为了解岩溶区土壤允许流失量(T值)与土地石漠化的关系,根据岩溶土壤圈系统论,采用实地调查与GIS空间分析技术,结合贵州碳酸盐岩岩石组合类型测算了T值,并探讨了其对石漠化的影响。结果发现:①岩溶区的T值可分为三大类,在极纯、较纯和不纯的碳酸盐岩地区,T值分别为20、100和250 t·km-2·a-1,在无土可流、完全是石山的地区,T值只有几吨或更低;②在T=20、100和250 t·km-2·a的地区,石漠化发生率分别为29.86%、28.12%和23.25%,石漠化严重度分别为73.55%、60.57%和52.19%。因此,岩溶区的T值总体偏小,且具有多样性和异质性的空间分布特点;在相同社会背景下或不考虑人类活动的干扰差异,T值对石漠化的发生率和严重度有明显影响,T值越低,阈值越小,抗干扰能力越弱,石漠化的发生率越高,程度也越严重。
To understand the relationships between soil loss tolerance (T value) and karst rocky desertification (KRD), T value was calculated using digital-distribution map of carbonate rock assemblages types in this paper, based on pedospheric system theory. And the impacts of T value on KRD were discussed also based on GIS and field survey comprehensively. The results showed that: 1) T values in karst areas can be divided into three categories, which are 20,100 and 250 t·km-2·a-1 respectively in the purest, purer and nonpure carbonate rock areas but only less than 20 t·km-2·a-1 in rocky mountain region. 2) In the three carbonate areas where T=20,100 and 250 t·km-2·a-1 respectively, KRD incidence rates are 29.86%, 28.12% and 23.25% with KRD severity being 73.55%, 60.57% and 52.19%. Therefore, T value in karst areas is very low, and has such characteristics as diversity and heterogeneity in spatial distribution. T value has great impacts on incidence rate and severity of rocky desertified land. In the same social context, or neglecting the differences of human activities, the lower T value is, the smaller the threshold, the weaker anti-jamming capability is, the higher KRD incidence rate is, and the more KRD severity is.
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