| The rehabilitation and reconstruction of karst fragile eco-environment are becoming more and more difficult due to population growth, predatory use of resources and damaged to the environment in recent years, which also severely restricts the socio-economic development in karst area. Reducing the karst desertification area is one of the ways to improve the eco-environment. In accordance with the vegetation succession law, some sections, especially the severely karstification area should take some measure model of trees after grass and shrubs or tree after shrubs.The growth of shrubs in the karst environment has certain advantages. It could conserve soil and water, regulate climate better. Many of them can be used as a feed for livestock which could improve the local income because of developing animal husbandry. So, the research on fodder shrubs appears to particularly important.The nutritional value of fodder shrubs was studied in karst area integrating the comprehensive management of the southwestern karst desertification, which provides a theory for choosing suitable grass feed livestock and improving income in this paper. The distribution of elemental species in soils and leaves, different response to the eco-environment on physiological and ecological characteristics of fodder shrubs were studied in karst and non-karst area. These results would be of great significance for the development and improvement of local feed resource peak-cluster area and their ecological reconstruction.Six nutrient indices and eight elemental contents were measured and analyzed in 3 families with 19 genus and 27 species fodder shrubs. Indices are crude ash, crude protein, ether extract, crude fiber, crude ash, nitrogen free extract, glucide and full dose of carbon, nitrogen, phosphorus, kalium, calcium, ferrum, zinc, selenium. Then dates are mad grey correlative degree and correlation analysis; Species of Ca, Mg,Mn, Zn are measured in soils and leaves in karst and non-karst area, which guide improving the effectiveness of plant, soil fertility, the capacity of mineral circle and animal absorb; The content of mineral are measured in one plant in karst area, which could reveal rules of elemental distribution, accumulation and migration; The foliar carbon isotope composition (δ13C) of leaves were analyzed in karst and nonkarst area which could reveal the type of photosynthesis and plantwater use efficiency (WUE). Research materials aboutδ13C come from Mao village of Chaotian in Guilin; others come from southwestern of Guizhou.The main results are as follows:1. Assessing of 27 fodder shrubs with grey correlative degree and correlation discussion show that the excellent species are Morus mongolica (Bur.) Schneid. > Broussonetia Papyifera (Linn.) L'Hert. ex Vent. > Indigofera pseudotinctoria Matsum.> Broussonetia kazinoki Sieb.> Morus australis Poir. >Albizia calcarea Y. H. Huang> Cerasus dielsiana (Schneid.) Yüet Li. These species could be used as good feed resources for local stockbreeding. All fodder shrubs nutrimental value equivalent to leguminous shrub in Yunnan and was significantly higher than 11 Gramineae pastures in Gansu Province.2. The total contents of Ca, Mg, Mn, Zn in plants'rhizosphere soil are all generally in karst area greater than in non-karst area. The total contents of Ca and Mg in leaves are in karst area greater than in non-karst area, Mn and Zn on the contrary. The Ca and Mg have higher biological effectiveness and digestibility in karst area. Mn and Zn have higher biological effectiveness and digestibility in non-karst area.3. The nitrogen, potassium, calcium, magnesium, iron, zinc of Chimonanthus praecox were mostly distributed in leaves and it can actively absorb carbon, nitrogen, phosphorus, potassium, zinc.4. The plants have higher water use efficiency in karst area and herbaceous are significantly higher than shrubs and trees. Therefore we concluded that the response of the herbaceous physiological function to the change of the environmental factors was more sensitive and timely. |
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