Patterns of plant species diversity along an altitudinal gradient and its effect on above-ground biomass in alpine meadows in Qinghai-Tibet Plateau
Zhe Liu;Qi Li;Dongdong Chen;Wenting Zhai;Liang Zhao;Shixiao Xu;Xinquan Zhao;Northwest Institute of Plateau Biology, Chinese Academy of Sciences;University of Chinese Academy of Sciences;Chendu Institute of Biology, Chinese Academy of Sciences;
Changes in plant species diversity along an altitudinal gradient and the relationship between biodiversity and productivity are important issues in ecology, which have not been addressed fully. To clarify the patterns of species diversity and above-ground biomass along an altitudinal gradient in alpine meadows, two representative mountains in Qinghai-Tibet Plateau were chosen as study subjects: Laji Mountain(36°21′ N, 101°27′ E) in Guide County, Hainan Tibetan Autonomous Prefecture and Junmuchang Mountain(34°22′ N, 100°30′ E) in Maqin County, Golog Tibetan Autonomous Prefecture. Plant height, coverage, above-ground biomass, and species diversity with altitude change were investigated. We found that the patterns of above-ground biomass and species diversity along an altitudinal gradient in the two mountain transects are consistent. With an increase in altitude, the above-ground biomass decreased linearly; Shannon-Wiener index, Simpson index and species richness present hump-shaped distributions, with the maximum value found in the middle altitudinal gradient, while the Pielou index increased regularly in a straight line with an increase in altitude. Combined with the present data for the alpine meadows in the Qinghai-Tibet Plateau, we found that species richness shows a hump-shaped curve with the increase in altitude, with the pattern first increasing and then decreased. It may exhibit the universal law of the species distribution in Qinghai-Tibet Plateau. The relationship between above-ground biomass and species diversity in the two mountain transects also appeared uniform: above-ground biomass linearly decreased with increased in Shannon-Wiener index, Simpson index and Pielou index, but it was not associated with species richness. Integrating all data from the two mountain transects, we found that the above-ground biomass was not related to Shannon-Wiener and Simpson indices, however it increases linearly with increases in species richness. Based on the research data in the Qinghai-Tibet Plateau, we found the relationship between above-ground biomass and species richness presented an "S" curve(logistic model).