J Plant Ecol ›› 2011, Vol. 4 ›› Issue (3): 138-146 .DOI: 10.1093/jpe/rtq031

• Research Articles • Previous Articles     Next Articles

Root-shoot competition interactions cause diversity loss after fertilization: a field experiment in an alpine meadow on the Tibetan Plateau

Wei Li1,2, Shujun Wen2, Wenxiang Hu2 and Guozhen Du2,*   

  1. 1 College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, People's Republic of China; 2 MOE Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, People's Republic of China
  • Received:2010-06-22 Accepted:2010-10-25 Published:2011-08-24
  • Contact: Du, Guo-zhen

Root-shoot competition interactions cause diversity loss after fertilization: a field experiment in an alpine meadow on the Tibetan Plateau

Abstract: Aims A decrease in species diversity after fertilization is a common phenomenon in grasslands; however, the mechanism causing it remains highly controversial. The light competition hypothesis to explain loss of diversity has received much attention. The aim of the present paper was to test this hypothesis.
Methods Fertilization was used to control above- and belowground resources simultaneously, while shade was used to control aboveground resource in an alpine meadow on the Tibetan Plateau. Univariate general linear models was used to estimate the effects of fertilization and shade on above- and belowground vegetation characteristics, including photosynthetically active radiation (PAR) in the understory, aboveground biomass, belowground biomass, R:S ratio, species richness and Simpson's diversity index.
Important findings PAR was similar in the understory of shaded and fertilized plots, but only fertilization reduced species richness and diversity, suggesting that light competition alone could not explain diversity loss after fertilization. The root biomass and R:S ratio had a significant increase in shaded plots, but the richness and diversity did not change, suggesting that root competition alone also could not explain diversity loss after fertilization in this community. Our results illustrated that the root–shoot competition interactions, investigated from a functional groups perspective, should be the most reasonable explanation leading to the diversity loss due to fertilization.

Key words: Alpine meadow, diversity loss, functional groups, interactions, light competition hypothesis, shade, Tibetan plateau

摘要:
Aims A decrease in species diversity after fertilization is a common phenomenon in grasslands; however, the mechanism causing it remains highly controversial. The light competition hypothesis to explain loss of diversity has received much attention. The aim of the present paper was to test this hypothesis.
Methods Fertilization was used to control above- and belowground resources simultaneously, while shade was used to control aboveground resource in an alpine meadow on the Tibetan Plateau. Univariate general linear models was used to estimate the effects of fertilization and shade on above- and belowground vegetation characteristics, including photosynthetically active radiation (PAR) in the understory, aboveground biomass, belowground biomass, R:S ratio, species richness and Simpson's diversity index.
Important findings PAR was similar in the understory of shaded and fertilized plots, but only fertilization reduced species richness and diversity, suggesting that light competition alone could not explain diversity loss after fertilization. The root biomass and R:S ratio had a significant increase in shaded plots, but the richness and diversity did not change, suggesting that root competition alone also could not explain diversity loss after fertilization in this community. Our results illustrated that the root–shoot competition interactions, investigated from a functional groups perspective, should be the most reasonable explanation leading to the diversity loss due to fertilization.