Study On Restoration Models Of Vegetation And Their Characteristics In Typical Karst Rocky Desertification Area

The difference of climate in Karst rocky desertification area in our country is bigger, and partial entironment is rich. The approach of restoring the Karst vegetation was various. Therefore, studying the characteristics of different models and different succession stages of vegetation restoration in the different typical Karst rocky desertification areas, and opening out the ecology rule, the physics and chemistry character of soil in different models can provide the important academic basis for combating the Karst rocky desertification.This paper mainly studies the characteristics of different stages of hill closing for forest, dendrocalamus latiflorus forest, bamboo-deciduous forest, zenia insignis forest, choerospondias axillary forest and agroforest model in Lingyun County Guangxi Zhuang Autonomous Region. Studies the characteristics of different stages of hill closing for forest, plum forest, cupressus duclouxiana forest and agroforest model in Puding County Guizhou Province. And studies the characteristics of different stages of hill closing for forest, armand pine forest and pine-deciduous forest in Fuyuan County Yunnan Province. Main conclusion as follows:(1) In the last succession stage of hill closing for forest, the plant in different layers is neuter and forbearing shade species. But the difference of species composition in different stages in the three studying place is bigger. There are mainly evergreen broad-leaved trees when entering the stage of arbor-shrub in the west Guangxi area. There are not only evergreen species but also defoliating species in this stage in central Guizhou Province. But there are mainly evergreen species in this stage in east Yunnan Province. The plant species in tree layer is humdrum in human forest, and the plant species in herbosa and shrub layers was effected by jamming.(2) The changing tendency of diversity in different layers of hill closing for forest was not consistent in three typical Karst rocky desertification areas. It has respective succession rule in every area. The diversity in herbosa layer was the most in the stage of herbosa of hill closing for forest in west Guangxi, then declined gradually. This diversity index changed unconspicuously from the stage of herbosa-shrub to arbor-shrub, but declined obviously to the last succession stage in this area. In central Guizhou, the diversity in herbosa layer raised firstly, then declined. The species richness was the most in the stage of herbosa-shrub, but simpson and shannon index was the most in that of vine-shrub. The diversity index in herbosa layer changed undeely. In west Guangxi and central Guizhou, the diversity index in shrub, arbo layer and community raised firstly and reached the most in the stage of arbo-shrub, then declined. In east Yunnan, the diversity index in shrub and arbo layer changed undeely, and that in the community raised firstly and reached the most, then declined, but the time when the index reached the most was not consistent.At the beginning of hill closing for forest, the diversity in herbosa layer was greater than that in shrub layer .Then the diversity in shrub raised and exceeded that in herbosa layer finally, but the stage when that appeared was not consistent. It was in the stage of vine-shrub in west Guangxi, in the stage of arbo-shrub in central Guizhou and east Yunnan. When arbo appeared, the diversity in shrub layer was the greatest, and that in arbo layer was the least.(3) In central Guizhou, the diversity of plum forest was affected by human disturbance largely. The diversity of every layer and community was the least in beginning fruit stage. when developed after the abundant fruit stage, it raised. It reached the most in declined stage. The diversity in herbosa layer of cupressus duclouxiana forest raised from herbosa layer, and reached the most to beginning lignum stage. That in shrub was the least in beginning lignum stage. That of community declined gradually as succession. In east Yunnan, the diversity of armand pine forest in every layer and community raised as succession and reached the most in the beginning lignum stage, then declined gradualy. That in shrub layer and community reached the least in ripe lignum stage. Compared with defoliate- latifoliate forest, the diversity of dendrocalamus latiflorus forest is lower. The diversity in arbo layer and community of bamboo- latifoliate forest can be improved, but that in herbosa and shrub layer was restrained.(4) The effect that hill closing for forest could improve the species diversity was the best, while the lignum forest was the worst. At the beginning of vegetation succession, the species composition and diversity was determined by the land utilization way. The plant species in droping out farmland was primaryly the one year growth herbosa and the diversity of it is high. The plant species in afforestation in the wild is perennial herbosa, preponderant species was obvious, and the diversity was worse. In metaphase stage, the difference of species diversity of all models came out. The diversity of hill closing for forest was the hightest in all models from metaphase stage to the last succession stage. The diversity in shrub layer and community of lignum forest was higher than that of fruit tree forest, while it was contrary in herbosa. The diversity of agroforest model was the lowest in all models. In the last stage, the diversity in all layers and community of lignum forest declined, and it became the model that the diversity is the lowest. That of fruit tree forest raised, and it became the human forest model that the diversity was the highest.(5) Hill closing for forest could improve the physical and chemic characteristics of soil obviously. At the beginning of hill closing for forest, soil hardened in a short-term. After the herbosa-shrub stage, the physical character improved, the volume weight decreased and the air permeability increased gradualy. In the process of vegetation succession, the soil pH value reduced unceasingly, and the soil became alkalescence from acidic except east Yunnan. The quantity of OM and N in soil was the lowest in herbosa-shrub stage, then increased. That in west Guangxi and east Yunnan achieved the highest in the last stage of succession, but that in central Guizhou achieved the highest in arbo-shrub stage. In the vegetation succession, the quantity of P and K had different rule of movement. The quantity of P in soil in west Guangxi decreased from the beginning to metaphase stage fleetly, then rebounded little. The quantity of available K changed little, but the quantity of total K decreased ceaselessly in forepart, and became steady in metaphase. In central Guizhou, the quantity of P was the least in herbosa-shrub stage, then increased gradualy. The available K increased ceaselessly in the whole course of succession, but that of total K was contrary. In east Yunnan, the quantity of P and available K was the least in herbosa-shrub stage, then increased gradualy. The total K fluctuated greatly. The quantity of OM and N moved conformably in the three experimental point, but the rule of movement about the quantity of P and K was different obviously.(6) The model of plum forest can not improve the volume weight and air permeability. The soil became acidic from alkalescence in the course of plum growth. The plum required large numbers of OM, N and P from the stage of springwood to rich fruit forest, while the requirement decreased after the recessionary stage. In the whole course of growth, the plum require litter K. So, the K in soil got together ceaselessly. The cumulation of Ca, Mg and Fe in soil was greater than loss.The volume weight and air permeability in soil in cupressus duclouxiana forest did not change before the stage of beginning lignum. Then the volume weight decreased and air permeability increased. The same as hill closing for forest, the soil in cupressus duclouxiana forest became alkalescence from acidic and the air porosity rised. Before the stage of beginning lignum, the growth of cupressus duclouxiana required large numbers of OM, N and P .Then, the cumulation was greater than expenditure. the growth of cupressus duclouxiana required liter K, so it cumulated ceaselessly. The loss of Ca and Mg is great.The armand pinus forest can not improve the physical and chemic character of soil obviously. The volume weight was the least, and the air permeability, quantity of OM and N was the most. Then, the soil hardened more. The quantity of OM and N decreased gradualy because of not supplement. The quantity of P and K cumulated, because it was consumed few. The quantity of Ca and Mg was the most in the stage of ripe forest.In the Karst area in west Guangxi, the physical and chemic character of soil in defoliating-latifoliate forest was the best, agroforest took second place, while that in dendrocalamus latiflorus was the best. Bamboo- latifoliate forest could improve the character of soil, but it was not as good as defoliating- latifoliate forest.