关键词: 土壤养分, 空间异质性, 生态系统, 景观性质

Abstract: Based on the 1961-2008 daily precipitation data from 110 meteorological stations in South China, the spatiotemporal characteristics of extremely heavy precipitation frequency in summer over South China were studied by the ways of REOF, trend coefficient, linear trend, M-K test and variance analysis, and the extremely heavy precipitation thresholds were determined, according to the 95th percentiles of non-parametric distribution for different stations. The extremely precipitation events frequency anomaly in summer over South China was negative from late 1970s to early 1990s, and was positive after mid-1990s. Six sub-regions were divided, according to the spatial characteristics of extremely heavy precipitation frequency over South China. A significant upward trend of the extremely heavy precipitation events in summer appeared over northeast Guangxi, southeast Guangxi and west Guangdong, and south Hainan. Over east Guangdong, west Guangxi, and Leizhou area, the trend of extremely heavy precipitation events in summer was on the low side in the 1980s, and on the higher side between the 1990s and the beginning of 21st century. The periodic variation of the extreme precipitation frequency in summer in the six sub-regions was significant, with 23 and 21 years in long period, 17, 16, and 12 years in mid-term period, and 5 and 4 years in short cycle. Five of the six sub-regions appeared a significant increase in extreme precipitation frequency in 1990s.

Key words: Soil nutrients, Spatial heterogeneity, Ecosystem, Landscape characteristics