Research On Monitoring Of Forest Resource Area Change Based On Geographical Grid

Forest resources provide abundant material resources and tourism resources for human production and life.At the same time,they play an important role in regulating ecological balance and purifying human living environment,and have high economic value and ecological value.With the rapid development of geo-grid technology,it is of great significance to monitor the change of forest resources area.Based on geographic grid technology,this study uses high spatial resolution imagery combined with systematic sampling technology to conduct research on the change of forest resource area in Qingtian County and Yongjia County by means of literature review,field survey and comprehensive analysis.The rapid estimation of forest coverage,tree species structure and no forest land area shows that:(1)From the up-scaling overall precision analysis of the sampling area of different unit sizes in Qingtian County and Yongjia County,it can be seen that under the premise of ensuring the sampling accuracy of 95%,the influence of unit size on the up-scaling overall precision and stability of sampling extrapolation is not significant.The extrapolation estimation accuracy obtained by using the cell size of 25m×25m is the highest;reducing the sample cell size can significantly improve the accuracy of the sampling extrapolation;the land class within the 25m×25m sampling unit can be treated as a pure land class.The sampling accuracy is more than 95%,which is the best sampling unit size.(2)From the monitoring and analysis of the area change of forest types(forest types)in Qingtian and Yongjia counties,the changes in the area and relative change of the area and forest type obtained from the sampling results and the changes in the area and forest type obtained by the measured results are The relative changes are similar,the relative error of bamboo forest,special shrub forest,sparse irrigation and no-forest area is relatively large,the average precision is above 90%,the relative error of arbor forest area change is small,and the precision is above 95%.(3)It can be seen from the analysis of recognition accuracy that the high-resolution satellite imagery and the shadow of the aerial film have great interference to the land type identification.It is necessary to consider the addition of terrain factors and human activity influence factors to identify the land type;the arbor forest in the project area The area ratio is above 70%,and the proportion of bamboo forest and irrigated forest area is below 5%.The classification of arbor forest and bamboo forest and sparse forest in the sampling process is confused,which can easily lead to huge errors in bamboo forest area and sparse forest area.When the data of the second class survey of forest resources was compiled,the estimation of the area of the forestless area was affected by the plot of the land and the forest land,and the plot of 25m×25m was more elaborate than the small section of the forest resource.