Study On Quantitative Ecology Of Juglans Mandshurica Communities In Lishan Mountain, Shanxi

Lishan mountain,belonging to Zhongtiao Ranges,is situated in 111°51'10''～112°05' 35" E,35°16'30"～35°27' 20" N in the southeast Shanxi.It has a typical warm-temperate continental climate with abundant plant resources and higher biodiversity.As an endemic to China,Juglans mandshurica is ranked one of the national third-class and Shanxi provincial first-class protection of rare and endangered plants.Due to its multiple economic values,distribution area and population number is shrinking and seriously influenced by human activities.Based on the investigation in Lishan Mountain,J.mandshurica community characteristics were studied systematically and comprehensively by using quantitative ecology methods,including community classification and ordination,species diversity and interspecific segregation etc.The aims of this study were to present some theoretical basis so as to protect this endangered species from damage,recover population and utilize sustainable for the resource.The ecological relationship between J.mandshurica communities and environment was analyzed by using TWINSPAN and DCA.The results were as following:J.mandshurica communities were classified into 7 types by TWINSPAN,and the main factors that restricted community distribution were aspect and terrain.The results of DCA ordination indicated that the main factors that restricted community distribution were aspect,terrain,and soil type.The first of the DCA ordination axes indicated the aspect gradient, and the second of that indicated the terrain and soil type gradient including soil thickness,soil humidity and organic content.The ordination of species and quadrats showed that the ordination of the dominant species in the communities was similar to that of the community types,and to some extent, the distribution pattern of the dominant species determined that of the community type.The relationships between species diversity and community types, community structure,environmental factors were studied by using the richness indices,diversity indices and evenness indices.The results showed that:There are difference of richness indices,diversity indices and evenness indices among seven associations.The main factors were physical micro-environmental factors such as aspect,slope,soil type etc.and communities constituent,communities structure as well as disturbance of human activities.The analysis of variance showed that the differences of richness indices,diversity indices and evenness indices were not significant among associations.Also the differences of those of arborous layer,shrub layer and herb layer in each association were not significant.These indicated that the habitat of J.mandshurica communities was not greatly heterogeneous,and the species in the communities have the similar adapting characteristics to the regional climate and the similar way utilizing the resources.The interspecific segregation for all trees and shrubs in the J. mandshurica communities was studied by using Pielou's segregation index,χ~2-test,an N×N nearest-neighbor contingency table and a 2×2 nearest-neighbor contingency sub-table.The result ofχ~2 showed that there were 294 species-pairs being significant segregation(p＜0.05) and 6 species-pairs being insignificant segregation(p＞0.05).Based onχ~2 value to divide S,the interspecific segregation results indicated that positive segregation,negative segregation and random segregation accounted for 37.34%,9.33%and 53.33%respectively.Negative segregation appeared between dominant species and companioning species in the communities and companioning species had fewer individuals,lower coverage and similar habitat requirements with dominant species.Intensive interspecific competition resulted in mosaic distribution and fully exploiting competition for resources in species.The larger individuals being constructive or dominant species in the communities tended to be positive segregation with other trees and shrubs,due to their stronger capacity of adaptation and competition.The constellation diagrams showed clearly the difference of interspecific segregation among the various species.In addition,the results of interspecific segregation suggested that the J.mandshurica communities in Lishan Mountain were in the early unstable stage of succession.