A SIMPLE-MODEL TO EXPLAIN THE DOMINANCE OF LOW-PRODUCTIVE PERENNIALS IN NUTRIENT-POOR HABITATS

This paper addresses the question why inherently low-productive perennials dominate the vegetation in nutrient-poor habitats despite the higher productivity of inherently high-productive perennials at all levels of nutrient availability. A simple model is presented about the biomass and nutrient dynamics of two perennials with an equal nitrogen use efficiency (NUE), but with different values for the components of NUE (A: nutrient productivity; and MRT: the mean residence time of nutrients in the plant). It is assumed that growth is nutrient-limited. This model shows that low-productive, nutrient-conserving species (low A, high MRT) attain at a given level of nutrient availability a higher equilibrium biomass than high-productive species with higher nutrient loss rates (high A, low MRT). However, the high-productive species attain their equilibrium biomass at a faster rate than the low-productive species do.