Agroforestry Ecosystem Structure Optimization And The Stability Improvement Strategy In The Karst Desertification Control

Agroforestry is a priority semi-natural ecosystem in fragile ecological zones.To thoroughly implement Xi Jinping thought on eco-civilization,the National Development and Reform Commission and the Ministry of Natural Resources jointly issued the Master Plan for Major Projects for the Protection and Restoration of Nationally Important Ecosystems(2021-2035),which proposes to improve the quality and stability of ecosystems comprehensively.Improving the quality and stability of the ecosystem is both a long-term problem of karst desertification(KD)control and the focus and difficulty of agroforestry ecosystem research,which is of great significance to consolidate the effectiveness of KD control and improve the service capacity of agroforestry ecosystem.Based on the methods of geography,ecology,agroforestry science,and other disciplines,combined with the theories of ecosystem structure,biodiversity,and ecosystem stability,the scientific problems such as unreasonable structure,poor stability,and unclear coupling relationship between structure and stability of agroforestry ecosystem for KD control are addressed.From 2020 to2023,three demonstration areas for KD control,including Bijie Salaxi,Zhenfeng-Guanling Huajiang,and Shibing Karst,were selected as the study areas in the Guizhou Plateau,which represents the overall ecological environment of south China of karst,and 405 soil samples were collected for determination through continuous positioning observations in three types of agroforestry test plots: homegarden(HG)、agrisilviculture(ASV)and multipurpose woodlots(MWLs).Using statistical analysis methods such as correlation and gray correlation,the study focuses on the fundamental frontier theories of agroforestry ecosystems for KD control,focusing on elucidating the structural characteristics of the system,the relationship between structure and stability,constructing a stability evaluation index system,conducting stability evaluation grading,and proposing targeted strategies for structure optimization and stability enhancement.It provides a reference basis for improving the service supply capacity of the agroforestry ecosystem for KD control,consolidating the results of KD control,and accelerating the realization of ecological product value and ecological civilization construction.(1)The species composition and diversity of agroforestry ecosystems were revealed,the structural characteristics of agroforestry ecosystems were elucidated,and the structural elements of the same type of agroforestry ecosystems in different regions KD control;were found to be highly variable.Regarding species composition and diversity,HG>MWLs>ASV.Regarding non-spatial structure(diameter,height,and canopy distribution),the overall distribution was “J”-shaped and regular to the left.Regarding spatial structure,HG and MWLs were mainly distributed in clusters,their tree species were more segregated,and the stand was more stable.Regarding spatial structure,HG and MWLs were primarily distributed in groups with high species segregation and stability.In contrast,ASV was mainly distributed randomly and uniformly,with low species segregation and poor stand stability.This reveals that structural characteristics are an important driver in stability maintenance.(2)The evaluation model of the stability of the KD agroforestry ecosystem was constructed,and the stability evaluation was graded.Based on the agroforestry structure in KD control and environmental characteristics,five primary indicators,including stand structure,species diversity,soil physical and chemical properties,microclimate,and topographic factors,were selected to construct a stability evaluation index system of mixed agroforestry ecosystem for stone desertification management.The monitoring system of its stability change characteristics was further improved.This helps to establish a long-term effective stability maintenance mechanism.(3)The main driving factors of the structure and stability of the agroforestry ecosystem for KD control were revealed,and the strategies for optimizing the design and improving the strength of the agroforestry ecosystem for KD control were proposed.After evaluating the stability of stone desertification agroforestry ecosystems and analyzing the driving factors,the stability characteristics of different types of agroforestry ecosystems for KD control are combined with the key influencing factors,the preamble theoretical basis,and the corresponding stability enhancement strategies.This helps to adjust the productivity of the local agroforestry ecosystem,strengthen the stability of agroforestry production and life,and enhance the system service function,thus promoting the overall ecosystem quality and harmony between humans and land.