| Bamboo resources are an important part of our country's forest resources.Phyllostachys pubescens,in particular,is a king of China's bamboo resources which is the largest number and the most widely distributed,meanwhile,bamboo species of highest ecological and economic value.Soil fertility is an important environment for plants living environment.It is much important for moso bamboo living after getting basal datas of soil fertility under the management of various measures.However,it is necessary to use the advantage of remote sensing technology to realize the soil fertility estimation of moso bamboo forest land because soil survey method of bamboo forest is mainly field sampling survey method which is unable to realise effectiveness and wide range monitoring of remote.The paper takes moso bamboo in southern China as the reasearch object,by soil and leaf samples obtained field actual survey,to construct alternative estimation technology model of "Remote sensing-forest canopy nitrogen content-soil fertility" after combining physical and chemical experiments of soil and determination of leaves nitrogen content with RapidEye satellite remote sensing image.The research show that:(1)The physical and chemical properties of 59 samples were measured based on the soil samples from the field investigation during 2016,The soil pH of study area is 4.82±0.31,pH value indicated acidic,available K is 83.64±35.53mg/kg?hydrolysis nitrogen is 125.53±67.23 mg/kg?total nitrogen is 2.1±0.9g/kg?organic matter is 39.99±21.73 g/kg?available P is 2.37±0.87mg/kg.(2)The indexes of available K,hydrolyzable nitrogen,available P,pH,organic matter,total nitrogen,water mass content in soil,capillary water holding capacity,field capacity and unit weight were determined comprehensively.By using the principal component analysis to obtain the weight of each index,determine the soil fertility FQI value,the weights of the indicators are arranged from large to small:total nitrogen>capillary water holding capacity>water mass content in soil>field capacity>available K>pH>organic matter>available P>hydrolyzable nitrogen>unit weight.(3)Analyzed the correlation between bands information and the canopy nitrogen content of Phyllostachys pubescens sample point,to construct the model of "remote sensing-forest canopy nitrogen content",the result show that:Two variables equation with B5/B3 and(B1+B2)"as independent variable is:N=18.053+0.476×(B5/B3)-7.257×10-5×(B1+B2)",precision of model for 95.91%,this model is one of the best effect.(4)Changes of nitrogen content in canopy of bamboo leaves were affected by changes in soil fertility,the relationship between soil fertility and canopy nitrogen content in small range of Phyllostachys pubescens forest was studied by linear model and nonlinear model,to construct the estimation model of "forest canopy nitrogen content-soil fertility":FQI=-0.0093×N2+0.5667×N-7.7606,precision of model for 76.07%.(5)Fitting "remote sensing-forest canopy nitrogen content" and"forest canopy nitrogen content-soil fertility" estimation process,to construct the estimation model of "remote sensing-soil fertility":FQI=-0.0093×[18.053+0.476×(B5/B3)-7.257×10-5×(B1+B2)"]2+0.5667×[18.053+0.476×(B5/B3)-7.257×10-5×(B1+B2)"]-7.7606,precision of model for 75.06%,it is feasible to estimate the FQI value of soil fertility in Phyllostachys pubescens by using "remote sensing-forest canopy nitrogen content-soil fertility" alternative ideas.(6)By comparing both measured interpolation soil fertility distribution and remote sensing inversion of soil fertility distribution accuracy and spatial distribution,the results show that:the measured soil fertility distribution map is similar to the soil fertility map retrieved by remote sensing,which shows that the inversion model in the study area has a good fitting effect on the soil fertility FQI value in the study area. |
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