Chin J Plant Ecol ›› 2010, Vol. 34 ›› Issue (10): 1125-1131.DOI: 10.3773/j.issn.1005-264x.2010.10.001

Special Issue: 青藏高原植物生态学:群落生态学

• Research Articles •     Next Articles

Effects of nitrogen addition on species richness and relationship between species richness and aboveground productivity of alpine meadow of the Qinghai-Tibetan Plateau, China

ZHANG Jie-Qi, LI Qi, REN Zheng-Wei, YANG Xue, WANG Gang*()   

  1. Key Laboratory of Arid and Grassland Ecology of Ministry of Education, Lanzhou University, Lanzhou 730000, China
  • Received:2010-05-04 Accepted:2010-07-23 Online:2010-05-04 Published:2010-10-31
  • Contact: WANG Gang

Abstract:

Aims Competition for different limiting resources among plant species is the main factor that influences plant community composition, diversity and productivity. Our objective was to investigate the effects of different levels of nitrogen addition on species richness and aboveground productivity of alpine meadow of the Qinghai-Tibetan Plateau, China.

Methods We added nitrogen in a completely randomized block design and measured plant aboveground biomass, species composition, vegetation light penetration and soil pH and NO3--N content in each plot. Regression and analysis of variance were used to analyze the responses of these measures to different levels of nitrogen addition.

Important findings Nitrogen addition changed the soil physical and chemical properties, enhancing the content of NO3--N available resources in the soil, increasing plant cover and reducing vegetation light penetration. With increasing N addition, species richness decreased sharply (p < 0.001). N addition changed aboveground productivity significantly (p < 0.05). With increasing N addition, aboveground productivity increased first then decreased, and grass biomass increased while forb and legume biomasses decreased. There was a significant linear positive relationship between species richness and vegetation light penetration (p < 0.05) and also between aboveground productivity and soil NO3--N content (p < 0.05). The relationship between aboveground productivity and species richness was negative. We suggested that the short term effects of nitrogen addition on community composition and aboveground productivity were determined by the changed soil NO3--N content.

Key words: aboveground productivity, nitrogen addition, soil NO3--N content, species richness, vegetation light penetration