Gis-based Evaluation And Analysis Of Windthrow Hazarel In Liangshui Nature Reserve

Health forest is fundamental for sustainable development of socio-economic and forest health assessment has becomes one of the hotspots of modern forestry development. Recently, a series of ecological and environmental problems, such as soil erosion, desertification, floods and droughts, loss of biodiversity, are on the growing and thereby have negative influence on social security, economic development and threads life quality and environment. Since healthy forest could effectively avoid some natural disasters, the integration of ecological, economic and social benefits has become the key attention in forestry for international society. Hence, forest health assessment has also become the new concept to promote the sustainable and healthy development of regional economy.In this study, geographical weighted regression (GWR) model and ordinary least square (OLS) model were established and assessed using category B survey data in Liangshui nature reserve of2009. Windfall accumulation of every subcompartment was calculated using GIS.In model development, stepwise method was applied to find most significant factors for windfall accumulation in Liangshui natural reserve. The most significant factors, including average diameter at breast height, accumulation of living trees, slope and composite factor of aspect and slope, were selected. Based on these significant factors, GWR and OLS were developed. Results showed that GWR outperformed OLS according to fitting and prediction results. The estimates of GWR parameters were visualized using ArcGIS9.3, which demonstrates spatial heterogeneity of windfall accumulation per hectare based on the average diameter at breast height, slope, aspect and accumulation of living tree. The response variable was analyzed directly using explanatory variables within different sub-regions in study area. The larger average diameter at breast height of subcompartment is, the smaller influence on windfall accumulation is; the larger slope, accumulation of living trees and composite factor of aspect and slope are, the larger influence on windfall accumulation is.In this study, the forest disaster assessment standards proposed by the national forest resources inventory technical requirements, site conditions, geography and climate were taken into consideration. Windfall disaster was divided into four ranks:no disaster, slight disaster, moderate disaster and severe disaster. The windfall disaster spatial database of Liangshui nature reserve was established. Disaster rank distribution map, slope map, aspect map and stand density distribution map were used for analyzing disaster ranks and distribution. Results showed that3subcompartments are sever disaster area,34are moderate disaster area,363are slight disaster area,18are no disaster area in418forest subcompartments (There are437subcompartments in total and19subcompartments are non forest land). The sever windfall disaster area mostly has steep slope and small stand density ranging from0.51-0.60; on the other hand, slight disaster area usually has gentle or flat slope and large stand density ranging from0.71-0.90. Besides, the distribution of windfall disaster rank has certain relationship with the distribution of functional area in Liangshui. Generally speaking, the slight windfall disaster located in plantation trial area, most sever and moderate disaster located in core area. The virgin and secondary forest trial areas also have slight windfall disaster ranks.