Friday, August 6, 2010

PS 96-69: Stoichiometric homeostasis underlies ecosystem structure, functioning, and stability

Qiang Yu1, Quansheng Chen1, James Elser2, Nianpeng He1, Honghui Wu1, Shouren Zhang1, Jianguo Wu2, Yongfei Bai1, and Xingguo Han1. (1) Institute of Botany, Chinese Academy of Sciences, (2) Arizona State University


 Ecosystem structure, functioning, and stability have been a focus of ecological and environmental sciences during the past two decades.  However, the mechanisms that link them are not well understood. We took three approaches to test the relationship of stoichiometric homeostasis with species dominance, ecosystem functioning, and stability.  These involved a two-year field N and P addition experiment, a long-term (27 years) observational data set of grassland excluded from sheep grazing, and a 1200-km spatial transect across the Inner Mongolia grassland. 



 Here we show that species-level stoichiometric homeostasis was consistently positively correlated with dominance and stability on both two-year and 27-year temporal scales and over a 1200-km spatial transect.  At the community level, stoichiometric homeostasis was also positively correlated with ecosystem function and stability in most cases.  Thus, homeostatic species tend to have high and stable biomass; consequently, ecosystems dominated by more homeostatic species have higher productivity and greater stability.  By modulating organism responses to key environmental drivers, stoichiometric homeostasis appears to be a major mechanism responsible for grassland ecosystem structure, functioning, and stability.