Carbon Storage Features Of High-efficiency Characteristic Forests And Carbon Sequestration Forestry Cultivation Techniques In The Karst Rocky Desertification Areas

Karst rocky desertification restricts the regional development of South China Karst,and improving the ecological environment is a major issue that must be solved first in the development and construction of this area.Screening suitable,high-efficiency,native tree species,restoring forest-shrub-herb vegetation and developing carbon sink forest industry is an effective way to alleviate the contradiction between people and land in the region,promote the positive succession of plant communities,slow down the greenhouse effect and regulate regional carbon balance.Forest carbon storage is a breakthrough and entry point for forest carbon sink value estimation,carbon sink forest selection and carbon sink forestry cultivation research.According to the basic principles of physical geography,restoration ecology,forest cultivation,and tree-ring ecology,combined with ecological restoration theory,biological allometric growth theory,marginal benefit theory,using biomass relative growth equation method,tree ring method,principal component analysis,nonlinear regression analysis,stepwise regression analysis and path analysis,based on the background survey in October 2017,we have chosen nine representative plantations of Tectona grandi,Cupressus funebri,Cladrastis platycarpa-Cotinus coggygria,Pinus armandii,Betula luminifera,Pinus armandii-Betula luminifer,Pinus massoniana-Tilia nanchuanensis,Pinus massoniana-Robinia pseudoacacia,Pinus massoniana-Cunninghamia lanceolata in the study areas to carry out the pilot demonstration study from April 2018 to November 2019.In the mountainous area of Guizhou Plateau,which represents the overall structure of the environment of South China Karst,the three types of karst ecological environment types of Bijie Salaxi,Guanling-Zhenfeng Huajiang,and Shibing Karst were selected as the research areas.In each quarter of the quarter,continuous field observation and data collection were carried out on 27 plots in three research areas,and 1287 samples of 28 indicators were analyzed experimentally.Centering on the basic frontier research of characteristics of high-efficiency forest carbon storage and carbon sink forestry cultivation,common key technology research and development,application demonstration and industrialization promotion,we carried out full-chain design,integrated deployment and sub-module advancement research and focused on systematic research on aspects such as high-efficiency and characteristic forest carbon storage allocation patterns,indications of functional traits on carbon sequestration capacity,carbon sink forestry cultivation technology research and development,application demonstration and verification,etc.,to provide scientific and technological reference for national rock desertification control forestry projects.?1?The arbor layer and soil layer are the main carbon pools in different forest types,and the proportion of shrubs,grasses,and l_itter layers accounts for less than 3% of the total carbon pools.The karst rocky desertification area has shallow soil and high gravel content,which results in the soil carbon pool not showing obvious advantages over the tree carbon pool.In the potential-light rocky desertification area,coniferous and broad-leaved mixed forest can effectively improve site environment and increase l_itter and soil carbon storage.In the medium-intensity rocky desertification area,Tectona grandis forest carbon storage is highly concentrated in the arbor layer and has significant advantages over other forest types with a good carbon sequestration effect.In the no-potential rocky desertification area,the Pinus massoniana-Tilia nanchuanensis mixed forest has a higher carbon sequestration advantage,while Pinus massoniana-Cunninghamia lanceolata are rich in the soil carbon pool.Pinus massoniana-Robinia pseudoacacia mixed forest has weak carbon sequestration capacity.The distribution of carbon storage by diameter structure and tree age structure can better explain the variation of tree carbon storage between different rocky desertification areas and different forest types.The research results can provide a theoretical basis for the selection of carbon sink tree species.?2?Forest tree layer carbon storage of high-efficiency characteristic is significantly positively correlated with terrain factor-elevation,climatic factors-annual average temperature and annual precipitation are extremely significant and significantly negatively correlated,and biological factor-average DBH and average tree height are significantly positively correlated.Total nitrogen and soil organic carbon are the main controlling factors affecting carbon storage in Bijie Salaxi research area.In Guanling-Zhenfeng Huajiang research area,total nitrogen,total phosphorus,available phosphorus,hydrolyzed nitrogen and soil bulk density are the main controlling factors affecting arbor carbon storage.In the Shibing Karst research area,available potassium,total potassium and soil organic carbon are the main controlling factors affecting arbor carbon storage.In Karst rocky desertification area,the obvious surface nutrient accumulation effect of soil nutrients is conducive to the improvement of forest carbon storage.Coniferous and broad-leaved mixed forests have effectively improved the soil nutrient status of the understory.The soil nutrients of Cladrastis platycarpa-Cotinus coggygria are in supersaturated state,which reduces carbon sequestration capacity.The research results can provide a reference for the research on the impact factors of forest carbon storage in karst rocky desertification areas,and provide a basis for the regulation of soil nutrients in carbon sink forests.?3?Most of plant morphological traits?crown area,wood density?,photosynthetic traits?maximum net photosynthetic efficiency,maximum photochemical efficiency?,elemental traits(leaf carbon,nitrogen,phosphorus,potassium,carbon to nitrogen ratio,l_itter carbon,nitrogen,phosphorus,potassium,carbon to nitrogen ratio)and soil traits?soil respiration rate?are significantly different among different forest types.leaf carbon to nitrogen ratio,crown area,wood density,maximum photochemical efficiency,and leaf nitrogen content have a good indicator effect on plant carbon sequestration capacity.In the potential-slight rocky desertification Bijie Salaxi research area,leaf nitrogen content and wood density can be a good indicator of vegetation carbon sequestration capacity.The leaf carbon to nitrogen ratio,crown area and _maximum photochemical efficiency in the Guanling-Zhenfeng Huajiang study area of medium-intense rocky desertification are the main indicator traits of vegetation carbon sequestration,while wood density and crown area are the main indicators of vegetation carbon sequestration in Shibing karst study area.In the future,the combination of these traits can be used to assess the carbon sequestration capacity of carbon sink tree species,and to select and evaluate carbon sink afforestation tree species.?4?This paper proposes carbon sink monitoring technology?core drilling technology,tree age prediction model establishment technology?,carbon sink tree species selection technology,forest density control and low-efficiency forest transformation technology based on plant carbon sequestration capacity and evaluates the carbon sink benefits of various forest types.Since each forest type is dominated by middle-aged forests and near-mature forests,it is at the peak of growth and development.Arbor carbon storage will continue to increase under reasonable management and cultivation,and the total carbon sink value is expected to reach 277,100 yuan to 797,400 yuan / hm².From April 2018 to November 2019,technical application demonstration verification was carried out in the three study areas.The demonstration area of Bijie Salaxi is 3.96 hm²?SLX1?and 1.21 hm²?SLX2?.The demonstration area of Guanling-Zhengfeng Huajiang is 3.71 hm²?HJ1?and 1.38 hm²?HJ2?.The dmonstration area of Shibing karst is 2.80 hm²?SB1?and 1.70 hm²?SB2?.The three demonstration sites all show a good ecological recovery trend.This research can provide technical support for the cultivation of carbon sink forestry in karst rocky desertification areas.