| Global warming will redistribute global precipitation,glacier and permafrost ablation,sea level rising,which not only endanger the balance of natural ecosystems,but also threaten the survival of mankind.In response to global climate change,the international community mainly adopts two major measures: direct reduction and indirect reduction,indirect emissions is forest to absorb CO2,and forests as the main part of terrestrial ecosystems,which have a unique role in regulating global climate and carbon balance and mitigating global climate change.Therefore,monitoring forest biomass carbon storage is particularly important.In the four key state-owned forest areas in China,Inner Mongolia Daxinganling forest area is the largest area,which has the highest latitude,the most concentrated state-owned forest land and ecological status is the most important national forest ecological function area.Larix gmelinii is the most representative forest vegetation type under dry and cold climate,and it is also representative of northern forest in China.Therefore,we used the methods of measuring,remote sensing,model simulation to monitor the carbon storage of Larix gmelini forest,explored the advantages and disadvantages of each method and the applicable conditions.We chose the measured method to study carbon storage and distribution characteristics of each layer of Larix gmelinii forest(different age,slope position,forest type)in the Daxing'anling forest area.Meanwhile,the effects of human disturbance factors(stand density,harvesting method and newer afforestation method)on carbon storage and carbon layer distribution characteristics of Larix gmelinii forest were analyzed.This is significant to accurately evaluate the functions and value of forest carbon sinks in Daxing'anling forest area and to develop strategies of addressing global climate change.The main conclusions as follows:(1)Monitoring of Carbon Storage in Larix gmelini Forest Based on the Methods of Measuring,Remote Sensing and Model SimulationIn this study,the carbon storage of Larix gmelinii plantation was monitored by measured method,remote sensing method based on Landsat-8 remote sensing image and model simulation based on allometric growth model.The remote sensing method was used to establish a total of six models,R2 was between 0.58 and 0.74,model accuracy was between 80.6 and 84.7%.The allometric growth model was used to establish the exponential function model with the DBH as the independent variable,it's R2 was between 0.92 and 0.98,and the accuracy was between 82.88 and 96.11%.By analysis and comparison,we can see determined coefficient and accuracy the model simulation method are higher than the remote sensing method.In future researches,on the basis of the small-scale study,we should first select the measured method to measure the forest carbon storage.If the vegetation is not destroyed,the simulation model should be considered for forest carbon storage monitoring.If we monitor the large-scale forest carbon storage,in the absence of more easily measured parameters such as DBH,we can choose remote sensing to monitor.(2)Carbon Storage and Distribution of Carbon Layers in Larix gmelini ForestThe total ecosystem carbon storage of different ages of Larix gmelinii natural forest was between 350.16 and 713.18 t·hm-2,the vegetation layer was between 92.64 and 376.28 t·hm-2,the litter layer was between 2.25 and 3.69 t·hm-2,the soil layer was between 255.27 and 333.77 t·hm-2.The total carbon storage of Larix gmelinii plantation was between 261.98 and 323.78 t·hm-2,the vegetation layer was between 5.0 and 59.18 t·hm-2,the litter layer was between 0.22 and 0.45 t·hm-2,the soil layer was between 242.01 and 267.43 t·hm-2.According to the results of analysis and comparison,the total ecosystem carbon storage of vegetation layer,soil layer in different age groups increased with the increasing age,while the litter layer had no significant change.The total ecosystem carbon storage of different slope in Larix gmelinii natural forest were: under the slope(281.72 t·hm-2)> middle of slope(243.28 t·hm-2)>above the slope(214.24 t·hm-2),the vegetation layers were: 32.63?37.28?70.36 t·hm-2,the litter layers were: 6.93,5.26,6.90 t·hm-2,the soil layers were: 242.17,200.74,136.98 t·hm-2.By analysis and comparison we can see,the total carbon storage and soil layer of different slope decreased with the slope position,while the vegetation layers was opposite,different slope positions had no significant effected on the distribution characteristics of tree layer and ecosystem carbon storage.The total carbon storage of different forest types of Larix gmelinii were: Betulfrutic-Larix gmelinii Forest(334.79 t·hm-2)>Bryaceae-Larix gmelinii Forest(226.24 t·hm-2)>Ledum palustre-Larix gmelinii Forest(167.44 t·hm-2)> Grass-Larix gmelinii Forest(119.55 t·hm-2),the vegetation layers were: 81.15,20.20,63.60,49.80 t·hm-2,the litter layers were: 2.67,0.93,4.87,1.22 t·hm-2,the soil layers were: 250.96,205.11,98.97,68.54 t·hm-2.The law of total carbon storage and soil layer change was the same,Betulfrutic-Larix gmelinii Forest was the largest,and the Ledum palustre-Larix gmelinii Forest was the least.(3)Effects of human interference on carbon storage and distribution of Larix gmelinii ForestThe total carbon storage of Larix gmelinii plantation ecosystem in different forest stands were between 182.01 and 338.38 t·hm-2,the vegetation layer was between 3.70 and 80.18 t·hm-2,the litter layer was between 0.14 and 1.43 t·hm-2,and the soil layer was between 178.17 and 256.76 t·hm-2.According to the results of analysis and comparison,stand density has a significant effect on carbon storage and its distribution characteristics.The vegetation layer,litter layer and ecosystem carbon storage increased with the increase of stand density,while the understory vegetation layer was opposite,the soil carbon storage was no more obvious changes in the law.The total carbon storage capacity of Larix gmelinii in different harvesting methods was 176.99,120.73,22.49 t·hm-2,the vegetation layers were 63.65,29.45,11.81 t·hm-2,the litter layers were 4.91,2.98,2.38 t·hm-2,and the soil layers were 108.43,88.30,8.3.30 t·hm-2.By analysis and comparison we can see,compared with the original undeveloped forest,the ecosystem total carbon storage of vegetation layer,litter layerand soil layer decreased significantly(P <0.01).The total carbon storage of Larix gmelinii plantation ecosystem in different afforestation methods was between 257.85 and 316.19 t·hm-2,the vegetation layer was between 5.04 and 57.51 t·hm-2,the litter layer was between 0.20 and 0.85 t·hm-2,and the soil layer was between 244.00 and 257.92 t·hm-2.By analysis and comparison we can see,different afforestation methods had a significant effect on carbon storage and distribution characteristics of carbon layers.The carbon storage of carbon layer was the smallest in the wetland,in the young forest,the vegetation layer,the soil layer of carbon storage was the largest in burned fire sites and in the middle of the forest stage,the largest was barren wasteland.There is no consistent change law of the litter layer carbon storage under different afforestation methods. |
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