Community Dynamics And Shrub-grass Composition Of Pinus Massoniana Plantation In Mengguan Forest Farm,Guizhou Province

This paper takes the artificial forest of Pinus massoniana of different stand age in mengguan forest farm of Guizhou Province as the research object,this paper uses the method of space instead of time to analyze the species composition,analyzing forest stand characteristics,species of lower shrub,important values of advantage seeds,richness Index and structure of diameter class in different ages of P.massoniana with a particular,illuminating the dynamic feature of forest structure at developmental stages.It calculates associated coefficient of lower shrub community in different ages of P.massoniana with a way of variance ratio test,testing associated situations of shrubs in correlated coefficient and similar index,which reflects the associated relation and the character in different age of lower shrub.The analysis of niche’s width and overlap in different age of advantage seeds of lower shrub,which ascertains the relation of lower shrub niche.The results show that:(1)The result show that crown density declines fast in half-mature forest structure until it keep balance in mature forest structure.The average height of branch increases with its age.The most height is in half-mature forest structure.Diameter at breast height,Crown,height and Stockpile increases fast from small forest to half-mature forest,but the density declines with ages,which declines by 60% in half-mature forest.After The partition of diameter class of man-made P.massoniana,the forest structure of large sapling fores and immature timber shows a single-peak type.The forest structure of near mature forest and ripewood mature forest shows a multi-modal type.The regenerated seedling appears in the end.(2)The kinds of shrub plants contain 37 families 50 categories 51 species,including shrub of 18 families 24 categories 25 species and herb of 19 families 26 categories 26 species.The kinds of shrub show the trend of increasing initially,followed by a decline,but then increasing again with ages,whereas herbs declines with ages.The important values of the same advantaged seeds is different in different forest structure.Quercus aliena、Smilax china and Myrsine africana have obvious values and strong competition.Furthermore,Deyeuxia arundinacea and Stenoloma chusanum have obvious advantages.The index of important value of large sapling fores and immature timber Quercus aliena is 50.89% and 47.32%.The index of important value of near mature forest M.africana is 50.49%.The index of important value of ripewood mature forest Smilax chin is 50.62%.The index of important value of Dicranopteris dichotoma is in the first of all.The richness of the shrub layer increases fist,followed by a decline with the growing of forest structure.Because of the rare category of herb,the richness increases fist,followed by a decline with the growing of forest structure.The similar index of the shrub community is lower among them.The index less than 0.5 is 6pairs,equaling to 0.5 2 pairs,and the index more than 0.5 is 4 pairs.(3)The shrub community is competitive in their nearly mature period,but is not in another period.The herb community is not competitive in their young period,but is competitive in nearly mature period.The competitive pairs of herb and shrub is not obvious at large sapling forest,immature timber and near mature forest,but the competitive pairs of herb and shrub is obvious at ripewood mature forest.The situation in which the associated pairs of shrubs is calculated with three methods is same.The noncompetitive pairs are more than competitive pairs atlarge sapling forest,immature timber andnear mature forest.The pairs are competitive,but the pairs are independent totally atimmature timber.The noncompetitive pairs are more than the competitive pairs at the age of ripewood mature forest.Six pairs of herb are independent totally atimmature timber,and one is competitive totally at large sapling forest and near mature forest.The pairs of shrub appear at immature timber,near mature forest and ripewood mature forest.The noncompetitive pairs of shrub are more than herb’s.The competitive pairs of herbs are more 7 pairs than the noncompetitive pairs at immature timber.The competitive pairs of shrub are more 9 pairs than the noncompetitive pairs at ripewood mature forest.(4)The width of shrub niche declines in different stand age of forest with different method.Q.aliena and Smilax china have the widest niche and the ability of adaption and competition.The wide index of Tibet Vaccinium bracteatum and Castanea seguinii increases with their ages.The wide index of Rosa multiflora,Broussonetia papyrifera and Rubus corchorifolius declines with their ages,but their competition disappears.The niche’s width of D.dichotoma and Stenoloma chusanum is the most advantage.The competitive ability of D.dichotoma increases with its growing age,but The competitive ability of S.chusanum and Deyeuxia arundinacea increases at first,followed by a decline.The competitive ability of negative plants such as Polygonatum sibiricum,Hypolytrum nemorum declines.(5)The Species logarithm of the same niche in shrub layer declines with its growing ages.The same niche index of Q.aliena and S.chin is the most.The echo character of R.corchorifolius is similar to R.multiflora in a same way of using environmental resource.They are from different species and the same width with independent resource.The Species logarithm of the same niche in herb declines at first,followed by increasing.The marginal scaly fern overlaps S.chusanum in all ages.The species logarithm shows the echo similarity such as Q.alienalax,M.africana-C.seguinii,S.chusanum-M.marginata,D.arundinacea and Arthraxon hispidus.The species of wider niche is different from other species of overlapping niche.(6)In different development stand age of P.masson plantation,using different management measures,such as thinning and selective cutting,are used to adjust and control the stand density,provide a good growth environment for shrub and grass community and promote the development of shrub and grass community.In the ecological public welfare forest,select the native species with strong adaptability,small niche overlap and complementary ecological benefits with the existing dominant species,such as Q.aliena,S.China,D.arundinacea and D.dichotoma,are selected for configuration to improve the stability of plantation ecosystem.