Influences Of Environment And Competition On DBH Growth With Different Growth Stages In A Typical Mixed Broadleaved-Korean Pine Forest,Northeast China

Recently,the influencing mechanism of environment and competition on tree growth is getting more attentions.The research was conducted in a 9 ha mixed broadleaved-Korean pine?Pinus koraiensis?forest dynamic plot in Liangshui,Heilongjiang Province,China.Based on field investigation data in 2010 and 2015,this study analyzed the influences of topography?i.e.,aspect,gradient,topographic position?soil(bulk density(g cm^-3),total N(mg g^-1),available N(mg g^-1),total P(mg g^-1),available P(mg g^-1),organic C(g kg^-1),soil pH,volumetric water content(cm³ cm^-3))and competition of trees on the increment of diameter at breast height?DBH?for major tree species in mixed broadleaved-Korean pine forest.Results showed that the annual average DBH increment of saplings?1 cm?DBH<10 cm?for Tilia amurensis,Acer mono and Abies nephrolepisas well as large trees?DBH?10 cm?for Pinus koraiensis,Tilia amurensis,Acer mono,Fraxinus mandshurica were all significantly correlated with the topography?P<0.05?.The annual average DBH increment of Fraxinus mandshurica,Betula costata,Ulmus japonica and Acer tegmentosum for saplings was all significantly correlated with the soil?P<0.05?.The annual average DBH increment of Pinus koraiensis,Tilia amurensis,Acer mono,Fraxinus mandshurica Abies nephrolepisas Ulmus japonica and Acer tegmentosum for large trees was all significantly correlated with the soil?P<0.05?.The competition had significant influences on the annual average DBH increment of Pinus koraiensis,Tilia amurensis,Acer mono,Fraxinus mandshurica,Abies nephrolepis,Betula costata,Acer tegmentosum for saplings as well as large trees for Pinus koraiensis,Tilia amurensis,Acer mono,Ulmus japonica?P<0.05?.Generally,the annual average DBH increment of shade-tolerant and non shade-tolerant groups was significantly influenced by topography,soil and competition in mixed broadleaved-Korean pine forest.The DBH increment of large trees of trees was mainly influenced by the topography,while the DBH increment of saplings of trees was mainly influenced by the competition.The soil had significant influences on the annual average DBH increment of the different life stages of trees in mixed broadleaved-Korean pine forest and the same soil factor had different influences on the annual average DBH increment of trees at different life stages,and even the opposite.The transformation and cycling of nitrogen was the important and active process in mixed broadleaved-Korean pine forest,and there was habitat filtering from saplings to large trees.The process of habitat filtering contributed to ontogenetic variation that control RGR and MR as community transition from saplings to large trees.Moreover,water availability played a key role in this process in the mixed broadleaved-Korean pine forest.