Different Vegetation Types Community Structure And Soil N7utrient In Loess Hilly And Gully Region

The common vegetation types of returning farmland to forest were studyed as the objectin loess Hilly and Gully Region. Based on field observation and laboratory experiment,species diversity characteristics, soil organic matter, total nitrogen were measured andcalculated. Results showed that there is the relationship between the vegetation restorationand soil nutrient. It provides proper evaluation of vegetation restoration effectcts in LoessHilly Region. The main research results were summarized as follows:(1)Community characteristics and composition of Families, genera and species weredifferent among the different vegetation restoration types, and species constitute presented asmost species belonging to a small number of families, The major plants were concentrated inRosaceae, Compositae and Leguminosae, Therefore, the three families play an important rolein the community of this area.(2)The community diversity varied evidently with different restoration years. ForR.pseudoacacia community, the order of Richness index, Simpson index and Shannon-Wienerindex was35a R.pseudoacacia>45a R.pseudoacacia>20a R.pseudoacacia,and the order ofSheldon evenness index was45a R.pseudoacacia>35a R.pseudoacacia>20a R.pseudoacacia;For Caragana microphylla Community, the order of Richness index and Shannon-Wienerindex was40a Caragana microphylla Community>30a Caragana microphyllaCommunity>15a Caragana microphylla Community, and the order of Simpson index andSheldon evenness index was40a Caragana microphylla Community>15a Caraganamicrophylla Community>30a Caragana microphylla Community; For abandond landcommunity, the order of Richness index and Simpson index was5a abandond land>3aabandond land>1a abandond land, and the order of Sheldon evenness index andShannon-Wiener index was3a abandond land>5a abandond land>1a abandond land.(3)Soil nutrient was different among the different vegetation restoration types.In verticaldirection, nutrient accumulation effect has the table; Nutrient was different in the Communityof the same type, which increased with with restoration year increased;Correlation analysisbetween the indexes of soil nutrients proved that the organic matter is the source of soilnutrients. However, these types of nutrients in the whole area are at a low level. (4)The significant correlations between species diversity and soil nutrient indicated thatsoil organic matter and total nitrogen are the key factors that influencing the plant communitycomposition and diversity.