Response of plant community to nitrogen and phosphorous additions in sub-alpine meadow of the Qinghai-Tibetan Plateau

• 1、School of Life Sciences, Lanzhou University, LanZhou 730000
• 2、School of Life Sciences,Lanzhou University

Abstract：The objective was to investigate the effects of nitrogen (N) and phosphorus (P) addition treatment combination on aboveground plant productivity and species richness in sub-alpine meadow of the Qinghai-Tibetan Plateau, Gannan, China. The results showed that (1) nitrogen (N) addition alone significantly increased aboveground plant productivity and decreased species richness, but phosphorus (P) addition alone did not be, (2) interactive addition of nitrogen (N) and phosphorus (P) affected strongly aboveground plant productivity and species richness than addition of nitrogen (N) and phosphorus (P) alone, (3) there was a significant linear negative relationship between aboveground plant productivity and species richness, light penetration, and linear positive relationship between species richness and light penetration. The results suggested that sub-alpine meadow ecosystem in Gannan was nitrogen (N) limitation, but not phosphorus (P). Moreover, fertilization led to competition shifts from belowground soil resource to aboveground light resource, and the aboveground light competition results in random species loss. That is to say, aboveground plant productivity and community coverage increased with fertilization, and light penetration in community canopy intensified, consequently, small individuals of all species died under intense light competition led to local extinction of initially rare species or stochastic loss of species from plots.

Keywords： Ecology nitrogen (N) and phosphorus (P) additions light competition species richness aboveground plant productivity random loss sub-alpine meadow