Study On Construction Dynamic Traits Of Hill-closed And Afforested Pinus Tabulaeformis Community In Huanglong Moutains

Six traits of Pinus tabulaeformis community,including construction of system,growth characteristics,niche, association of plant species,bio-diversity and soil traitsof forestland in series of hill-closed and afforestation (HCA)ages in HuanglongMountains were studied. The findings show as following. 1.In Pinus tabulaeformis community, the main plant species belongs toAsteraceae,Gramineae,Papilionaceae,Rosaceae,Violaceae et.al. and speciesdistributing to the North Temperate Zone are most. Before HCA 45 years,the longerHCA ages,the more species abundance. After HCA 45 years,except dominativespecies in tree layer, the dominant species in shrub and herb layers is not apparent.The order of biodiversity indexes is shrub layer>tree layer>herb layer. 2.The dominant height and DBH(diameter breast height)of Pinus tabulaeformisindividuals distribute to 2～4m ＆ 6～8m,and 0～2cm ＆ above 20cm,respectively. The average density of plants is 13.20／100m2 and 386.99／100m2 intree layer and shrub one,respectively. Big and middle class density occupiesdominance in tree layer and small class in shrub layer. If HCA age is longger,middleand small density will occupy dominance in tree and shrub layer,respectively.InPinus tabulaeformis population,middle and small trees are more,big ones are less andits age construction type belongs to evolutional type. 3. The niche width order of main population is Pinus tabulaeformis>QuercusLiaotungensis> Syringa oblate,Lespedeza dahurica>Rubus corchorifolius>Spiraeafrischiana var .angulata, Bothriochloa ischaemum>Spodiopogon sibiricus>Kengiaserotina. The more niche overlap values of species pairs are Pinus tabulaeformis andSyringa oblate,Pinus tabulaeformis and Quercus Liaotungensis,Lespedeza dahuricaand Rubus corchorifolius,Lespedeza dahurica and Spiraea frischiana var .angulata,Lespedeza dahurica and Acer ginnala,Bothriochloa ischaemum and Spodiopogonsibiricus,Bothriochloa ischaemum and Kengia serotina. In sequence of HCA in Pinustabulaeformis community,the whole association of main species is positivelycorrelation. Association of Pinus tabulaeformis and other trees,Syringa oblata andPrunus davidiana,Prunus davidiana and Xanthoceras sorbifolia is mighty positivecorrelation. With HCA ages increase,comparability coefficient of species decreases.Among HCA ages 16yand 25y,60y and 75y,comparability coefficient of species inPinus tabulaeformis community is more. 4. In the same HAC age,with sampling depth increase ,soil organic matter(SOM)decreases. Before and after 30 years in sequence of HAC,with HAC age increase,SOM increases and decreases,respectively. Before HAC 16 years and after 45 years,with HAC ages increase,bulk density of soil in surface totally increases. Among HACages 30years to 45 years, with HAC ages increase,bulk density of soil in surfacedecreases.In sequence of HAC ,with sampling depth and HAC ages increase ,pH ofsoil totally increases.The scale of soil pH in forest land in research zone is 8.2～8.6.In the same HAC ages,with sampling depth increase ,NO-3-N,NH+4-N and availablenitrogen totally decrease. In the same sampling depth , NO-3-N increase anddecrease,before and after HAC 30 years, respectively. In sequence of HAC, NH+4-Nhas not apparent trend but available phosphor(AP ),available potassium(AK) andurease of soil in surface layer is more and CAT is less than in undersurface layers. Thescale of AP is 3.5mg/kg ～8.5mg/kg. With HAC increase,AK of soil in 20cm～40cmand 40cm～60cm totally increases. With sampling depth increase,urease decreases.With HAC ages and sampling depth increase,CAT of soil increases. With HAC agesincrease,comprehensive factor value of soil decreases.