| This paper dealed wtih the dry-hot valley under 1600m in Yuanmou, Yunnan province.Based on the the Landsat TM remotely sensed data in 1970, 1990 and 2000, and ivestigaion infield, the change of land use has been interpretated and mapped with the help of GIS tools suchas Arc/Info and Arcview. Then, vegetion landscape dynamics has been anylized quantatively.And the main characteristics of plant communities have been investigated through setting upsample plots. The fllowing conclusions were achieved:.(1) Dodonaea viscosa shrub and savanna shrub & grass were the landscape matrix inYuanmou dry-hot valley, accounting for 40.52ï¼…of the total areas and 25.45ï¼…of the totalpatch number. In addition to Eucalyptus camaldulensis shrub accounting for 9.63ï¼…of the totallandscape areas, the other types had less than 2ï¼…of the relative prior degree, area ratio andpatch number ratio. These landscape types included: Vitex negundo shrub, Quercus franchetiishrub, Terminalia franchetii shrub, Leucaena leucocephala shrub, Azadirachta indica shrub, Pinus kesiya Royle ex Gordon var. langbianensis shrub, Pinus yunnanensis shrub and etc. Theintroduced patch was abundant in Yuanmou hot-dry valley, and the introduced types were 50ï¼…of total types of vegetation.(2) Generally, the landscape in hot-dry valley was uneven, with low diversity andunsignificant landscape heterogeneity. The differentiation degree among vegetation types washigh, and the significant difference in patch density and edge density existed. The average sizeof patch of plantation forest was relatively bigger while its variation degree was far less thanthat of the natural vegetation landscape. Middle-size and small-size vegatation patches took upthe major part. The distribution of Dodonaea viscosa shrub and savanna shrub & grass wasdiversity and complex. The natural vegetation density and associate index were lower than theplantation forest's. The asscociation index of man-made forests was bigger than that of naturalvegetation.(3) The aera and relative priority of vegetation in research area had increased all the timeand the increase values were 35.8ï¼…and 54.7ï¼…respectively in 2000 compared with in 1970.However, the regulation function of matrix did not change, the area ratio and patch ratio of Dodonaea viscosa shrub kept above 45ï¼…and the savanna shrub & grass aslo kept 30ï¼…all thetime. The plantation forests increased rapidly, it's area ratio and patch area increased from2.38ï¼…and 4.82ï¼…to 14.21ï¼…and 20.29ï¼…respectively. During the whole research period, thepatch density of savanna shrub & grass, Dodonaea viscosa shrub, Eucalyptus camaldulensisshrub was high, which determined the heterogeneity of vegetation landscape. Theheterogeneity of Dodonaea viscosa shrub and savanna shrub & grass had the trend ofdecreasing, while the heterogeneity of plantation forest had the trend of increasing. Theheterogeneity and edge ratio of other elements did not change significantly.(4) During the whole dynamic change, the aggregation indices of all the vegetationelements were very high, especially the artificial vegetation, which belonged to the landscapeelements of human disturbance and control. Since 1970, the recently introduced vegetationpatches increased the diversity index and evenness index. Many artificial disturbances such asafforestation reduced the small vegetation patches, but increased the area and variation degreeof plantation forests. The fraction structure of vegetation patch was relatively stable, and thetotal area of the middle and small patches is the biggest. The sequence of shape index of allelements was stable during the research period, and the size of index was mainly effected bythe artificial disturbances.(5) During the study period, there were no changes in the spatial distribution of eachelement. Besides Terminalia franchetii shrub was uniform distribution all the time, the otherelements all showed aggregating distribution. The aggregation degree of Dodonaea viscosashrub and savanna shrub & grass increased while the others decreased. There was higherassociation degree between matrix and other elements among the heterogeneous vegetationlandscape in the research area. The correlation between vegetation and plantation forest wasnegative, and the association index was determined by the area of the plantation. The spatialarrangement of plantation forest patches was always adjacent and positive correlation. Thehuman disturbances such as afforestation changed the association direction and strengthamong elements.(6) The afforestation has had a profound influence on the composition, heterogeneity andspatial relationship of the vegetation landscape in Yuanmou dry-hot valley, and reduced theheterogeneity of vegetation matrix resulted in the transformation of matrix into plantation forest. The species of plantation community was simple, the species richness was low, and theplantation forest patch was lack of generalization capability, so it was difficult to konwwhether the plantation could survive. But we should pay attention to the trait that the savannashrub & grass was the rare and endangered vegetation type in our country during vegetationrestoration.
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