Fluctuation theory and the practice of grassland vegetation in the northern farming-pastoral ecotones of China

Abstract

Vegetation fluctuation is an important part of vegetation dynamics. The characteristics of vegetation fluctuation are quite different between grassland and forest communities. By inferring from ecologic and statistical information, grassland vegetation fluctuation and its fluctuation ratio were defined, and an equation for the fluctuation ratio was established for the first time with the fluctuation coefficients specified via expert weighting method. The quantitative grassland vegetation fluctuation and its fluctuation ratio between the years 2002 and 2006 in Yanchi County, Ningxia, northwestern China, in the northern farming-pastoral ecotones, were studied. Results showed that the largest positive fluctuation ratio of 0.685, implying the best vegetation growth in recent years occurred in 2003, while the most negative fluctuation ratio of -1.098, i.e., the worst vegetation growth during this period, occurred in 2005.

Keywords

farming-pastoral ecotones of China / grassland vegetation / fluctuation / fluctuation ratio