[Relationships between Kobresia's species richness and climatic factors in China].

Based on the information from collected literatures, this paper defined the geographical distribution of Kobresia in China, and analyzed the relationships between the Kobresia's species richness and climatic factors. The Kobresia in China had higher species richness on the borders of Yunnan Province, Sichuan Province, and Tibet Autonomous Region and in the southeast Qinghai Province and Himalayas, with a denser and wider distribution in the areas of < 40 degrees N, 85 degrees-105 degrees E and > altitude 2500 m, or the areas of lower or medium thermal factors, medium precipitation, medium aridity and humidity, or medium sunshine duration. The species richness was significantly negatively correlated with the mean, maximum, and minimum air temperature in July and the mean air temperature in summer (P < 0.05), and well corresponded to the isolines of warmth index, annual biotemperature, extreme maximum air temperature, air temperature in summer, and mean, maximum, and minimum air temperature in July. Multiple linear regression analysis indicated that the maximum air temperature in July and the precipitation in spring had significant effects on the species richness (P<0.05) , with the greatest contribution of the maximum air temperature in July. Stepwise regression analysis indicated that the mean air temperature in July and the mean annual maximum and extreme maximum air temperature had significant effects on the species richness (P < 0.05), and the principal component regression analysis indicated that the extreme maximum air temperature, air temperature in July and summer, Thornthwaite aridity index, sunshine hours in April-October, precipitation in summer and autumn, and annual precipitation had greater effects on the richness. The air temperature, precipitation, and sunshine hours in growth season as well as the extreme maximum air temperature, annual precipitation, and soil moisture content were the main factors affecting the geographical distribution of Kobresia in China.