重度退化的喀斯特天坑草地物种多样性及群落稳定性——以云南沾益退化天坑为例

喀斯特天坑是21世纪初命名的宏大地表负地形,其隐域生境为动植物的生长和繁衍提供了良好的条件,近几年来,随着天坑价值的深入挖掘,天坑独特生境特征及其植物群落逐渐得到重视,但现有研究较多关注原生天坑及轻度退化天坑,对退化程度较高且可进入性较强的退化天坑的研究仍相对薄弱。云南大竹菁天坑属于典型的重度退化天坑,可进入性较强,坑底以草地植物群落为主,将其作为退化天坑的代表性区域开展天坑内外植物群落的特征差异及植物群落的稳定程度研究,有利于补充系列天坑现有的理论知识体系,亦能为广大喀斯特区域的生态恢复提供一定的借鉴意义。采用野外采样及数据分析相结合的方法,从定性及定量的角度研究大竹菁退化天坑植被群落特征以及植物群落的稳定程度,研究结果表明:1)退化天坑内草地群落现有14科35属35种,坑外14科30属30种,坑内外物种组成相对多样,两者优势种差异较大,仅一种共优种;2)退化天坑生态系统较为脆弱,坑内外植物群落多样性总体偏低,坑外植物多样性高于坑内植物多样性,但差异不显著,而坑外均匀度却显著高于坑内均匀度;3)坑内外植物群落处于极不相似水平,结构分异明显,群落之间具有较大的生境差异性;4)坑内植物群落种间总体呈正联结性,种间联结较松散,具有一定的独立性,处于正向演替阶段,而坑外呈负关联性,群落较不稳定;5)采用稳定性分析进一步阐释得出,坑内植物群落离稳定状态仍有一定差距,说明受到人为干扰的重度退化天坑生境仍较脆弱。

Species diversity and stability of grassland plant community in heavily-degraded karst tiankeng: a case study of Zhanyi tiankeng in Yunnan, China

Karst tiankeng, named in the early 21st century, is a grand negative landform, and its intrazonal habitat conditions are suitable for animal and plant growth and reproduction. In recent years, with the deep excavation of the scientific and aesthetic value of tiankengs, unique habitat characteristics and plant communities of original and mature tiankeng are valued gradually, but the research of degraded tiankeng is still relatively weak. Dazhujing belongs to the typically, heavily-degraded tiankeng in Yunnan, which has higher accessibility and a grassland community in the bottom section of the tiankengs. Therefore, choosing the study area-Dazhujing to analyze the plant communities on the inner and outer parts of tiankeng, it can improve existing theoretical knowledge system and provide significant reference for the ecological restoration of the karst area. This method of field sampling and statistical analysis had been employed to study the characteristics and degree of stability of karst tiankeng''s plant community from a qualitative and quantitative point of view. The results showed that:1) There were 35 species belonging to 14 families and 35 genera inside the tiankeng, and 30 species belonging to 14 families and 30 genera outside the tiankeng. The species composition was relatively diverse, with only one co-dominant species; 2) Degraded tiankeng had fragile habitats, and plant diversity outside the tiankeng was higher than that inside the tiankeng, however, the difference was non-significant. In contrast, species evenness outside the tiankeng was significantly higher than that inside the tiankeng; 3) The two communities inside and outside the tiankeng were at very dissimilar levels, which had different and diverse structures and significantly different habitats; 4) The plant communities inside the tiankeng had a non-significant positive inter-specific association, were loose, independent, and at the positive succession stage. However, a negative correlation was found between the plant communities outside the tiankeng, which were at an unstable stage; 5) The stability analysis showed that there was still a gap in community stability, which indicated that the ecosystem of the degraded tiankeng was still fragile.