不同石漠化程度岩溶峰丛洼地系统景观格局的比较

利用花江岩溶峡谷区南坡不同石漠化程度的 5 个独立的岩溶峰丛洼地系统景观要素的实测数据,分析了多样性、优势度、破碎度、分离度等景观格局指标的变化规律及其所指示的生态学意义。结果表明,这些指标在不同峰丛洼地系统都能较好地评价石漠化过程中景观格局的动态变化规律,对分析石漠化土地的发展趋势具有较好的指示意义。但多样性指数、优势度指数、均匀度指数也与各峰丛洼地系统的景观基质有关,在不同石漠化程度的峰丛洼地系统中,反映的景观生态意义是不一样的。本文的研究情况表明,岩溶生态系统石漠化过程更大程度上决定于斑块类型的分布部位、破碎度与连接度等,而不仅仅是裸岩与植被面积的绝对数量比例。景观格局分析不仅强调面积,而且还考虑所研究石漠化土地的空间分布特征(格局)、景观组成特点与石漠化过程的关系和对石漠化的影响,在石漠化程度判定和石漠化指标的研究中景观格局是一个不可忽视的问题。

A COMPARATIVE STUDY ON LANDSCAPE PATTERNS OF PEAK CLUSTER DEPRESSIONS DIFFERENT IN ROCK DESERTIFICATION DEGREE

Based on field investigation, analysis was done of the landscape conditions and indexes and their ecological significance of 5 separate peak cluster-depressions, different in rock desertification degree at the southern slope of the Huajiang Karst Gorge. Results indicate that the landscape spatial patterns of all the 5 peak cluster- deperssions have no direct relation with landform grade and physiognomy positions, and the cause of the formation of patches is diversification. The diversity index shows a decreasing trend while the dominance index an increasing trend significantly with the increase in rock desertification degree. The landscape of potential rock desertified peak cluster-depressions is more even than lightly or moderately rock desertified peak cluster-depressions, but the most fragmentized among all peak cluster-depressions. The evenness index increases when rock desertification develops further, or when fragmentation of the landscape increases. With its index of isolation rising, the patch area of naked rock increase gradually. But when the index of isolation of grasslands, shrub and woodland increases their patch area decreases. The landscapes and development modes of potential and strong peak cluster-depressions are typical of rock desertification in the karst mountain areas, Southwest China. Therefore, landscape patterns, landscape diversity, and patches closely correlating with rock desertification process must be taken into account in the assessment of the rock desertification degrees.