GEOGRAPHICAL RESEARCH ›› 2002, Vol. 21 ›› Issue (3): 391-398.doi: 10.11821/yj2002030015

• Earth Surface Processes • Previous Articles    

The relation between coupling among the principal components of desertification factors and desertification in rear hills of Bashang since 1950

SUN Wu, LI Bao sheng   

  1. Department of Geography, South China Normal University, Guangzhou 510631, China
  • Received:2001-09-18 Revised:2002-01-20 Online:2002-06-15 Published:2002-06-15

Abstract:

Based on the EOF, the paper takes 6 factors such as precipitation, climatic output of grain, the relative change of livestock, wind speed, days of yearly gale and climatic wind erosive force as fluctuating factors of desertification to analyze their principal components since 1950 in rear hills of Bashang. The result shows that despite their synchronization in fluctuation for the dominance of rainfall, they can be decomposed into three relative independent series of wind, cattle and rainfall according to the REOF. Hereby, we choose four factors of climatic output of grain(O), the number of livestocks(A), days of yearly gale(G) and climatic wind erosive force(C′) as the ones which mainly influence desertification, and calculate them in the same weight coupling(C) in biological year by two different types of pastoral area and interlock area of farming and pasturing(IAFP) In pastoral areaC(%)=(G+C′+A)*3 -1 in IAFPC(%)=(G+C′+A+O)*4 -1 The coupling(C) in the 3 year smoothed average among the principal components of desertification factors fluctuated between 25%~100% since 1950, and maintained the level of 75% after 1965, but it reached the highest period during 1967~1977. The conflict between pasture and livestock mostly took place in the two periods of 1965~1975 and 1986~1990, in which there was deficient rainfall in the study area. As the resonance of the higher annual wind speed, much more days of yearly gale and less rainfall during 1965~1975, soil erosion experienced higher risk. Compared with the human contribution to the development of desertification, natural environment just forms a background, it is the irrational reclamation that plays the leading role, and the sustainable development of desertification in the mid 1980s with much more rain fall speaks well for the leading role of human played in this region. Nothing but the coupling between irrational land use and strong wind erosion during 1965~1975 greatly promotes the overspreading of desertification. Two different fluctuating types of Hebei province and Inner Mongolia are identified in the study area.

Key words: desertification factors, principal components, coupling