The Study On Community Diversity And Niche Characteristics Of Plantation In Loess Alpine Region

Forestry ecological engineering can’t reach the goal because of differences in plant environment adaptability and complex topography in Loess Alpine Region.The study on the ecological characteristics of plantation community under different site conditions is needed to improve the quality of plantation.It is expected that the study results help the ecological restoration in Loess Alpine Region.The study object is the plantation community in the Datong County Anmentan Watershed.The research content is the ecological characteristics and change rules of plantation communities by using the methods of field investigation and indoor data analysis,with calculating species diversity index,niche breadth and niche overlap.The results are summarized as follows:(1)The site conditions are divided into shallow shady flat slope,shallow shady gentle slope,shallow shady steep slope,shallow sunny flat slope and shallow sunny gentle slope.The community structure of plantation is dominated by arbor and herb.Plantation community is mainly composed of monotypic genera,lacking medium and large genera.(2).Site conditions type had no significant effect on species diversity of arbor layer(P>0.05).Site conditions type had significant effects on Margalef richness index of herb layer(P<0.05),but had no significant effects on Pielou evenness index,Shannon-Wiener diversity index and Simpson dominance index(P>0.05).The bigger the slope,the better the development of species richness and diversity in herb layer according to the order of species richness index and diversity index.(3).The niche breadth of tree species ranges from 0.1 to 0.4 and from 0.01 to 0.60 respectively on the shallow shady flat slope and shallow shady gentle slope.The value of Picea crassifolia is the largest with the strongest ability of resource utilization.The niche breadth of tree species ranges from 0.2 to 0.8 on the shallow shady steep slope.The value of Populus cathayana is the largest with the strongest ability of resource utilization.The niche breadth of tree species ranges fror 0.1 to 0.4 and from 0.2 to 0.6 respectively on the shallow sunny flat slope and shallow sunny gentle slope.The value of Sabina przewalskii is the largest with the strongest ability of resource utilization.The average niche breadth of herb species ranges from 0.1 to 0.2 on the different site types.The herb communities have the strongest ability of resource utilization in the shallow shady gentle slope.(4).The average niche overlap values of tree species range from 0 to 0.1 on the shallow shady flat slope,shallow shady gentle slope,shallow sunny flat slope and shallow sunny gentle slope.The value is relatively small and the interspecific competitive pressure is low,and that is 0.411 on the shallow shady steep slope.The value is higher and the interspecific competitive pressure is relatively high.The average niche overlap values of tree species range from 0.1 to 0.3.The competition pressure between herb species gradually decreased with the increase of slope.