Community Structure And Dynamics Of A Typical Mixed Brodleaved-Korean Pine(Pinus Koraiensis) Forest

The mixed broadleaved-Korean pine (Pinus koraiensis) forest (MBKF) is the climax vegetation type of eastern mountain areas in northeastern China. Due to regional variations, both community characteristics and species composition of Korean pine forest varied a lot. Basically, the Korean pine forest could be divided into three categories of southern MBKF, typical MBKF and northern MBKF. Following the field protocol of the50hm2plot in Panama (Barro Colorado Island, BCI), a9hm2MBKF permanent plot was established in2005in Liangshui National Nature Reserve of Heilongjiang province. All free-standing individuals with DBH (diameter at breast height)≥1cm were mapped, tagged and identified to species in the plot. In the2010census, we had documented48woody species with21355individuals (including34021sub-branches), belonging to20families and34genera. Most of the species belong to Changbai Mountain plant flora, Xiaoxing’an Mountains plant subline with inclusion of some subtropical species. DBH distribution of all individuals showed a reversed "J" type, indicating good regeneration across the community. DBH distribution of four forest layers showed two types:1) the reversed "J" distribution (canopy layer, subcanopy layer and middle layer), and2)"L" distribution (understory layer). DBH distribution of the dominant species can be classified into three categories:1) approximate normal distribution,2) reversed "J" distribution, and3)"L" distribution. Spatial distributions of major tree species were aggregated, and for most species, the extent of aggregation decreases as increases of the DBH class. The species distribution is closely related to topography and varied with DBH classes. The distribution of Pinus koraiensis and Tilia amurensis was significantly affected by topography (P<0.05). However, the distribution of Abies nephrolepis, Acer ukurunduense, and Ulmus laciniata showed significant correlation with topography at diameter class Ⅰ (DBH<10cm) and diameter class Ⅱ(10cm≤DBH≤30cm), and the distribution of Betula costata and Acer tegmentosum showed significantly correlation with topography at diameter class Ⅰ (P<0.05). The impact of topographic gradient on the species distribution decreased significantly as increases of the DBH class. Based on data from one census in2005and2010, the number of species has not changed. A total of4433stems were recruitment and2715died during five years. The mean DBH of2005(9.95cm) stems>2010(9.29cm) and the basal area was40.06m-2·hm-2(2005)<41.77m2·m-2(2010). DBH distribution of different habits species (tree, shrub) showed different types; The mortality rate2.66%of all DBH≥2cm stems is closed to the recruitment rate2.90%. The recruitment rate of median tolerant trees was larger than the intolerant trees and shade-tolerant trees. The mortality of three different living habits species showed significant differences (intolerant trees0.25%, shade-tolerant trees0.88%, median tolerant trees0.53%). The dead stems showed significant correlation with topography at diameter class Ⅰ and no significant correlation with topography at diameter class Ⅲ(DBH≥30cm).