A comparative researches on landscape pattern changesin different rock desertification peak cluster-depressions
不同石漠化程度岩溶峰丛洼地系统景观格局的比较

Karst rocky desertification is a kind of land degradation which has happened in fragile karst mountain ecosystem in Southwest China. The unsuited matching at vertical direction and unreasonable special distribution at horizontal direction of landscape use make the landscape degradation a major problem in karst mountain areas. But little is being understood about the interrelation between the spatial distribution of rocky desertified land and the rocky desertification processes. This paper analyzes the ecological conditions of 5 special peak cluster-depressions which are at different desertification degrees on the southern slope of Huajiang karst gorge based on field investigation, the change of landscape pattern indexes and their ecological significance, in order to understand the ecological spatial character and evolving procedure of karst mountains from landscape ecological viewpoint. Results indicate that the diversity index, dominance index and evenness index relate closely to the landscape matrix of peak cluster-depressions, and show different ecological significance in different rocky desertified peak cluster-depressions. With the increase of rocky desertification intensity, the diversity index is in a decreasing trend while dominance index in an increasing trend significantly, the evenness index decreases firstly and then increases when rocky desertification develops further, the isolation and patch area of naked rock increase gradually but isolation of grasslands, shrub and woodlands increases while their patches area in a reduction. The landscape of potential rocky desertified peak cluster-depressions is even more seriously fragmentized than light and moderate rocky desertified peak cluster-depressions, and fragmentation is most in all peak cluster-depressions. The landscape patterns and development modes of potential rocky desertified and strong rocky desertified peak cluster-depressions represent two typical types of rocky desertification in southwest karst mountain areas. This paper shows that the processes of karst ecosystem rocky desertification depends on the distribution, fragmentation and conjunction, not merely the absolute quantity scale of naked rocks and vegetation. The analysis of landscape pattern emphasizes not only area, but also the relations and influence among rocky desertification processes, the spacial pattern of rocky desertification and landscape element character, therefore, landscape should not be neglected in the studies of rocky desertification degree and indexes, landscape patterns, landscape diversity and patches closely correlating with rocky desertification process must be taken into account in the assessment of the karst rock desertification degrees.