Study On Forest Community Growth Potential And Impact Factor In Liaohe River Nature Reserve

In the nature reserve of liaohe river,eight kinds of typical forest community types as the research object,the paper based on the analysis and research of the different forest community's forests, biodiversity and soil physical and chemical characteristics,carried out related analysis between the influence factors and determined the main factors affecting forest growth,for the research areas of forest resources management and protection provide the theory basis.The research results included the following aspects:(1) The study on forest community species diversity:①The study of a species diversity show that shrubs species richness in various communities were less than the herb layer, especially mixed wood of pine-oak communities is more significant differences. In general, the species richness of Chinese pine pure forest and mixed wood of larch-birch is smaller; herb layer evenness index is the largest community in mixed wood of pine-oak; in the shrub layer evenness index,the biggest is in the spinney,the smallest is in mixed wood of pine-oak and pure forest of oak trees.The trend of two indices about species diversity is similar, the biggest species diversity index in the shrub is broadleaved mixed forest of poplar-birch-oak,the smallest is pure forest of oak trees; the biggest species diversity index in the herb is pure forest of oak trees.②the analysis results of speciesβ:these communities have the biggest community dissimilarity in the shrub layer,they are larch forest and mixed wood of pine-mongolia oak(AF),pure forest community of white birch and mixed wood of pine-mongolia oak(CF),pure forest of mongolia oak and mixed wood of pine-mongolia oak(DF) and mixed wood of pine-mongolia oak and spinney community(FH), the smallest community dissimilarity is the community of pure forest of mongolia oak and spinney which have the most common species and the lowest heterogeneity degree;in the herb layer,the biggest community dissimilarity is mixed wood community of larch-white birch and spinney(EH),the smallest is mixed wood community of larch forest-larch-white birch(AE).(2) The soil physical and chemical characteristics:①Several typical forest community study of soil bulk density are showing rising trend with soil depth increased.Average soil bulk density of various layers in different forest is 0.99～1.19 g/cm3.The smallest soil bulk density is the pure forest of larch,the biggest is spinney.The different pore indexes in different forest communities are showing decreaseing trend with soil depth increased.lt is the largest total porosity in broadleaved mixed forest of poplar-birch-oak,the smallest is in the community of spinney.Chinese pine pure forest has the maximum of capillary porosity,mixed wood of larch-white birch is the minimum.The largest non-capillary porosity is mixed wood of larch-white birch,the smallest is chinese pine pure forest.The largest field moisture capacity is mixed wood of pine-oak,the smallest is spinney.The largest capillary water holding capacity is pure forest of larch,the smallest is spinney.②Soil chemical characteristics:The average soil total N content is 0.2% in the study area of forest communities, N is more abundance; the largest total N content is larix principis-rupprechtii community.Different forest soils alkali solutions of N content of soil have downward trend with the increasing soil.The largest is larix principis-rupprechtii community.The largest total P content in the different layers is larix principis-rupprechtii community,the smallest is broadleaved mixed forest of poplar-birch-oak.The average content of soil available phosphorus is 19.8mg/kg, for most species it can satisfy the need.The average K content is 2.83% which belong to higher contain area. From the comparison of soil available K,the community presents a downward trend with soil depth increased.The different stands have large differences,among them, the largest is pure forest community of oak trees on average available K content;the smallest is 129.63mg/kg in pine forest community.From the soil content of available K and grading standards,the reaserch area has richer content of available K.(3) Forest structure and growth analysis:①Coniferous forest structure and growth analysis shows that:larch stand average diameter is 21.32cm,the skewness coefficient about stand diameter distribution is 0.449,kurtosis coefficient is 0.059,stand diameter distribution structure presents truncated normal distribution.Pine stand average diameter is 20.82cm,the skewness coefficient about stand diameter distribution is 0.227, kurtosis coefficient is 0.215,stand diameter distribution structure basically obeys normal distribution.The tree height of each diameter class present increasing trend with increasing diameter.Fitting goodness of tree height curve is more than 0.8 and fitting effect is better.In the same diameter class,larch forest is higher than pine forest in average height.Fitting growth equation of representative species of needle forest in larch and pine forests at breast height,tree height and volume growth, the result show that fitting goodness is high and above 0.99.②Broadleaved forest structure and growth analysis:In white birch forest,the average diameter is 14.44cm, the skewness coefficient about stand diameter distribution is 0.810,kurtosis coefficient is-0.032,stand diameter distribution structure presents skewed to the right end of the normal distribution.In poplar forest,the average diameter is 14.42cm,the skewness coefficient about stand diameter distribution is-0.239,kurtosis coefficient is-0.452,stand diameter distribution structure basically obeys normal distribution.Multiple correlation about each diameter's average height of fitting curve is above 0.8 in broadleaved forest and fitting effect is better.In the same diameter class,poplar forest is higher than white forest in forest height; Fitting growth equation of representative species of broadleaved forest in white forest and poplar forests at breast height,tree height and volume growth, the result show that fitting goodness is high and above 0.99.(4) According to the Liao River source region 8 communities in different forest types, selecting the 7 types of soil physical characteristics,7 species of chemical characteristics and 5 kinds of plant diversity indicators were analysed and established mathematical model. The results show that, only a soil field capacity and species richness reaches extremely significant level index and species diversity in the biodiversity index H also reaches extremely significant levels, biodiversity index D reached a significant level,while others have not demonstrated notability.(5) Forest growth and the impact of meteorological factors studies have shown that:①in the study area, the fitting with DBH and annual increment results show that climatic factors, the annual average temperature of meteorological factors, annual average maximum temperature and annual average wind speed was elected to equation and explained that these three factors had the greatest impact on the local tree diameter growth. Among them, forest growth and annual average temperature showed positive, but with the average maximum temperature is rendered negative correlation.②On the research area in the main tree species tree, height growth of annual increment and climatic factors fitting results show average annual minimum temperature, annual precipitation, annual average wind speed, annual maximum wind speed, annual mean surface temperature and 20cm annual average ground temperature,6 factors were elected to the equation and illustrated the six factors with height increment having close relation. Among them, the annual precipitation, average annual mean surface temperature, wind speed and height increment was positively correlated.While the average minimum temperature, maximum annual average wind speed, temperature and tree 20cm high growth was negatively correlated.③By stepwise regression analysis we can see, meteorological factors closing volume growth of annual increment is≥10℃temperature, annual average wind speed, the annual maximum wind speed, the average surface temperature and year sunshine hours,5 factors were elected to the equation.Among them, the average surface temperature and volume growth of annual increment was positively correlated, while 10℃temperature, annual maximum wind speed, year sunshine duration and volume growth was negatively correlated.(6) The analysis result for forest productivity and its affecting factors showed:forest productivity appeared increased and then decreased trend with the increase of the stand factors (altitude, slope, stand density); there showed "U"-shaped quadratic polynomial about forest productivity and soil physical characteristics (soil bulk density, soil total porosity, soil saturated water content) (correlation coefficient above 0.7);there showed inverted U-shaped relationship about forest productivity and soil nutrient characteristics (available nitrogen,available P, total K, available K) (correlation coefficient is lower); forest productivity appear decreased trend with the increase of the plant diversity.