| To reveal main driving factors influencing the primary productivity of natural grassland in Ningxia, the principal component analysis of factors like average annual temperature, average temperature from April to September,accumulative temperature ≥0℃, annual precipitation (mm), April-September rainfall (mm), annual evaporation (mm), moisture, sunshine time (h) and the frost-free period (d) in arid and semi-arid areas was carried out. Results showed that factors influencing the primary productivity of arid grassland in Ningxia were moisture, heat, light and dryness, whose contribution rates were 50.17%, 21.82%, 11.84% and 8.80%, respectively. Of the factors above, heat had negative effects while dryness was unimportant; factors influencing primary productivity of semi -arid grassland were accumulative
temperature-light, and moisture, whose contribution rate were 63.76% and 31.50%, moreover, the accumulative temperature-light factor had negative effects. Primary productivity of natural grassland is significantly affected by many factors. Among the factors, water plays the most important role in arid grassland. In contrast, accumulative temperature-light plays the most important role in the semi-arid natural grassland. |
