| The Master Plan for the Protection and Restoration of Important National Ecosystems（2021-2035）proposed that by 2035,through vigorously implementing major projects for the protection and restoration of important ecosystems,and comprehensively strengthening ecological protection and restoration,the state of the country’s natural ecosystems such as forests,grasslands,deserts,rivers,lakes,wetlands,and oceans will fundamentally improve,the quality of ecosystems will be significantly improved,ecological service functions will be significantly enhanced,and ecological stability will be gradually enhanced.Guizhou province is the centered of South China Karst,which is the ecological barrier of the upper reaches of the Yangtze River and the Pearl River,located in the key ecological regions of the Yangtze River.Carrying out monitoring and evaluation of forest ecosystem stability is an important measure for rock desertification management to ensure ecological security of Yangtze River and Pearl River basin,and is of great significance to promote ecological protection and restoration of rock desertification areas.According to the theories of geography,restoration ecology,forest cultivation and other human-earth coordination,species coexistence theory,structure determines function,community succession,ecosystem stability,etc.,This study is aimed at the scientific issue of incomplete structure and declining function of forest ecosystem in karst rocky desertification control,diagnosed the main factors about forest ecosystem stability,constructed a stability evaluation index system,measured the stability status,and proposed the structure optimization strategy and stability enhancement strategy.We selected three typical demonstration areas of rocky desertification control,which represent the overall structure of the karst ecological environment in South China Karst,in the Guizhou Plateau（Bijie Salaxi,GuanlingZhenfeng Huajiang and Shibing Karst）.We conducted the vegetation survey and functional detection for forest ecosystem,used the correlation analysis,entropy power method,comprehensive evaluation method and gray correlation analyzes from 2019 to 2022 three years.The study is a systematic research,focused on the basic frontier research of strategies for structural optimization and stability improvement of forest ecosystems in rocky desertification control,assessed the stability of forest ecosystems,designed structure optimization strategy and stability improvement strategy.This study will provide scientific and technological references for the sustainable development of forest ecosystems.（1）The structure and function of forest ecosystems under different stone desertification management modes were found to be significantly different,and the correlation between structural and functional indicators was elucidated.In the natural state,each forest ecosystem is the most species-rich,with a wide range of tree height structure and longitudinal structure,all in a stable inverted "J" shape,with high system productivity and water-holding function,and low soil conservation function.The species richness of each forest ecosystem in the closed forestry mode,the wide distribution of tree height structure and warp structure,the stable inverted "J" shape,and the unstable "u" shape and single-peaked distribution,the system productivity and water conservation function are high,and the soil conservation function is small.The species of each forest ecosystem under the artificial afforestation model is single,the distribution of tree height structure and meridional structure is narrow,most of them have unstable single-peaked distribution,and there are faults,the productivity of the system is low,and the function of water conservation and soil conservation is high.The structure of tree height complexity,meridional complexity,Shannon-Wiener diversity index,Margalef richness index,and Pielou evenness index within the forest ecosystem showed highly significant positive correlations（p<0.01）with system productivity,water content,soil total nitrogen,and soil organic matter functions,but negative correlations with soil total phosphorus and soil total potassium,which can provide a theoretical basis for This can provide a theoretical basis for the optimization of forest ecosystem structure in rock desertification management.（2）An index system for evaluating the stability of forest ecosystem based on ecosystem structure-function-habitat-stress was proposed and evaluated,revealing that the tree and shrub forest ecosystem was in the very stable class,the shrub forest ecosystem was in the stable class,and the economic forest was in the critical state.Combining the special and sensitive characteristics of karst stone desertification areas,and considering the natural and anthropogenic factors,16 indicators such as tree height complexity,Margalef richness index,system productivity,terrain undulation and disturbance intensity were selected to construct a stability evaluation index system of forest ecosystem based on ecosystem structure-function-habitat-pressure for stone desertification management to measure the stability status,and the results showed that.The forest ecosystems of trees,shrubs and grasses in each demonstration area are in a very stable class,with high species diversity,high complexity of tree height structure and warp structure,high ecosystem function,and low stress despite poor habitat conditions.Grassland forest ecosystems are in the stable class,and grassland forest ecosystems are in the stable class,with high species diversity,high ecosystem function,good habitat conditions and low stress.The economic forest ecosystems are all in a critical state,characterized by low species diversity,narrow distribution of tree height structure and warp-level structure,and high pressure.From different management modes,the stability of forest ecosystem in natural state >closed forest > artificial afforestation.The revealing of forest ecosystem stability in different stone desertification management modes provides data support for guiding the sustainable management of forest ecosystem in stone desertification management.（3）The main factors affecting the stability of forest ecosystems in rock desertification management were identified,and structural optimization strategies and stability enhancement strategies were proposed for forest ecosystems with unreasonable structure and poor stability.The entropy weighting method and grey relational analysis showed that Margalef richness index ranked first with a weighting factor of 0.1318 among ecosystem structure indicators,system productivity ranked first with a weighting factor of 0.1382 among functional indicators,terrain relief ranked first with a weighting factor of 0.0972 among habitat indicators,and disturbance intensity ranked first with a weighting factor of0.1523 among stress indicators.Among the stress indicators,disturbance intensity ranked first with a weighting factor of 0.1523.In terms of the correlation of the indicators,the highest correlation was disturbance intensity（0.935）,followed by system productivity（0.926）,and then Margalef richness index（0.916）,indicating that disturbance intensity,system productivity and Margalef richness index are the main factors affecting the stability of forest ecosystems in stone desertification management.For forest ecosystems with unreasonable structure,structural optimization strategies such as establishing a complete thinning mechanism to improve species diversity and adopting interforest hedging are proposed to enhance the internal stability of the ecosystem;for forest ecosystems with poor stability,stability enhancement strategies such as reducing human interference and strengthening woodland management are proposed. |
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