Spatio-temporal Change Mechanism Of Farmland Landscape Pattern And Spatial Governance Design

Farmland is one of the basic terrestrial resources that support the development and survival of human beings and thus plays a crucial role in the national security of every country.During the past three decades,China's farmland resources have shown a decreasing trend of size and quality.The decreasing sizes and deteriorating quality of farmland has,in turn,begun to threaten China's food security.Pattern change is the intuitively spatial representation of the scale and quality variation of farmland.Through the characteristic development of spatial shapes as well as through changes in system structures,functions and so on,farmland landscape patterns may indicate the landscape health level.Therefore,learning more about the spatial characteristics,evolutionary processes,and function transformations of farmland can provide a reference for the comprehensive monitoring of farmland resources.Consequently,exploring the dynamic mechanisms that govern farmland change can provide the rationale for policies that aim to protect these farmland resources.Moreover,the study of farmland space management and protection based on the research above can contribute more to the coordination of land development and protectionAt present,the quantitative analysis of farmland landscape-pattern change focuses mainly on shapes,area,and dynamic-mechanisms studies at a single scale.Research on external-characteristics changes of farmland and their driving mechanisms has been done mainly on a relatively homogeneous geographical background.Less attention has been given to pattern changes brought about by changes in the structures beneath the farmland landscape,as well as to the influence of regional geographical differentiation Current basic research on farmland protection originates from the perspective of objects that need to be protected,while the mechanisms that drive farmland landscape-pattern change are largely overlooked.Currently,the coordination of farmland protection and socio-economic development has been the theme of human-environment relations.In this context,research on the mechanisms of farmland landscape-pattern change and the management and protection of farmland based on coordination between development and protection has become one of the critical scientific tasks in geography.Building upon multi-source,multi-resolution spatial,census,and field observation data,a classification system for multi-scale farmland landscape is constructed in this study,while relevant models are also developed and validated.This study addresses the technical problem of the structural decomposition of the farmland landscape Furthermore,a driving-forces analysis of farmland landscape-pattern change utilizing multi-scale and multi-scene data is attempted.The dynamic mechanisms of farmland landscape-pattern change at different time scales and spatial levels are revealed based on the results of the driving-force analysis.Finally,the structure of a spatial management system and a method of farmland protection with two boundaries and two areas are put forwardThe main points and conclusions of this study are as follows(1)Classification of farmland landscape structure in multiple scales and analysis of character change,process evolution,and function transformation of farmland landscape pattern.Currently,it is still difficult to perform positioning analyses of landscape pattern changes that reflect the landscape structure variations of farmland with an index model.Depending on a number of spatial properties such as locations and adjacency relations,distance decay,fringe effect,and on the model of patch-corridor-matrix that is applied,this study defines a type system of farmland landscape structure on the national,provincial,and city levels.According to such a definition,the classification model of farmland landscape-structure type at the pixel scale is developed and validated based on mathematical-morphology concepts and on spatial-analysis methods.Then,the laws that govern farmland landscape-pattern change in multiple scales are analyzed from the perspectives of spatial heterogeneity,spatio-temporal evolution,and function transformation.The result shows that the classification model of farmland landscape-structure type can reflect farmland landscape-pattern change and its effects on farmland production function.Moreover,farmland landscape change in different scales displayed significant disparity in zonality,both within specific regions and in urban-rural areas(2)Model construction and difference analysis of the spatio-temporal character of the dynamic mechanisms of farmland landscape-pattern change under a complicated geographic background.The dynamic mechanism of farmland landscape-pattern change is characterized by significant spatio-temporal differences under the background of regional differentiation.Therefore,it is hard to perform the quantitative analysis of the dynamic mechanisms within only a single scene and a single scale.In order to provide answers to such a question,the study designed the dynamic mechanism model of farmland landscape-pattern change with four scenarios separately containing and taking into account the individual effects of population,climate,synthesis of human and natural elements,and human factors.The differences of socio-economic conditions among east,central,and west China,local climatic differences,comprehensive differences in cultural aspects at provincial and city levels are all taken into consideration in the model construction.The result shows that the interpretation ratio of the model to farmland landscape pattern change presents a U-shaped curve,or a linear variation,in each of the different scenarios.The human-dominant scenario has the highest interpretation ratio of up to 58.87%.The specific driving factors can be concluded as land-use intensity,the scale of farmland displaced by construction projects,and the policies of land management.Additionally,the action mechanism of driving forces presents as the difference between the urbanization process and the urban-sprawl model.(3)Based on the idea of centralized management and mitigated non-agricultural interference,the study of spatial governance design of farmland is performed by developing delineation models about prime farmland conservation areas and urban-development boundaries.Aiming for the minimization of the conflict between farmland protection and urban construction,the study proposed the farmland-protection design idea characterized as farmland-centralized management that aims to minimize the non-agricultural disturbance mechanisms.Depending on such an approach to farmland protection,the research delineated the theoretical basic farmland protection area based on the single-factor layer-by-layer exclusion method,which can be summarized as "function?quality?ownership?environmental identification".Then,the theories of "elastic urban development boundary" and "rigid urban development boundary" are proposed and defined by a combination of rigid control and elastic regulation.Finally,the research puts forward a spatial protection and management strategy for farmland.It contains two boundaries and two areas:the elastic and rigid urban-development boundaries for the control of urban sprawl,the basic farmland protected area for the centralized management of farmland,and a flexible area that acts as the buffer space for farming and construction.