滇西北与滇东南干热河谷植物群落物种多样性研究

环境变迁下生物多样性格局形成及维持机制研究是生物多样性研究的核心科学问题之一. 滇西北和滇东南两地曾在地质历史上具有相似森林植被，随着板块运移，两地出现明显环境区化，植被类型亦产生巨大变化，仅在两地干热河谷生长着相似外貌和类型的植物群落，而其物种组成和生物多样性格局有何异同尚不清晰. 该研究分别在怒江和元江干热河谷设置100 km样带，每间隔4 km布设样地，对其植被进行群落学调查. 通过计算两地不同生活型植物重要值、Alpha及Beta多样性指标，拟阐明起源相近、外貌相似的两地植被在环境变迁后群落物种组成及生物多样性的变化规律. 结果表明:①滇西北干热河谷共调查到维管植物125种(51科104属)，滇东南干热河谷共调查到114种维管植物(44科102属). 滇西北乔木和灌木物种丰富度均略高于滇东南，草本反之. 滇西北乔木多度极显著高于滇东南(P<0.01)，灌木多度未出现显著性差异，草本多度滇东南显著高于滇西北(P<0.05). ②从科水平分析，滇西北和滇东南乔木和草本优势科组成种类相似，但灌木优势科组成种类差异性较大. 从种水平分析发现，两地乔木优势种种类差异较大，而灌木和草本组成相似. ③滇西北植物群落Shannon-Wiener指数、Simpson指数均略低于滇东南，但无显著性差异，而Pielou指数显著低于滇东南(P<0.05). 滇西北干热河谷植物群落中优势种单一，物种分布具有聚集性；滇东南植物群落物种分布较均匀，物种多样性丰富. ④两地植物群落之间相异性系数较高，处于极不相似水平，群落间生境差异性较大，不同生活型植物Beta多样性差异极显著(P<0.001)，其中以灌木物种组成的相异性最大. 研究显示，起源相近、外貌相似的滇西北与滇东南干热河谷的植物群落物种组成存在明显差异，Alpha多样性差异不明显，Beta多样性存在显著性差异，环境变迁后区域环境差异改变了植物群落结构. 

Study on Species Diversity of Plant Communities in Dry-Hot Valleys of Northwest and Southeast Yunnan

The formation and maintenance mechanism of biodiversity pattern under environmental change is one of the core scientific issues of biodiversity research. Northwest Yunnan and southeast Yunnan had similar forest vegetation in geological history. With the movement of the plate, the two places have obvious environmental regionalization, and the vegetation types have also changed greatly. Only in the dry-hot valleys of the two places, similar appearance and vegetation have been developed. The similarities and differences in their species composition and biodiversity patterns are unclear. In this study, 100 km transects were set up in the dry-hot valleys of the Nujiang River in northwest Yunnan and the Yuanjiang River in southeast Yunnan. The sample plots were set up at intervals of 4 km, and the vegetation community survey was carried out. By calculating the important values, Alpha and Beta diversity indicators of different life-type species in the two places, it is proposed to elucidate the change law of community species composition and biodiversity after environmental changes in the dry-hot valley vegetation of the two places with similar origins and similar appearances. The results showed that: (1) A total of 125 species of vascular plants, belonging to 104 genera in 51 families, were recorded in northwest Yunnan, and 114 species of vascular plants, belonging to 102 genera in 44 families, were recorded in southeast Yunnan. The species richness of trees and shrubs in northwest Yunnan was slightly higher than that in southeast Yunnan, and the opposite was true for herbs. The tree abundance in northwest Yunnan was significantly higher than that in southeast Yunnan (P<0.01), while the abundance of herbs in southeastern Yunnan was significantly higher than that in northwestern Yunnan (P<0.05). There was no significant difference in shrub abundance. (2) At the family level, the species of the dominant family of trees and herbs were similar, but the dominant families of shrubs were quite different. However, at the species level, the dominant species of trees differed greatly, while the composition of shrubs and herbs was similar. (3) The Shannon-Wiener index and Simpson index of plant communities in northwest Yunnan were slightly lower than those in southeast Yunnan, but there was no significant difference. The Pielou evenness index in northwest Yunnan was significantly lower than that in southeast Yunnan (P<0.05). The dominant species in the plant community in northwest Yunnan was single, and the species distribution was clustered. In contrast, the plant community in southeast Yunnan was more evenly distributed and rich in species diversity. (4) The coefficient of dissimilarity between the plant communities in the two places was relatively high, at a very dissimilar level. The differences of habitats between the two communities were great, and Beta diversity of different life forms was extremely different (P<0.001). Among them, the shrub layer had the greatest dissimilarity. The research shows that the plant communities in the dry-hot valleys of northwest Yunnan and southeast Yunnan with similar appearance and origin were significantly different in species composition, and different life forms were different. Alpha diversity of plant communities in the two places was not significantly different, but there was a significant difference in Beta diversity. After environmental changes, regional environmental differences changed the structure of plant communities.