Research On The Management Model Of Typical Soil Erosion Areas In The South Based On Carbon Stock

The evaluation of the effectiveness of soil erosion control is an important guarantee for the effective promotion of regional soil erosion control.The traditional indicators for evaluating the effectiveness of soil erosion control are mainly vegetation cover,which contradicts the phenomenon of"green from afar,but water and soil flowing at close range",that is more common in southern red soil areas.This is a contradiction to the current phenomenon of"green from afar,water and soil flow from near"in southern red soil areas.Forest carbon stock is an important indicator of ecosystem health and resilience,and the quantification of carbon stock can be used to enrich the methods and theories of remote sensing evaluation of soil erosion control and restoration effectiveness,and provide a basis for remote sensing evaluation of control effectiveness of regional soil erosion.To this end,the study takes the Horsetail pine managed forest in Hetian Township,a southern soil erosion area,as an object,and reveals the mechanism of spatial conversion of UAV images to satellite images by exploring the correction of Landsat satellite images by the high spatial resolution of UAVs;based on the actual ground measurement data,the principle of pseudo-invariant features is used to realize the applicability of the Horsetail pine carbon stock estimation model of 2022a to convert in2011a and 2017a.Based on the theory of ecosystem carbon balance,we indirectly estimate the soil carbon stock of forested land in the same period,and on this basis,we systematically analyse the management effectiveness of typical soil erosion control measures in the south（inefficient forest renovation,ecological forestry,afforestation and grass planting,closure and integrated governance）with tree carbon stock and soil carbon stock.The main conclusions of the study are as follows:（1）The high spatial resolution characteristics of UAVs can provide more detailed forest structure information to satellite images,and the satellite images are corrected by resampling the UAV images with a view to improving the forest carbon stock estimation results.The UAV images were resampled to the same spatial resolution as Landsat 8 satellite images,and the correction coefficients for each band and vegetation index were 0.159Blue,0.436Green,0.746NIR,0.395Red,0.941PVI,0.565EVI,2.140RVI,1.874NRI,1.278NDVI,1.383GNDVI,0.416YELLOW;the results of the construction of the remote sensing estimation model of tree carbon stock showed that the accuracy of the remote sensing estimation model of tree carbon stock improved after the UAV correction,and the average relative accuracy and the mean estimation accuracy improved by 3.01%and 1.65%respectively.（2）The study used the corrected Landsat satellite imagery,based on the measured arboreal standard land carbon stock,and determined the factors of PVI,NRI,NDVI,GNDVI and CVI as the model independent variables through correlation analysis,and synthesized the arboreal carbon stock estimation model.The model was y=0.005CVI^7.46with a fitted R²of 0.66.Using the pseudo-invariant characteristic principle,the arboreal carbon stock estimation models of 2011a and 2017a were derived with 2022a as the benchmark to realize the arboreal carbon stock inversions for three periods.Tree carbon stocks of 2011a,2017a and2022a were 13.93 t/hm²,18.39 t/hm²and 28.01 t/hm²,respectively,showing an overall increasing trend,indicating that that the erosion control conducted during this period was effective.（3）Due to the effect of forest cover,forest floor soil organic carbon needs to be inverted by an indirect estimation method.The indirect estimation of soil organic carbon in woodlands was achieved using NPP-soil base respiration and soil base respiration-soil organic carbon.The best estimation model for soil organic carbon in the Horsetail pine woodland was y=2.403 X^1.327_{soil basal respiration},with R²of 0.56,and the average relative accuracy and mean estimation accuracy were 82.82%and 97.31%,respectively.2011a,2017a and 2022a soil carbon stocks were 31.05 t/hm²,33.72 t/hm²,37.71 t/hm²,respectively,showing an overall increasing trend,showing an overall increasing trend,indicating that the erosion control carried out during this period has achieved some success.（4）According to the statistical analysis of soil erosion control in Hetian Township,it can be seen that soil erosion control measures in Hetian Township are mainly divided into five types:closure,low efficiency forest renovation,afforestation and grass planting,water conservation forest and grass,and integrated governance.2011a-2022a,the carbon stock of trees and soil in the closure area were 13.65 t/hm²,19.85 t/hm²,33.01 t/hm²and The carbon stocks of trees and soils in afforested areas were 4.29 t/hm²,19.00 t/hm²,20.46 t/hm²,29.36 t/hm²,34.36 t/hm²,35.17 t/hm²,respectively.Soil carbon stock and tree carbon stock in low-efficiency forest rehabilitation areas were 3.78 t/hm²,13.77t/hm²,19.47 t/hm²and 27.65 t/hm²,31.44 t/hm²,34.58 t/hm²,respectively;tree carbon stock and soil carbon stock in water conservation forest and grass areas were 3.05 t/hm²,11.38 t/hm²,16.99 t/hm²and 26.79 t/hm²,29.98 t/hm²,respectively.The carbon stocks of trees and soils in integrated governance areas were 3.43 t/hm²,15.13 t/hm²,19.07 t/hm²and 27.26 t/hm²,32.01 t/hm²,35.31 t/hm²respectively.（5）To investigate the effect of the treatment measures,a control（untreated area）was added for analysis and comparison.In the relationship between the total growth rate of forest carbon stocks,it was found that integrated governance>inefficient forest renovation>water conservation forestry>afforestation and grass planting>closure>no treatment measures,indicating that carbon stocks grew fastest in areas that had been repeatedly treated with different measures,followed by inefficient forest renovation.By analyzing the relationship between the underground carbon pool and the above-ground carbon pool,it was found that the relationship between the underground carbon pool and the above-ground carbon pool was relatively stable in areas that had not undergone treatment measures,while in 2011,the underground carbon pool was 6.84 to 8.78 times larger than the above-ground carbon pool under measures such as low-efficiency forest renovation,afforestation and grass plantation,water conservation forestry and grass,and repeated treatment,except for closure measures,indicating that the relationship between the above-ground and underground carbon pools was unstable,which was not conducive to fully utilizing the role of regional forest carbon sinks.After years of treatment,the ratios of below-ground to above-ground carbon stocks in the areas of inefficient forest renovation,afforestation and grass plantation,water conservation forestry and grass,and repeated treatment measures in 2017 and 2022 were 2.28,1.81,2.63,2.12 and 1.78,1.71,1.96,1.85,respectively,all of which have a tendency to decrease.The relationship between above-ground and below-ground carbon stocks also demonstrates the effectiveness of different treatment measures.With repeated treatments and water conservation treatments being more effective and improving the forest carbon stocks over the11-year period,the health of the regional forest system gradually recovers.