南方典型红壤区生态脆弱性与土壤侵蚀的演化关系

Evolutionary Relation Between Ecological Vulnerability and Soil Erosion in the Typical Reddish Soil Region of Southern China

通过RUSLE获取1999—2010年福建长汀县土壤侵蚀基础数据,选择坡度、土壤可蚀性、降雨侵蚀力、地形起伏度、植被覆盖度和人口密度6个指标,利用土壤侵蚀强度指数分析11 a间土壤侵蚀和生态脆弱性二者变化的协同性。结果表明:研究区中部与东南部水土流失严重、生态脆弱性程度高,二者同期分布面积比例由微弱往严重程度减小,二者各等级空间分布具有较强相关性;1999—2010年间,各侵蚀等级发生减弱面积比例达81.71%~99.80%,各脆弱等级发生减弱面积比例达43.96%~73.83%,土壤侵蚀程度降低,生态脆弱性减轻,11 a间生态环境恢复比水土治理难度大;随着各脆弱性等级转化程度的不同,土壤侵蚀强度指数(Ei)表现出规律性的变化区间,分别为[-95,+44]、[-147,-104]∪[+45,+126]、[-233,-149],其强度变化区间与脆弱度演化呈现高度协同效应。

This study quantitatively determined the amount of soil erosion of the county in 1999 and 2010 respectively, using the Revised Universal Soil Loss Equation （RUSLE）. Slope, K factor （soil erodibility）, R factor （rainfall erosivity）, topography, vegetation coverage and population density were selected as ecological factors for the synergetic assessment between soil erosion and ecological vulnerability based on soil erosion intensity index （Ei） during the past 11 years. The results showed that there was strong correlation in each geographical distribution of grades between soil erosion and ecological vulnerability. There were serious soil erosion and high degree of ecological vulnerability in central and southeastern Changting County, and the proportion of the distribution area decreased gradually from weak grade to severe grade in the same period. From 1999 to 2010, the reduced proportion of each soil erosion grade and each ecological vulnerability grades was from 87.71% to 99.80%, from 43.96% to 73.83%, respectively. The findings indicated the degree of soil erosion and ecological vulnerability was reduced, and the restoration of ecological environment was more difficult than control of soil erosion over the past 11 years. With the difference of degree of ecological vulnerability transform, the regular interval of Ei changing was presented as [-95, ＋44], [-147, -104]∪[＋45, ＋126], [-233, -149], respectively, which showed highly synergistic effect with the evolution of ecological vulnerability.