云南中度退化的喀斯特天坑草地植物群落优势种种间关系

喀斯特天坑作为独特的宏大地表负地形,其坑底生境与外界环境相互独立,呈现出独特的植物群落格局及特征.本研究选取云南沾益天坑群中可进入性较强的中度退化天坑--巴家陷塘为对象,筛选出重要值大于1的优势种,结合总体关联性分析、χ²检验、AC联结系数及Spearman秩相关系数对巴家陷塘退化天坑植物群落中11种优势种的种间关联性和相关性进行研究.结果表明: 巴家陷塘退化天坑植物群落种间联结指数VR=1.377>1,总体呈显著正关联,但正负关联差异较大,阳生型植物和阴生型植物呈极显著负关联,现阶段仍具有独立的分布格局,但呈逐渐趋于稳定的趋势;Spearman分析中种间正相关对数(26对)少于种间负相关对数(29对),结合天坑微环境的差异,将退化天坑的优势物种划分为3个生态种组,群落总体呈现出一定的圈层分布规律.

Interspecific relationships of dominant species in the grassland community of moderately degraded tiankeng of Yunnan,China.

Karst tiankeng is a special grand negative landform. The environment of tiankeng inside are independent of that outside, showing a unique characteristics of plant community. Taking a moderately degraded tiankeng with good accessibility, Bajiaxiantang as the focus, the dominant species with importance value >1 were selected to clarify the interspecific association of 11 dominant species by the multi-disciplinary approach including the variance ratio (VR) of overall association, χ² test, association coefficient (AC) and Spearman rank correlation coefficient. The results showed that VR of overall association in this grassland community was 1.377 (which was larger than 1), indicating that this community had overall significantly positive interspecific association. Given the great difference between the positive and negative association and significantly negative correlation between heliophiles and sciophiles, the community had independent distribution. The number of positive pairs of species (26) was less than that with negative correlation (29) in Spearman correlation analysis. Combined with the difference of tiankeng’s micro-environment, dominant plant species of degraded tiankeng could be divided into three ecological groups. The grassland community in tiankeng showed circle distribution pattern.