefine our understanding of nutrient limitation in diverse plant communities and have important implications for attempts to predict the response of tropical forests to environmental change.