| Forest ecosystems,as the largest carbon reservoir on land,play an important role in mitigating climate warming.Shennongjia Forest Area is rich in forest resources and occupies an important position in the process of promoting carbon peaking and carbon neutrality in Hubei Province.The dynamic change of forest vegetation carbon storage is an important indicator reflecting the benefits of forest carbon sinks in forest areas,and through scientific and reasonable management,forest quality can be improved and the potential of forest carbon sinks can be fully utilized.In this study,using the forest type II survey data of Shennongjia Forest Area in 2009 and 2019 and the fixed sample data of continuous inventory of forest resources in 2014,the carbon storage of forest vegetation in Shennongjia Forest Area was estimated by the biomass conversion factor method(IPCC method),and the changes and distribution characteristics of forest carbon storage and carbon density in the forest area from 2009 to 2019 were analyzed.An index system for evaluating the potential of forest carbon sink management is constructed,and the comprehensive weights combined with the analytic hierarchy method and the entropy method are used to determine the index weights,and the potential of forest sink enhancement management in Shennongjia forest area is evaluated.According to the dynamic changes of carbon storage in forest areas and the evaluation results of carbon sink management potential,the measures for increasing the foreign exchange management of forests in forest areas are proposed from three aspects:improving forest carbon absorption capacity,carbon conservation capacity and carbon management capacity.The main results are as follows:(1)In 2019,the area of Shennongjia forest area increased by 7.2×10~3 hm~2 and0.08×103 hm2 compared with 2009,respectively,and the total area of shrub forest and bamboo forest decreased by 8.8×10~3 hm~2.The transformation of shrub and bamboo forests into unforested,unsubstantiated woodlands and non-forested land due to engineering construction is the main reason for the decrease in the total forest area in forest areas.In the past 10 years,the net increase in carbon storage in Shennongjia forest area was 55.602×104t,the average annual net carbon sequestration was 5.56×10~4t,the carbon density of forest vegetation layer increased by 18.23t/hm~2,and the carbon density in all parts of the forest area was mainly increasing.(2)Compared with 2009,the natural forest area increased by 8.79×10~3hm~2,and the carbon storage and carbon density increased by 558.17×10~4t and 18.29 t/hm~2respectively compared with 2009.The increase in carbon storage and carbon density in young forests in natural forests was largest,at 477.68×10~4t and 24.42 t/hm~2,respectively.Among the stand types of different dominant tree species,the area increase of other hard broad forest types was 68.12×10~3 hm~2,and the area of broad-leaved mixed forests decreased by 45.54×10~3 hm~2,and the carbon storage and carbon density of other hard broad forests increased by 559.31×10~4t and 26.96 t/hm~2,respectively,and the carbon density of other pine species decreased by up to 24.57 t/hm~2.In the past 10 years,the main body of carbon sequestration in natural forests has been juvenile forests,contributing 80%of the carbon sequestration.(3)Compared with 2009,the natural forest area increased by 8.79×10~3hm~2,and the carbon storage and carbon density increased by 558.17×10~4t and 18.29 t/hm~2respectively compared with 2009.The increase in carbon storage and carbon density in young forests in natural forests was largest,at 477.68×10~4t and 24.42 t/hm~2,respectively.Among the stand types of different dominant tree species,the area increase of other hard broad forest types was 68.12×10~3 hm~2,and the area of broad-leaved mixed forests decreased by 45.54×10~3 hm~2,and the carbon storage and carbon density of other hard broad forests increased by 559.31×10~4t and 26.96 t/hm~2,respectively,and the carbon density of other pine species decreased by up to 24.57 t/hm~2.In the past 10 years,the main body of carbon sequestration in natural forests has been juvenile forests,contributing 80%of the carbon sequestration.(4)From 2009 to 2019,the area of plantations in Shennongjia forest area decreased by 1.59×10~3 hm~2,but the carbon storage and carbon density of plantation forests increased by 8.16×10~4t and 15.44 t/hm~2,respectively.The carbon stock of near-mature forests increased the most in plantations,with an increase of 3.98×10~4t,the carbon density of juvenile forests increased the most,with an increase of 16.4 t/hm~2,and the carbon density of overripe forests decreased but still reached a maximum of 40.36 t/hm~2.Among the different dominant tree species,the area of other soft broad-leaved forest types increased the most,with an increase of 368.09 hm~2,the area and carbon storage of Masson pines decreased the most,by 2548.61 hm~2 and 4.711.65×10~4t,respectively,and the carbon storage of broad-leaved mixed forests increased the most,with an increase of 1.65×10~4t;the carbon density of other hard broad types increased by 20.96t/hm~2,and the carbon density of spruce forests decreased by 38.60 t/hm~2.In the past 10years,the main body of carbon sequestration in plantation forests has been near-mature forests,contributing 48.77%of carbon sequestration.(5)Among the three Nature-based Solution(Nbs)for forest carbon sink management,the area of the forest management pathway is the largest,which is 279.40×10~3 hm~2,the area of the forest transformation pathway is the smallest,which is9.31×10~3 hm~2,and the area of the new afforestation pathway is 16.56×10~3hm~2.The forest management channel generated 554.73×10~4t of carbon sequestration and 26.84×10~4t of carbon loss,the net carbon sequestration was 527.88×10~4t,the new afforestation generated 63.11×10~4t of carbon sequestration,and the forest conversion caused 22.43×10~4t of carbon loss.In different regions,the maximum increase in carbon density brought by Xinhua Forest Farm through forest management channels was 39.66t/hm~2,the maximum net carbon sequestration generated by the forest management channel of Dajiu Hu Lake Management Office was 90.61×10~4t,the maximum area of new afforestation in Shennongding Management Office was 3.85×10~3 hm~2,and the new direct carbon sequestration was 13.88×10~4t,while the maximum carbon loss caused by forest transformation in Dajiuhu Management Office was 3.32×10~4t.In general,among the three natural solutions to forest carbon sink management,the increase in unit carbon density generated by the new afforestation approach is greater than that of the forest management pathway,which is a relatively efficient means of increasing sinks at present,but with the gradual reduction of the land area available for new afforestation in the future,the main way to increase the sink in the forest area is forest management activities and reduce forest transformation.(6)An index system was constructed to evaluate the management potential of arborvitae forests with stand characteristics,stand stability,and site conditions as the criterion layer,stand density,depression closure,stand carbon density,age group grade,community structure,herbaceous cover,shrub cover,hybrid grade,soil layer thickness,humus thickness,and altitude as the index layers.The comprehensive weights of the evaluation indicators were obtained through the combination of the analytic hierarchy method and the entropy method.In the criterion layer,the highest stand stability weight is 0.511,the stand characteristic weight is 0.345,and the lowest site condition weight is 0.143,so the focus of increasing the management potential of forest stand carbon sinks is to improve the stability of forest stand,followed by improving forest stand characteristics.In the indicator layer,the weights of the five indicators of stand density,age group level,community structure,herbaceous cover and shrub cover exceeded0.100,so the key indicators of forest management in forest areas to improve the carbon sink capacity of forest areas are to improve stand density,optimize the age structure of forest stand,maintain the integrity of community structure,improve shrub cover and prevent soil erosion in forest stands.(7)The evaluation of the carbon sink management potential of arborvitae forests shows that the carbon sink management potential of more than 50%of the forest stand area and the small class is general,high and high grade,indicating that the overall potential of arborvitae carbon sink management in forest areas is high,and the carbon sink capacity of arbor forests in forest areas has greater room for improvement.In the criterion layer,stand stability and improved stand characteristics are the focus of increasing carbon sink capacity of tree forests in forest areas.Among the indicator layers,soil layer thickness,community structure,shrub cover,stand carbon density,age group grade and stand density are the key points for improving the carbon sink capacity of arborvitae forests in forest areas and implementing carbon sink management.Among the different forest categories,the general commodity forest carbon sink management has the largest room for improvement,followed by key public welfare forests.Among the different origins,plantation forests are the focus of carbon sink management and improving carbon sequestration capacity.From a regional point of view,Hongping Town,Songbai Lin Chang,Songbai Town,Songluo Township carbon sink management has a large space for improvement,is the key area for the implementation of foreign exchange management measures in the forest area;the status quo of tree forests in Laojunshan Management Office,Muyu Forest Farm,Warm Water Forest Farm,Xinhua Forest Farm and other places is relatively good,and it is a key area for carrying out forest protection,curbing forest transformation and forest land degradation.(8)According to the evaluation results of the carbon sink management potential of arborvitae forests,combined with the three natural solutions of forest carbon sink management,the measures and strategies to increase foreign exchange in Shennongjia forest area,such as afforestation and reforestation of Shennongjia forest area,forest sink increase management,natural forest protection and reduction of forest transformation,and strengthening of natural disaster prevention and control in forest areas are proposed from three aspects:improving the carbon absorption capacity of forest areas,carbon conservation capacity of forest areas and carbon management capacity of forest areas. |
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