云南沾益中度退化天坑草地植物群落水平空间分布特征

规模最为宏大的地表负地形——喀斯特天坑不仅是世界罕见的地质奇观,圈闭化地形而形成的独特生境更是探索植物物种多样性及其空间分布特征最为理想的地域。以云南沾益天坑群中的中度退化天坑——"巴家陷塘"坑底草地植物群落为研究对象,通过α多样性指数与β相似性系数的应用,对"巴家陷塘"中度退化天坑坑底草地植物群落物种多样性的水平空间分布特征展开探讨,并对其近邻退化漏斗和"大毛寺"原生天坑坑外草地植物群落的相似性进行对比分析,研究结果发现:(1)中度退化天坑坑底草地植物群落物种丰富度和多样性从中心到边缘呈现出"中心高边缘低"的"逆洼地效应"特征;(2)相较于土壤资源,喀斯特天坑植物群落的生长与空间分布对光照资源的响应更为明显,且四周坑壁高度差异造成的坑内光照资源的空间异质性,也使坑底草地植物物种多样性存在一定的"圈层效应";(3)喀斯特天坑独特的圈闭化地形对植物群落的"隔离"、庇护作用即使在退化天坑中也有明显体现,且对喜阴、耐湿的物种更具庇护性。因而在全球气候变化下,即使是退化天坑,也应成为区域小尺度生态避难所的重要保护对象。

Spatial distribution characteristics of grassland plant communities in a moderately degraded tiankeng in Zhanyi, Yunnan

Karst tiankengs are not only a rare geological wonder in the world with their huge negative-landform in the earth''s surface, but an ideal region to explore plant species diversity and spatial distribution, which attribute to an unique habitat formed by their trapped topography. This study analyzed the grassland plant community in the "Bajiaxiantang" karst tiankeng, which is a moderately degraded habitat in the Zhanyi tiankeng group in Yunnan Province. The alpha diversity index was applied to analyze the spatial distribution characteristics of the grassland plant community species in the bottom of this habitat, and the similarity of the grassland plant community was compared to that of the degraded doline near "Bajiaxiantang" and the outside area of the "Damaosi" primitive tiankeng using a beta similarity coefficient. The results showed that: (1) in the bottom of the moderately degraded karst tiankeng, the species richness and diversity of the grassland plant community presented an "inverse depression effect", where the species richness and diversity were higher in the center and lower at the edge; (2) compared with soil resources, the growth and spatial distribution of plant communities in the karst tiankeng were possibly more sensitive to light resources, and the spatial heterogeneity of light caused by the height difference of the tiankeng pit wall resulted in a "circle effect" of the grassland plant species diversity; (3) the isolated and protective function on plant communities by the unique trapped topography of karst tiankengs even be reflected in degraded tiankengs, and are more protective for ombrophyte. With global climate change, karst tiankengs should be served as important regional small-scale ecological sanctuaries to protect these unique ecosystems, even though they are degraded.