云南省元谋干热河谷的第四纪植被演化

元谋干热河谷植被呈多顶极分布格局．稀树灌草丛是一具次生性的河谷气候顶极群落，但在发生上也有一定的古老性．扭黄茅＋车桑子群落是在现代自然－人为因素强烈影响下形成的一个亚顶极群落．

VEGETATION EVOLUTION IN YUANMOU DRY-HOT VALLEY SINCE QUATERNARY PERIOD

The vegetation evolution in Yuanmou Dry-Hot Valley since Quaternary Period was studiedby using lots of the paleontologic fossils, paleogeographic, paleo-environmental informations,recorded history and field information personally to be surveyed.The results show: In early period of the evolution---before the New Stone Age, the vegetation evolution was mainly controlled by the zonal climate and the dry-hot climate that was formed with the valley's formation. In the Early Pleistocene,the vegetation types consist of the evergreen broad-leaved forests with the elements of the tropical and subtropical rain forests, mountainsclerophyllous oak forest and aquatic vegetation. In the Middle and Late Pleistocene, the vegetation types include the valley-sclerophyllous oak forest, the mixed sclerophyllous oak forest of valley and mountain,woodland and herb swamp,woody swamp. Prom the Holocene to New Stone Age, mainly having the typical valley-sclerophyllous oak forest,savanna (similar to savanna), but likely there should be community fragments before then,and with basinning the original farming in valley basin. In the late Period of the evolution (400-500a BP), the vegetation evolution was controlled by the further reinforced dry-hot climate,parhcally the interactions were brought about by the human activities, the frequent hill-fire and serious soil erosion etc. The community fragments of the existing valley-sclerophyllous oak forest and savanna have bigger difference from the original communities. The community of Heteropogonetalia contorti Dodonaeo angustifolia is a more stable secondary community. On the extremely dry-hot shine-slope, there was the fleshy-thorny scrub.On the basis of the above, the distributions of the vegetation types in Yuanmou Dry-HotValley behave the polyciimax pattern.