Nutrient co-limitation and plant diversity

Stanley Harpole (Univ. Halle/UFZ Leipzig): Niche dimensionality provides a general theoretical explanation for biodiversi-ty—more niches, defined by more limiting factors, allow for more ways that species can coexist. Because plant species compete for the same set of limit-ing resources, theory predicts that addition of a limiting resource eliminates potential trade-offs, reducing the number of species that can coexist. Multiple nutrient limitation of plant production is common and therefore fertilization may reduce diversity by reducing the number or dimensionality of belowground lim-iting factors. At the same time, nutrient addition, by increasing biomass, should ultimately shift competition from belowground nutrients towards a one-dimensional competitive trade-off for light. Experimental results point to the importance of understanding dimensionality in ecological systems that are un-dergoing diversity loss in response to multiple global change factors.