Below-ground competition drives the self-thinning process of Stipa purpurea populations in northern Tibet

摘要

QuestionsAbove-ground, below-ground and individual mass-density relationships for perennial herbs were examined along a natural precipitation gradient in northern Tibet. We asked: (1) how do the self-thinning exponents respond to variation in precipitation; and (2) what mechanisms drive the observed population self-thinning?