| In order to find more measure of monitoring and evaluation of forest public welfare and correlative key factors,cut down research cost,improve the efficiency of common office equipment,this research proposed a method which use common office equipment like computer camera and scanner to measure the width of tree ring,forest canopy density and soil erosion rates.The paper using recognized equipment examined precision,and completed the initial application.Compared to Tree Ring Analysis system,the measurement accuracy of digital images photogrammetry of tree ring width is as high as 94.28%,and can satisfy the demand of correlative research.The efficiency of the new method is 1.1～1.5 times of the TRAS method and the cost is 1/10～1/15 of the TRAS method.The initial application of the new method made in mountain area in northern Hebei province shows that:the average temperature and rainfall in the basin act as the limiting factors of tree growth during May and Sep,which is in accordance with climate characteristics of the studied semi-arid sub-humid continental monsoon type climate plateaus climatic zones.And the correlation coefficients of the reconstruction value and actual value of average temperature and total rainfall from May to Sep is 0.917 and 0.822.Using the tree-ring index we rebuilt the average value air temperature and rainfall from May to September in Jibei Mountain and prolonged the datum of sixteen years from 1940 to 1955 of average value air temperature and rainfall.Using Canopy Analysis System test the precision of digital images photogrammetry of canopy closure the result show:the canopy images obtained by fish-eye camera can record canopy information accurately,the usage of Photoshop software to calculate the degree of forest canopy system hasn't any system deviation and the accuracy of the new method can be as high as 95%.In height range of 90～130cm,the measurement results is almost exactly the same,and the operation of equipment is more convenient in this range. When the tree trunk image was separated from the canopy measurement zone,only coniferous forest and low canopy closure forest has a greater impact on the measurement results.Different testers' results in independent tests shows that the stability coefficient of the new method can achieve as high as 92.86%.The observation of canopy closure of fixed plots were finished using the new method in Fangshantuqiaogou basin.Those measure accumulate the basic data for the pilot demonstration projects of soil and water conservation of semi-arid area of Loess Plateau hilly,anti-drought,afforestation and drought runoff forestry technology.In the artificial simulation of rainfall conditions,the experiment of digital close range photogrammetry of soil erosion rate show that:the accuracy of pin erosion exposed (buried) a high degree can be achieved more than 97%and the soil erosion accuracy 92.77%.In Yanqing,Beijing Science and Technology Park of Soil and Water Conservation, we carried out the initial application of the new method.In a total of 5 times of rainfall observation experiments,compared to measured value,the accuracy can achieve 89.35%. the accuracy of measuring are not effected obviously by different erosion pins laid the density.Using erosion pins for the monitoring soil erosion,the distance should be controlled under 1m and the number of erosion pin of each line should be more than 5.
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