Is plant biodiversity driven by decomposition processes? An emerging new theory on plant diversity

Abstract. Diversity of forest trees ranges from monospecific stands to the astonishing richness of tierra firma tropical forests. Such patterns are observed along gradients of latitude, altitude, soil fertility and rainfall. So far, the proposed coexisting mechanisms do not provide a comprehensive and unequivocal explanation of these patterns at the community level. We propose a new theory linking species diversity with organic matter cycle and negative plant-soil feedback induced by litter autotoxicity. This approach focuses on resource-waste rather than resource-only dynamics. High diversity does occur where litter decomposition is rapid and ecosystem nutrient cycles are closed. On the other hand, single species dominance is found where litter decomposition is slow and/or autotoxicity is removed from the nutrient cycle pathway. Unlike previous theoretical views, the one we present proves potentially capable of explaining differences in species diversity both along environmental gradients and within the tropics.