| The Ansai area is located in the hinterland of the Loess Hilly and Gully Region in Northern Shaanxi,and its industrial development is deeply affected by environmental conditions.As an efficient agricultural development model,the agroforestry system can coordinate ecological construction with food supply and demand and economic growth,and is of great significance in application and promotion in areas constrained by environmental conditions.This study takes the agroforestry system in Ansai as an entry point to study the spatial pattern changes and its driving factors since its implementation of the policy of returning farmland to forest in 1999 using the technical means of combining RS and GIS,.Based on the era background of rural revitalization,the system is upgraded and optimized to provide a reference for the development of agroforestry systems in similar counties in northern Shaanxi.The study has reached the following main conclusions:(1)According to the actual survey and the summary of the existing research data,the landscape composition and configuration model types of the agroforestry system in the research area were classified and analyzed.According to the allocation ratio of agricultural and forestry landscape elements in the watershed and the characteristics of agricultural and forestry industries,the agricultural and forestry landscape allocation models at the Ansai District watershed scale are divided into"cultivated land+nursery model","orchard+X model","shed+gardening model",and"Grass+animal husbandry mode",efficient circulation mode 5 kinds.(2)Through remote sensing and Arc GIS,and using landscape ecology related theories to analyze the evolution characteristics of the living environment of the agroforestry system from 1999 to 2018,it was found that from 1999 to 2018,the cultivated land area decreased by 469.78km~2,a decrease of 58.46%;the forest land area 48.81%increase;grassland area increased by 170.85km~2,an increase of 11%;wetland area increased by 1.19km~2,an increase of 12.86%;construction land increased by 8.86km~2,an increase of 219.30%;unused land increased by 1.11km~2,an increase of 55.22%.After the arable land area has been greatly reduced during the implementation of the project of returning farmland to forests,it is necessary to optimize the quality of the arable land patches,increase the productivity per unit area,and ensure the ecological safety of the existing arable land patches.At the same time,strengthen the control of various land uses,so that the development and growth of the economy,industry and population of Ansai District can be carried within the overall environment.(3)From 1999 to 2018,woodland patches have always been in a dominant landscape position,followed by cultivated land and grassland.The patch density value(ED)of cultivated land decreased significantly,indicating a decline in landscape dominance;forest land,grassland wetland,construction land,and unused land increased significantly,indicating an increase in landscape dominance.The maximum patch area index(LPI)of cultivated land landscape decreased significantly,indicating that the dominant degree of cultivated land decreased significantly in the landscape of Ansai District,and the largest cultivated land area became significantly smaller;the landscape shape index of cultivated land,forest land,and grassland was the largest,living in The first three indicate that the overall status of these three types of land landscapes in Ansai is stable,and the internal ecosystem is relatively resistant to wetlands,construction land,and unused land;the area-weighted average fractal dimension of forest land,grassland,and construction land(FRAC?AM)The gradual increase also indicates that the shape of the landscape patches is becoming more and more complex and is not susceptible to outside interference.The increase in the contagion index(CONTAG)value indicates that the overall landscape aggregation has increased,indicating that the connectivity of dominant patches in the landscape has increased,large patches have appeared in the landscape,and various landscapes tend to Integrated development.The decline of the Shannon Diversity Index(SHDI)indicates that the degree of disturbance of human activities on the landscape has increased.Since the types of landscape types have not changed,the landscape area tends to be evenly distributed,and the overall landscape heterogeneity slightly weakens.(4)Since the country implemented the policy of returning farmland to forest in 1999,it is required to implement the conversion of farmland to forest and grassland at slopes greater than 25°.This has caused a series of changes in regional industrial characteristics and farm household production.Through field investigations and questionnaire surveys,it has been found that the evolution of the spatial pattern of the agroforestry system is driven by multiple factors such as policies,natural resource endowments,and human-driven factors.It is driven by policies such as returning farmland to forests,a series of government industrial policies,development plans,the issuance of central documents,and the“three changes”reform.It is driven by the natural endowment of slope and aspect;there are rural residents'income,the status of farmers'survival,agricultural management entities,Farmers'wishes and choices are driven by humans;these driving factors complement each other and jointly promote the evolution of the spatial pattern of the agricultural and forestry composite system in Ansai District.(5)Finally,combined with the era background and development concept of the rural revitalization strategy,from the perspective of industrial optimization,ecological construction,talent assistance,organizational upgrading,cultural creation,etc.,it proposes measures for the agricultural and forestry composite system in Ansai area to conduct a comprehensive and comprehensive Optimize and improve. |
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