Cultivated land fragmentation and its influencing factors in karst mountainous areas from the perspective of geomorphic differentiation

DUAN Yujie; ZHAO Yuluan; ZHOU Chunfang

doi:10.11932/karst20250608

Abstract：The fragmentation of cultivated land,as a land use pattern contrasting with large-scale farming operations,constrains agricultural modernisation and sustainable development.This is particularly pronounced in the karst mountainous regions of southwestern China,where factors such as the fundamental agricultural conditions of large population and limited land,the egalitrian allocation method of matching fertile and infertile plots,combining with distant and nearby plots,and the complex natural environment dominated by mountainous terrain have led to a marked pattern of cultivated land fragmentation.Consequently,targeted research holds significant importance for ensuring food security and achieving cultivated land comprehensive governance in karst mountainous areas. The Qixingguan District,situated in northwestern Guizhou Province,exhibits a topography that slopes from southwest to northeast in a terraced descent.The terrain is complex,characterised by extensive mountainous hills and limited plains or basins,with karst landforms such as peak clusters and trough valleys developed throughout.The region's geology is dominated by carbonate rocks and basalt,with pronounced rock desertification,making it a quintessential example of China's ecologically fragile karst areas in the southwest.Furthermore,the spatial distribution of cultivated land presents the characteristics of scattered,small,and fragmented,with sharp contradictions between people and land,providing an ideal case area for the study of cultivated land fragmentation.This study employs 37 townships and sub-districts,encompassing 477 administrative villages within Qixingguan District,as its research units.Drawing upon data from the Third National Land Survey,rural land contract management rights,and farm household surveys datas,it aims to systematically reveal the characteristics,patterns and spatial correlations of cultivated fragmentation across different landform types,accurately identify the key influencing factors and their respective intensities,and thereby provide a scientific basis for the comprehensive governance of cultivated land fragmentation in karst mountainous areas. The research methodology primarily comprises,(1)Delineating landform types within the study area by integrating regional topographic characteristics and relevant classification standards;(2)Constructing an evaluation index system for cultivated land fragmentation from dual perspectives of landscape and ownership to comprehensively characterise fragmentation status;(3)Employing spatial autocorrelation analysis to reveal the spatial distribution patterns and correlation characteristics of cultivated land fragmentation;(4)Utilising multiple linear regression models and geographic detector models to quantify the intensity of influence and regional variations of each factor on landscape fragmentation and ownership fragmentation. The research findings indicate,(1)The landforms of Qixingguan District can be categorised into four types:low mountain valley slopes,medium mountain hilly terraces,medium mountain valley terraces,and medium mountain hilly slopes.The number of administrative villages covered by each landform type is 49,162,81,and 185,respectively;(2)Qixingguan District exhibits high levels of cultivated land fragmentation,with ownership fragmentation exceeding landscape fragmentation.Distinct high-value and low-value zones are discernible.Administrative villages in medium-mountain valley slopes and medium-mountain hilly slopes demonstrate stronger cultivated land resource scale and spatial aggregation,while those in low-mountain river valley slopes and medium-mountain hilly slopes exhibit greater operational intensity;(3)The spatial distribution of cultivated land fragmentation in Qixingguan District exhibits correlations,with distinct combinations of topographic features:low mountain river valley slopes show high landscape fragmentation and low ownership fragmentation;medium mountain valley slopes exhibit high ownership fragmentation and low landscape fragmentation;medium mountain upland terraces demonstrate high levels of both landscape and ownership fragmentation;while medium mountain upland slopes display relatively low levels of both;(4)Landscape fragmentation is primarily influenced by the proportion of construction land,elevation,and terrain dissection.Specifically:low mountain river valley slopes and medium mountain hilly slopes show positive correlations with slope gradient;medium mountain slope valleys correlate positively with terrain dissection;while medium mountain hilly terraces are driven by the proportion of construction land.The key drivers of ownership fragmentation are the proportion of construction land and rural population density.Among these,rural population density is the core driver for low mountain river valley slopes,medium mountain slope valleys,and medium mountain hilly slopes,while medium mountain terraced land primarily exhibits a positive correlation with per capita cultivated land area. Based on the distinctive characteristics of cultivated land resources across different topographic zones,this study proposes a comprehensive approach to cultivated land resource goverance encompassing landscape,land tenure,and land use practices.This framework provides scientific support for optimising cultivated land distribution,advancing land transfer and consolidation,and enhancing agricultural scale in Qixingguan District and karst mountainous areas of Southwest China.It holds significant practical value for safeguarding regional food security and propelling agricultural modernisation.