摘要:喀斯特退化天坑倒石坡作为一种负地形坡面，在退化天坑植物避难所的物种多样性保护中发挥着重要作用。研究坡面土壤微生物群落功能多样性，有助于阐明土壤微生物群落生态特征和空间分布规律，探索土壤微生物与植物多样性关联，挖掘退化天坑负地形倒石坡的生物多样性宝库价值。研究以云南沾益天坑群中的退化天坑-巴家陷塘为研究对象，运用Biolog微平板技术，分析坡面环境梯度（坑口﹑上坡位﹑中坡位﹑下坡位以及坑底）的土壤微生物群落功能多样性差异。结果显示，坑底土壤微生物群落的功能多样性指数（Shannon指数﹑Simpson指数﹑McIntosh指数）、碳源利用程度均显著高于坑口。下坡位的土壤微生物群落功能多样性略高于坑底，显著高于中坡位，呈现出下坡位 > 中坡位 > 上坡位的趋势。坡面土壤微生物群落主要利用的碳源为糖类和氨基酸类。2个主成分分别解释所有方差变量的31.9%和28.7%，能区分不同坡位土壤微生物群落的碳源利用。坑内外草本植物α多样性指数差异显著，坑坡木本层植物α多样性指数差异显著（P < 0.05），其中下坡位木本层植物多样性最高。β多样性指数显示不同坡位的生境具有差异性，但下坡位生境类型最多样。研究发现，喀斯特退化天坑倒石坡的独特负地形和土壤环境孕育了较高的植物多样性和土壤微生物群落功能多样性，二者的空间分布较为一致，未来在退化天坑物种多样性保护中应特别注意倒石坡地下森林资源价值。



Abstract:The negative topographic slopes in a degraded karst tiankeng play an important role in protecting plant diversity. Studying the functional diversity of soil microbial communities on slopes aids in clarifying the ecological characteristics and spatial distribution of soil, to explore the relationship between soil microorganisms and plant diversity, and to assess the biodiversity of degraded karst tiankengs. The degraded tiankeng "Bajiaxiantang" of Zhanyi county in Yunnan Province was selected as the study site. A Biolog MicroPlate was used to analyze the functional diversity of the soil microbial community in the slope environment and how soil microbial community functional diversity varied with gradient (pit, uphill, mid-slope, downhill, and pit bottom). The results showed that the functional diversity indices (Shannon, Simpson, and McIntosh) and the carbon source utilization degree of the soil microbial communities at the pit bottom were slightly higher than those at the pit level and were significantly higher than those at the mid-slope level, showing a trend of downhill > mid-slope > uphill. The main sources of carbon used by soil microbial community on slope are sugars and amino acids.. The two principal components account for 31.9% and 28.7% of all variance and can distinguish the carbon source utilization of soil microbial communities in different slope positions. The α diversity index of herbaceous plants inside and outside the pit was significantly different. The diversity index of woody plants on the slope was significantly different (P < 0.05), and the diversity index of the woody plants was highest downhill. The β diversity index showed that the habitats of the different slopes are different and that the habitats of the downhill area are the most diverse. The study found that the unique negative topography and soil environment of the degraded karst tiankeng talus slopes led to to higher plant diversity and higher functional diversity of soil microbial communities, and that the spatial distribution of the two is consistent. Thus, special attention should be paid to the value of underground forest resources on the talus slopes.





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