Study On Quantitative Relationship Of Main Factors Of Forest Ecosystem In Hebei Xiaowutai Mountain

The forest vegetation in the Xiaowutai Mountain National Nature Reserve of Hebei Province is a typical representative of the temperate forest ecosystem,and the study on the quantitative relationship of the main factors may provide an important basis for the management of forest ecosystem in the said climate zone.The investigation has been conducted on the typical forest ecosystems such as Larix principis forest,Pinus tabulaeformis forest,Betula platyphylla forest,P opulus davidiana forest, Betula-Larix mixed forest and other broad-leaved mixed forests in the Xiaowutal Mountain.Based on the analyses on the main factors such as soil physical and chemical properties,species diversity and tree growth as well as the correlation of these factors,some proposals have been put forward for the healthy management of the Xiaowutai Mountain forest ecosystem.The main research conclusions are as follows:(1) The research on soil characteristics indicates that①Soil particles in different forest communities are mainly 0.25～2mm grade and≥2mm grade.The deeper the soil layer,the more the particles of≥2mm grade.②The soil bulk density tends to increase as the soil layer deepens.The difference is not big among different stands and different soil layers with an average range of 0.78～1.08g/cm~3,and the soil is fairly loose.③The soil water first increases and then decreases as the soil layer deepens,and varies among different stand and different soil layers.④The nitrogen is insufficient in forest soils and the content of the rapidly available nitrogen trends downwards as the soil layer deepens.The rapidly available P content was stable,between 0.01g/kg～0.02g/kg.The rapidly available K content trends downwards as the soil layer deepens.The available K in coniferous forest soils is more than broad-leaved forest soils.The soil organic matter has shown a downward trend with the increases of soil depth and the larch soil organic matter content is highest.The soil in this area belongs to the acidity and the neutral soil and the soil pH value trends upwards as the soil layer deepens.(2) Stand structure and forest growth:①The stand diameter structure is near the normal distribution.The diameter structure of high-altitude stand is near the truncated normal distribution,the diameter structure of high-altitude coniferous forest basically belongs to the normal distribution,and the diameter structure of low-altitude coniferous forest shows right deviation.②The tree height of low-altitude broadleaved forest is more than that of high-altitude broad-leaved forest.On the contrary, the mean height of low-altitude coniferous forest is less than that of high-altitude coniferous forest.(3)The plant species diversity:①The analyzing result ofαspecies diversity indicates that the shrub species richness in each community was smaller than that of the herb species.Betula platyphylla forest and Betula-Picea mixed forest have small species richness.Pinus tabulaeformis forest and Quercus forest have fairly big species evenness,and the herb layer and the shrub layer vary in the species evenness without regular change.The two indexes of species diversity have similar change trend.The species diversity index of Quercus forest,Populus davidiana forest and Larix-Betula mixed forest are fairly high,and the lowest is Picea-Betula mixed forest.②The analyzing result of the species similarity:AB=EG=EF=FK=IJ,the similarity coefficient between these communities is the biggest,that is to say,theβ-diversity is the smallest and the heterogeneity degree is the lowest.There are few common species between Populus davidiana forest and Larix-Betula mixed forest and the similarity was the smallest.(4) Relationship between physical and chemical properties of soil:①There is a positive correlation between soil capillary water and rapidly available N,but a negative correlation between soil capillary water and soil available P.There is a positive correlation between soil field water and rapidly available N,organic matter and pH value,but a negative correlation between soil field water and rapidly available k.②The soil organic matter and≥4mm,≤0.1mm and 0.25-1mm particle size soil show negatively correlated,likewise,available k and≥4mm,≤0.1mm soil particle size soil show an inverse correlation.③Soil natural water and soil capillary water show inverse correlation with≥4mm,≤0.1 mm particle size soil.④The semi-decomposed litter has a positive correlation with total P,available N and total N.The decomposed litter has a positive correlation with total P,but an obvious inverse correlation with the pH value.(5) Relationship between biodiversity and habitat:①The main factors affecting biodiversity are altitude,canopy density,slope position and slope aspect.The biodiversity reduces as altitude increases, particularly the diversity index.②The main nutrient factors affecting diversity are total N content and pH value.③In the variable group of soil particle size,the main factors affecting diversity the soil particles of≥4mm,≤0.1mm and the 0.15～0.25mm. (6) Relationship between forest growth and habitat factors:①Each decomposed layer of litter has a different correlation with stand growth indicators.②All stand growth indicators have a positive correlation with total P,available k and pH value.③Stand growth has a positive correlation with the soil particles of≤0.1mm and 1～2mm size,but an obvious negative correlation with the soil particles of≥4mm,2～4mm and 0.1～0.154mm size.Based on the above-mentioned research results,this paper briefly puts forward some health management measures about forest ecosystem.