Method On Describing The Spatial Pattern Of Land Use And Its Application In China

The research of land use spatial pattern is the foundation of LUCC theory and practice.The depiction of land use spatial pattern is the concrete practice of land use spatial pattern theory.The research results can further improve the theory and research methods of land use spatial pattern,and improve the planning and management of land resources,which was significant for the realization of the sustainable development of economy and ecological civilization construction.The research on the method of describing the spatial pattern of land use is benificial to accurately,completely and efficiently characterize the spatial patterns and the changing characteristics of different land use types and the whole land use in China.The results can also provide scientific reference for optimizing the spatial pattern of China's land resources and dealing with global changes.At present,the connotation and research scope of the spatial pattern of land use is not clear,and the study on the spatial pattern of land use has not formed a complete theoretical system,which leads to the incomplete characterization of the spatial pattern of land use.In addition,the large number of pattern indexes and the correlation between different indexes could easily lead to the redundancy of land use patterns depiction.Based on the deep understanding of the connotation of spatial pattern of land use,this paper constructed a conceptual model of land use spatial pattern depiction that conforms to the characteristics of land use and a set of pattern index with relative independence and comprehensiveness.By using fuzzy C-means algorithm(FCM)clustering method,the paper established the relationship between indicators and spatial patterns and characterized the spatial pattern and dynamics of individual type and overall land use in China.The main results of this paper are as follows:(1)Based on the current domestic and international research about the theories,contents and methods of land use spatial pattern,the paper deeply analyzed the influencing factors and scales of spatial pattern and the relationships between them.The spatial pattern of land use is defined as the allocation of the land use elements at a certain temporal spatial scale.This paper focused on the geometric features(area,shape and distribution)and type features(structure and diversity)and built the conceptual model from the Time-Space-Type three scales.The conceptual model of "geometric and types features" three-dimensional land use spatial pattern could reasonably,objectively and scientifically reflect the factors that characterize the spatial pattern of land use and the interaction between them.(2)On the basis of the conceptual model of land use spatial pattern,this paper constructed a set of methods to describe the spatial pattern of land use.First,based on the factor selection principles of science,relative independence,rationality of spatial-temporal scale,comprehensiveness and conciseness,representive indexes were selected from two perspectives of individual types and the whole land use.The indexes of class area,area-weighted mean patch fractal dimension and area-weighted mean nearest neighbor distance are selected as the representative index of individual land use spatial pattern.Similarly,area-weighted mean patch size,area-weighted mean patch fractal dimension and area-weighted mean nearest neighbor distance,structural index and richness index were selected as the representive indexes of the whole land use spatial pattern.Then,the feature scale of the individual type and the overall land use was determined using grid area filling method.At last,FCM clustering method was introduced to extract different spatial patterns.With the division index F,the fuzzifier m was determined to be 2 and the number of land use spatial patterns divisions was determined to be five.Through the FCM clustering curve,the quantitative relationship between index and spatial patterns of different geometrical features was calculated.Finally,a land use spatial pattern description method was established with three steps of index selection,feature scale determination and FCM clustering.(3)The spatial patterns of the individual land use type in 2010 China were studied.The spatial patterns of cropland,forest,grassland and unused land were similar.The five types of spatial patterns were named as full pattern,fractal pattern,complex shape and small area pattern,simple shape and small area pattern and scattered pattern.By contrast,the spatial patterns of waterbodies and built-up land were similar.The five types of spatial patterns were named as full pattern,fractal and small area pattern,complex shape and small area pattern,simple shape and small area pattern and scattered pattern.According to the division equation,the characteristics of five spatial patterns and thier spatial distribution of each land use type were summarized.The full pattern of cropland was mainly distributed in the Northeast Plain,North China Plain,and Sichuan Basin.The fractal pattern was mainly distributed in hilly areas.These two kinds of spatial patterns were the main farming agricultural areas in China.The spatial pattern of forest in China showed a characteristic that the area gradually becomes smaller and the shape gradually becomes simpler from southeast to northwest.The spatial pattern of grassland had obvious spatial agglomeration feature,showing a northeast-southwest strip distribution.Its full pattern was mainly distributed in the northern part of Inner Mongolia pastoral area and the western part of Tibetan pastoral area.Due to the small area and scattered distribution of waterbodies,its spatial pattern did not show a large area of agglomeration phenomenon.The full pattern of built-up land was mainly distributed in the city densely-distributed areas of the Beijing-Tianjin-Hebei region,the Yangtze River Delta region,and the Pearl River Delta region;the fractal and small area pattern was mainly represented as the densely distributed rural residential land.The spatial pattern changing from simple and small area pattern to fractal and small area pattern of built-up land reflected the shape of the built-up land getting more complicated in the process of its expansion,and the development from fractal and small area pattern to full pattern is a relatively mature stage of built-up land development.The spatial pattern of unused land showed an apparent gradual changing feature of from the southeast(scattered pattern)to the northwest(full pattern).Comparing the spatial patterns of different types of land use,it was found that the spatial pattern of cropland and forest showed spatial complementarity,and the spatial pattern of grassland and unused land showed spatial correlation.(4)For the whole land use in 2010 China,the spatial pattern was characterized by its geometric features,structure and diversity.First,the geometric features were clustered into five categories,which are named as simple and large patch pattern,complex and large patch pattern,complex and small patch pattern,simple and small patch pattern and scattered pattern.The simple and large patch pattern was mainly grassland and unused land in the northwestern region,and mainly woodland in the southern Tibet and Changbai Mountain and Xiaoxing'anling in the northeast.The complex and large patch pattern reflected a combination of a main land use type and some minor land use types.The complex and small patch pattern was the most important type in the spatial pattern of geometric features,reflecting a more balanced combination of multiple types of land use types.The main cause of the complex shape was the topographic factor with apparent clusters in hilly areas.Simple and small patch pattern had various compositions.The land use patches were small due to the cutting of mountains and rivers,and the shape was simple.The scattered pattern indicated a type of land use type was isolated by some other land use types.Second,there were 61 different types of structures in China's land use in 2010,but there were only 14 main types of structures that account for 90%of the cumulative total.Among them,the grassland-unused land structure had the largest number of grids,followed by the unused land structure,cropland-forest structure,and grassland structure.The spatial distribution of structural features showed obvious spatial agglomeration and was significantly affected by natural factors such as terrain.Thirdly,the characteristics of China's land use diversity were generally high in the northeast and the southeast,and low in the northwest.The northeast and southeast regions had rich land use types due to various climate,topography and human activities.By contrast,the land use diversity was low in the northwest with mainly grassland and unused land due to terrain and climate constraints.(5)The changes of the spatial patterns of land use in China from the late 1980s to 2010 were analyzed,including cropland,forest,grassland,waterbodies,built-up land,unused land and the whole land use.The spatial distribution and quantitative features of the major dynamic types of the land use patterns were further analyzed.The results showed that the built-up land has the highest degree of dynamics and a rapid increasing trend,followed by waterbodies.While the dynamics of cropland,grassland and unused land are all around 20%.Forest had the lowest dynamic degree at 11.69%.During the study period,all 30 spatial patterns of cropland,waterbodies,and built-up land were occurred.By contrast,there were only 10 pattern changes of forest and 14 pattern changes of unused land.The dynamic degree of the whole land use was about 20%.In the dynamics of geometric features,the dynamics of the increasing average patch area were mainly distributed in Xinjiang,and the dynamics of decreasing average patch area were mainly distributed in the northern Daxing'anling,the Yangtze River Delta,and the North China Plain.The dynamics of increasing shape complexity were mainly distributed distributed in the northern Daxing'anling,Xiaoxing'anling,Yunnan plateau,and Xinjiang.The dynamics of decreasing shape complexity were mainly distributed in the southern Daxinganling,the south of the Northeast Plain,and the Pearl River Delta.The most important structural dynamics are the conversion between grassland,unused land and their combainations,which mainly occured in the northwest region.The main new types in the structure changes are unutilized land and built-up land.The increased unused land was distributed in the central and northern parts of the Daxing'anling and Xinjiang.The increased built-up land was mainly in the North China Plain,Shandong hills,the middle and lower reaches of the Yangtze River,and the southeast coastal areas.The main reduction type in the structural changes was grassland,mainly distributed in the northern part of Daxing'anling,Shandong hills and Xinjiang.The dynamic range of diversity is small and dominated by increased diversity,mainly distributed in the northeastern region,Xinjiang,Hebei Plain,the north of Southeast Hills,and Central Mountain Range in Taiwan.The dynamic changes of decreasing diversity were mainly distributed in the northwestern plains of Shandong,Shandong hills,the Pearl River Delta,Alxa Plateau and Xinjiang.The results indicate that there are three problems in the evolution of China's land use spatial pattern.First,the cropland with good quality in the east and the south of China decreased and became more fragmented.The quality of new cultivated land in the north and west was not so good as the original cropland and its environmental impacts need to be further estimated.Second,grassland degradation in the northwest threatened the local ecological environment.Third,built-up land expansion caused the loss of cultivated land and problems of the local environment.It is necessary to carry out corresponding optimization and adjustment,adhere to basic farmland protection policies,increase grassland construction and protection,and adjust the built-up land developing model.The main innovations of this study are as follows:(1)A conceptual model based on geometric features and type features of time-space-type three-dimensional land use spatial pattern is constructed.The model clarifies the research scope and scale of spatial pattern of land use.The model can not only apply to depicting the geometric features for individual types of land use,but also the geometric features and the type features for the whole land use.The model has wide application and a good perspective of promotion in different areas.(2)Under the theoretical framework of the conceptual model,a system of methods to describe the spatial patterns for different land use types and the whole land use is proposed from the index selection,scale selection and clustering analysis.The methods can reasonably and scientificly depict the spatial pattern of land use.(3)This paper comprehensively describes spatial patterns of the different types of land use and the whole land use in China from various angles and perspectives.In addition,the dynamics of the spatial patterns for individual land use types and the whole land use were depicted successfully.The results of the spatial pattern of land use in China further confirm dialectical unity relationship of the independence and correlation of the geometric features and type features,the similiarity and difference between the individual type of land use and the whole land use,and the interaction between spatial and temporal dimensions.