Large-scale pattern of seed plant richness in mainland of China

Background/Question/Methods: Plant richness varies greatly through space. Determining why these variations occur has been a core objective for a long time in ecology and biogeography. A primary goal of contemporary ecology is to identify the factors responsible to this variation.We aim to examine the spatial distribution pattern of seed plants in mainland of China and to determine what environmental factors are most closely related to the species richness pattern. The mainland of China was divided into 241 quadrats of 2° latitude by 2° longitude. The numbers of species, genus and family of seed plant occurring in each quadrat were counted based on available records. Climatic attributes of each quadrat were obtained from the 30-year records of 830 county’s meteorological stations.

Results/Conclusions: The results showed that the maximum plant species richness occurs in the south of Yunnan province, while the minimum plant species richness is found on Qinghai-Tibetan Plateau. Plant species richness is significantly correlated with almost all factors examined. The annual mean precipitation is the most significant factor, and other significant factors are monthly mean temperature of January, minimum temperature, sunshine ratio, annual mean temperature, annual mean relative humidity, latitude, annual potential evapotranspiration, frost-free period etc. The pattern of species richness of seed plant in mainland of China is a result of a comprehensive effect of multi-factors, among which the annual precipitation is the most important. This differs from the energy-hypothesis that species richness is most strongly correlated with annual evapotranspiration. Energy-hypothesis is applicable to the interpretations of biogeographical patterns of richness for trees and vascular plants in North America, and is applicable to that of trees in Great Britain and Ireland. China is much more continental compared with North America and British Isles. Therefore, it is easy to understand that water-conditions in habitats are more significant for plant growth in China, especially in the west of China. The family and genus richness of seed plants have the similar patterns to that of species richness in China.