The Stady On The Soil Mini-area Characters Of Steppe In The West Of Jilin Province And The Copling Relationship Between The Soil And Vegetation

The abundant grassland resources provide stable substance base for the plan of constructing a strong grassy graze province in Jilin. At present, the traditional grassy graze area contained about 90% of exploitive grassland resources in the west of Jilin. Because of the long irrational exploiture, the area of the degenerating had accounted for 42%-64% of the grassland. Entironmental degenerating had badly restricted the development of local social economy .So the study on improvement of the degenerating and salinizating grassland had became an important node of the sustainable development of technique and economy in the west of Jiniin.In the ecosystem of grassland, the degeneration and salinization of grassland was an unitary retrogressive succession, but their restoration was an progressive succession when exterior disturbance is weakened or stopped. Whether the succession is retrogressive or is progressive, they changed in the system, such as cycle of materials, energy flow, and ability and mode responsing to the outside factors, especially vegetation of grassland , soil environmental factor and theirs relationship . For opening up the character, mechanism of the changes of grassland vegetation and physical and chemical characters of soil and relationship between them in the mini-area, this paper discussed the characters of grassland vegetation and soil and soil-grass coupling in grazing degenerative grassland in the west (Qianguo area)of Jilin, with the methods of regression analysis and grey system analysis.1. On the level of mini-area, the order of salinization extent was Bare land>Suaeda corniculata com. ( com.is logogram of community)>Puccinellia tenuiflor com. > Carex duriuscula com. Phragmites communis com. > Leymus chinensis com. >Bolboschoenus compactus com.>Ranuculus cymbalaria com. >Potentilla anserine com.. The salinization degree of Bare land, Suaeda corniculata com., Puccinellia tenuiflor com., Carex duriuscula com. and Leymus chinensis com. had the same trend with the vegetation secondary salinized succession. Soil water content was lowest in Bare land., and noterrophyte and xerophile community was lower than hygrophyte community.2. The soil nutrition content in Carex duriuscula com., Phragmites communis com.,Leymus chinensis com.and Ranuculus cymbalaria com.was higher than other communities . And soil nutrition content in every sampling spot had not the same current and the succession of salinization and solonization in the commmuity.3. Most of cations are Na⁺, most of anions are CO₃^2- and HCO₃^-. In addition the cationscontained a bit of Ca2+ and Mg2+, and the anions contained Cl'and SO42", too. The soda content had the same trent with soil solonization .4. The Bare land, Suaeda corniculata com. and Puccinellia tenuijlor com. was soda meadow solonetz. The others were all salinization soda meadow soil. In which the Carex duriuscula com., Phragmites communis com., Leymus chinensis com.and Bolboschoenus compactus com soil was intermediate salinization, and in Ranuculus cymbalaria com. and Potentilla anserine com. was mild salinization, 05. In the division of the soil texture, Puccinellia tenuijlor com.and Carex duriuscula com.belong to silty clay, Leymus chinensis com.and Bolboschoenus compactus com belong to sandy silty clay, Bare land, Suaeda corniculata com., Phragmites communis com., Ranuculus cymbalaria com.and Potentilla anserine com.belong to sandy silty clay0 The soil structure of Leymus cinensis com. was reasonable relatively, while the Bare land and Suaeda corniculata com.were not reasonable. The diameters of soil microaggregate were largely between 0.01mm and 0.25mm. in every sampling spot. The extent of soil dispersion increased with the soil secondary succession gradually.6. The sequence of CV of the physical and chemical index in the sampling spot is SoilpH>Soluble salt content> Conductance> Alkalinity> Available P> Organic >Total N> Hydrolyzable N>Soil water content> Available K>Total P.7. Underground root biomasses of four communities had the drop current with the soil depth downward. The gross of root biomass were the biggest in Leymus chinensis com., secondly were in leymus-Inulla com. and were the smallest in over-grazing grassland. The indexes, which indicated the salinization degree of soil had the rising current with the soil depth downward. According to the degree of salinization, the frequency of the four communities was Over-grazing grassland >Leymus-Puccinellia com.>leymus-Inulla com.>Leymus chinensis com.. The indexes, which indicated the nature of soil nutrition had the dropping current with the soil depth downward, and the difference berween the four communities were not significantly.8. The result of grey system analysis showed that the grey correlative degree between Available K, Available P, Hydrolyzable N, organic and the underground root biomass of community were big. Furthermore the degree of the grey correlative had the same trend with the underground root biomass, which was the dominant factor. The grey correlative degree between pH, ESP, Conductance, Salt content and the underground root biomasswere small, which had the negative trend with water content and underground root biomass was nether restrained significantly nor dominant factor, which was in the middle of the formers.9. The result showed that the fitness extent of soil-grass coupling was Leymus chinensis >leymus-Inulla com. >Leymus-Puccinellia com. com. >Over-grazing grassland in the four communities. The process of restoration succession on Over-grazing grasslan also occurred when the fitness of soil-grass coupling was improved dramatically.