Current Research Situations, Problems and Recommendations of Land Use Structure and Layout Optimization

Yuting DONG, Zisheng YANG

Institute of Land & Resources and Sustainable Development, Yunnan University of Finance and Economics, Kunming 650221, China

Abstract Land is the foundation for human survival and development, and all human social and economic activities are inseparable from the land as a space carrier. With the continuous development of China’s social economy, China is facing new social development needs such as urban-rural integration and rural revitalization. At the same time, China starts to attach great importance to ecology and has proposed the concept that lucid waters and lush mountains are invaluable assets. In this situation, the rational use of land resources, the optimization of land use structure and layout are also facing new challenges and problems, and more comprehensive consideration is required to make relevant optimization. Using the method of literature comparative analysis, from the conceptual connotation, basic theory, method model, and specific practice of land use structure and layout optimization, this paper analyzed and summarized the current research situations and problems, and finally came up with recommendations for the future research.

Key words Land use structure optimization, Layout optimization, Current research situations, Problems and recommendations, Literature comparative analysis

1 Introduction

Land is a most essential natural resource. As the basis of production in various industries and human life, land plays a very important fundamental and strategic role in the development of human society[1]. "Constant improvement of sustainable development ability" is a goal of comprehensively building a well-off society[2]. The sustainable use of land resources is an important link to achieve sustainable development[3]. China’s sustainable development capacity is directly related to the rational use of land resources. With the rapid development of social economy, the demand for land in various industries is also increasing. The demand for development is unlimited, but the land resources are limited. As China proposes urban-rural integration, rural revitalization strategies and national land spatial planning, natural resources are facing continuous integration and land use is becoming more and more complex. It is necessary to comprehensively consider multiple aspects and rational use of land resources based on ecological, economic and social goals. The rational development, utilization, protection, consolidation and management of land resources are of great practical significance to China’s economic and social development[4]. Therefore, how to make the land resources reach a rational and sustainable use to meet the current development demands is very important. The optimization of land use structure and layout can maximize the regional comprehensive benefits[5], that is, ecological, economic, and social comprehensive benefits obtain the best results while laying a solid foundation for sustainable development. In order to obtain a deeper understanding of the current research situations and development trends of land use structure and layout optimization, we studied the conceptual connotation, basic theory, method model, and specific practice of land use structure and layout optimization. On this basis, we analyzed existing problems and finally came up with some pertinent recommendations.

2 Current research situations of land use structure and layout optimization

2.1 Connotation

2.1.1Optimization of land use structure. Niel Plummer defined the optimization of land use structure in 1993: the optimization of land use structure is to make more reasonable quantity and spatial layout arrangements for various types of land resources in the area according to the characteristics of land resources and land suitability evaluation, to achieve certain social, ecological and economic optimal goals, improve the efficiency and benefits of land use, maintain the relative balance of the land ecosystem, and accordingly realize the sustainable use of land resources[6]. Some Chinese scholars also defined the optimization of land use structure. In the opinion of Liu Yansui, the optimization of land use structure is to make more reasonable arrangements for different land use types in the region according to the characteristics of land resources, to achieve a certain optimal land use goal, so as to improve the efficiency and benefits of land use and maintain relative balance of the land ecosystem and realize sustainable use of land resources[1]. Yan Jinming believed that the optimization of land use structure is the expectation and goal for the unreasonable land use situation. Land use structure configuration is a process and means, its purpose is to match a certain land use method with the suitability of the land and the economics of society, so as to form a reasonable land use structure and maximize the comprehensive land benefits[7]. As stated by Li Xin, based on comparative advantage theory, under certain constraints, land use structure optimization is to allocate land resources to higher-efficiency land-use departments to improve the overall benefit of land use, and its essence is the resource allocation in economics, that is, the allocation of regional land resources to different land use departments on the principle of maximum benefit[8]. From the above references, it can be seen that the optimization of land use structure is to make reasonable arrangements of land use in a certain region under certain constraints, usually the characteristics of the land itself, to improve land use benefits and functions and to achieve the sustainable use of land resources.

2.1.2Optimization of land use layout. In foreign countries, the methods of land use optimization appeared in the early 20th century. Until the middle of the 20th century, the relevant research still remained at the early stage[9]. In the 1980s, with the promulgation of relevant documents such as theOverallLandUsePlanand the development of geographic information system (GIS) technology, China has also started a more in-depth study on the optimization of land use layout[10]. Cai Yumei contended that land use layout is the spatial configuration of land use structure and it is the key to the implementation of land use planning[11]. In the opinion of Xu Yueqing, the optimization of spatial allocation of land use can also be called the optimization of layout of land use space, it is a systematic arrangement, design, combination and layout of the land use structure and direction in the region on the spatial and temporal scale according to specific planning objectives and relying on certain technical means, to obtain multi-object, multi-level, multi-category land use space allocation plan composed of points, lines, areas, and networks. It is a process of comprehensively comparing the economic, social and ecological benefits of the land space allocation plan and finally determines the optimal plan for the target benefit[12]. Li Xin stated that land use layout optimization means that the planner spatially rearranges various land resources to increase the comprehensive benefits of land use. The basic criterion for layout optimization is space suitability, that is, to allocate various land resources to more suitable space units. Its goals include not only economic, ecological, and social benefits, but also space goals, such as compactness of spatial distribution, and compatibility,etc.[8]. From the above references, it can be concluded that the optimization of land use layout is a process of specific and reasonable allocation of spatial structure in accordance with certain standards and certain methods of land resources in a certain area, so as to achieve a specific goal of improving land use efficiency.

In general, many scholars have explained their concepts and connotations in terms of the nature and objectives, processes and methods, status and functions of land use structure optimization and land use layout optimization. The land use structure optimization is to allocate a reasonable amount of land resources, to achieve a certain optimal land use benefit. The land use layout optimization is mainly to implement the optimized land use structure in space through a certain method on the basis of reasonable optimization of the amount of land resources.

2.2 Basic theoriesThe land use structure and layout optimization is the core of land use planning, and its research is based on the basic theory of land use planning. In 1973, Dutch professor Faludi summarized it as planning theory and in-planning theory. The former mainly refers to social positioning and procedural planning parts, such as a compromised mixed model and a rational model; the latter mainly refers to specific work planning parts, such as urban location theory and industrial location theory[13]. Some Chinese scholars also proposed their opinions. Yang Zisheng believed that the spatial allocation of the land use structure should be optimized according to the land ecological suitability theory, ecological economic benefit theory, landscape heterogeneity and diversity theory[14-15]. Ou Minghao stated that the basic theory of land use planning should include system theory, control system, location theory, prediction theory and sustainable development theory[16]. In the opinion of Cai Yumei, land use planning theory can be divided into three levels (basic theory of economics, overall theory, and subject theory), such as location theory, system theory, sustainable development theory, environmental impact assessment theory,etc.[17]. Wang Wanmao held that land use planning theory should include land rent price theory, land location theory, ecological economic theory, sustainable use theory, human-land coordination theory and systems engineering theory[18]. Theories studied by scholars are mainly land ecological suitability theory, ecological economic benefit theory, location theory, sustainable development theory, system theory,etc.

2.2.1Land ecological suitability theory. The land ecological suitability is referred to as land suitability[15]. Land suitability refers to the applicability of specific land types to specific land uses[19]. Generally, cooperation with nature is more effective than confrontation with nature[20]. Since entry to the 20th century, China’s urbanization process has accelerated. Due to the rapid pursuit of economic development and the neglect of ecological rules, it has caused some unreasonable land use problems, making land ecological problems more serious. Therefore, when conducting land use layout, we must respect nature and optimize the land use layout according to the land suitability.

2.2.2Ecological economic benefit theory. According to the ecological economic benefit theory, the services generated by the ecological transformation process of any ecosystem have an important role in the life support system of the earth, and this role is also the most fundamental element for the sustainable development of human society, economy and environment[21]. The land use takes the ecological environment as the basis, the economic benefits as the core and ultimate social benefits as the foothold[15]. At the same time, land use is restricted by the rules of nature, economy and ecology. Therefore, it is necessary to consider the ecological and economic benefit theory, and make reasonable land use with the goal of maximizing the comprehensive benefits of ecology, economy, and society.

2.2.3Location theory. Location refers to the space and place occupied by something[22]. Location theory is the foundation of regional science, and is the combination theory of studying the spatial selection of economic behavior and the economic activities in the space[23-24]. Location theory is also a theory to study how to select the location of human economic space and how to optimize the combination of human economic activities in space, and it is an effective method to solve space economic problems[24-25]. Therefore, location theory can guide the optimization of land use structure and layout, and also lay a theoretical foundation for land location theory.

2.2.4Sustainable development theory. The United Nations Environment Program proposed that "protecting the natural environment is an essential condition for sustainable development"[26]. The World Commission on Environment and Development believes that sustainable development refers to development that can meet the needs of contemporary people but not harming the ability of future generations to meet their needs[27]. Its basic characteristics are fairness, sustainability and commonality[28]. Its main content is ecological, economic and social sustainability[29]. The Food and Agriculture Organization of the United Nations (FAO) has put forward five principles for the sustainable use of land, namely, productivity, safety, protection, feasibility, and acceptability[30]. The rational use of land resources will definitely contribute to the sustainable use of land resources, which is also the foundation of social and economic development, both have the same connotation and goals[31-32]. Therefore, it is necessary to apply sustainable development theory to the land use structure and layout optimization.

2.2.5System theory. System is an organic whole with a certain function. It is generally believed that it is composed of two or more basic elements that depend on each other and coexist[33]. From the perspective of system theory, land use is to treat land as a system, to analyze the structure and function, to study the interrelationship among related elements, and to use system theory to achieve the purpose of land use optimization[34-35]. Land use involves many factors such as resources, environment, society, economy, ecology,etc., and these factors interact with each other. The change of any one of these factors will lead to changes in the overall land system. Therefore, system theory needs to be applied to guide land use optimization.

The basic theory of land use planning is the basis for the land use structure and layout optimization. Scholars present their views from different levels. There are mainly general macro levels, such as: system theory, control theory, prediction theory,etc.; and a specific level, such as: land ecological suitability theory, ecological economic benefit theory, cultivated land protection theory,etc. With the deepening of research, the fundamental role of the theory becomes more and more important. Besides, due to the development of the times, the emergence of new ideas and new demands, the basic theories related to land use planning will be further enriched.

2.3 Methods and modelsThe focus of land use structure optimization is to allocate the land resources in the area in accordance with different goals. The land use layout emphasizes the space allocation based on the suitability or development potential based on the quantity target of land resources[36]. Strictly speaking, the land use layout optimization is also part of the land use structure optimization. Based on the original empirical method, Juren applied the principles and methods of ecology and system science, and proposed a way to build mosaic patterns on the comprehensive land use allocation[37]. Li Xia first used neural network, ant colony algorithm and improved shortest distance method to obtain the cellular automaton conversion rules, and optimized the urban land layout simulation[38]. Using the system dynamics principle, He Chunyang established the SD model of regional land use situation change, and simulated the regional land use structure change in different situations[39]. Tang Jianglong predicted the land demand with the aid of artificial neural network and optimized the land use structure[40]. In the opinion of Kong Wei, the most basic method of land use structure optimization is the linear programming method commonly used in resource optimization[41]. Using ant colony algorithm, Gao Xiaoyong solved the structural condition of regional land use in the constrained space when the land use spatial agglomeration was the highest and planning cost was the smallest[42]. Zhang Honghui believes that multi-objective optimization of land use is an inevitable choice[43]. Wang Liping held that the gray model is an important method for predicting the relevant parameters of land use[44]. Li Jianlong constructed an optimization model of land use structure based on ecological green equivalents, to improve land use efficiency[45]. Cao Shuaietal. coupled the MOP with GeoSOS-FLUS models to carry out composite optimization of land use structure and layout[36]. To optimize the land use layout, Liu Yaolin introduced the ecosystem service value and the space compactness of construction land into the optimization model[46]. Based on the ecological constraints and natural suitability of land development, Dilishati Yakufuetal. clarified the development direction and layout of land space development and construction[47]. Some scholars employed the Markov method to predict the land use structure, the basic principle is to use the current value and transition probability to predict the future value[48]. At present, there are mainly the following research methods and models for land use structure and layout optimization.

2.3.1Suitability evaluation of land space development and construction. The land space development suitability is determined by the resource and environmental carrying capacity of a certain geographical space, the foundation and potential of economic development, and the suitability degree of carrying urbanization and industrialization development[49-50]. Land space development and construction suitability can be divided into land space development suitability and construction land suitability, and basic concept of both originates from land suitability concept[49].SeveralOpinionsoftheCentralCommitteeoftheCPCCentralCommitteeandtheStateCouncilontheEstablishmentandSupervisionoftheLandSpacePlanningSystemissued in May 2019 states that it is required to coordinate the layout of functional spaces such as ecology, agriculture, and towns in a scientific and orderly manner, and delimit the spatial control boundaries such as the ecological protection red line, permanent capital farmland, and urban development boundaries based on the evaluation of the carrying capacity of resources and environment and the land space development[51]. The land space development and construction suitability is the basis for protecting the land ecological space, rationally arranging construction space, and optimizing the land space development pattern and structure[50].

2.3.2Ecological green equivalent. The proposal of green equivalent starts with the proposal of urban green space. In the United States, green equivalent is the area in the city where the natural landscape is maintained, or the area where the natural landscape is restored[52]. The ecological green equivalent is derived from taking the forest ecosystem as a measure[45]. The ecological green equivalent is the ratio of the green amount of various green plants to the green amount of the same amount of forest area[53]. With the acceleration of the urbanization process in China, new urbanization requires land use and optimization under certain ecological standards. Ecological green equivalent is a dynamic evaluation method and it can effectively evaluate the ecological environment quality of the land in the study area[54].

2.3.3Multi-objective planning. When society is transitioning to a post-industrial society, land use planning sets forth that land use should continuously improve its use efficiency, and at the same time of achieving economic benefits, it should pay attention to improving both social and ecological benefits[55-56]. Multi-objective planning means to make some objectives under some given finite and to sequential goals and to achieve these objectives under limited conditions, with the smallest deviation from the overall goal[57]. Because the multi-objective coordinated development needs to be achieved in the process of land use structure and layout optimization, it is very important to apply the multi-objective planning.

2.3.4Ecosystem service value. Ecosystem services refer to life support products and services obtained directly or indirectly through the structure, process, and function of the ecosystem[58]. It includes both tangible materials and intangible services, and its service types mainly include supply services, adjustment services, support services and cultural function services[59]. Ecosystem service value refers to the direct or indirect benefits people obtain from the ecosystem. Taking the ecosystem service value as the standard, the ecosystem service value in a certain area can be calculated to integrate the ecosystem service value into the land use planning, so as to realize the optimization and sustainable development of land use structure in the area.

2.3.5Cellular automata model. The cellular automaton model (CA model) is a spatio-temporal dynamic model formed by a series of model construction rules. Different from the general dynamic model, it is not realized by equations or functions, and has distinct spatio-temporal coupling characteristics, and it is good choice for complex land-use system[60]. However, the cellular automaton (or automata) model also has limitations. Based on raster images, despite full consideration of the interaction between grids, it is still susceptible to the influence of adjacent grids, and only can spatially stimulate a single land type, and can not optimize its spatial layout, and it lacks subjective factors, thus later scholars attempted to build a composite model to solve this problem[61-63].

Diversified methods and models provide diversified methods for land use structure and layout optimization. Using different methods and models, it is able to get optimization results with different emphasis. In recent years, with the deepening of the research, the method has become more and more inclined from quantitative analysis to quantitative analysis. In addition, due to the scarcity of land resources and the requirements of environmental protection, its goals are also increasingly inclined to compound optimization and sustainable development, maximizing comprehensive benefits, rather than focusing on quantity optimization or maximization of economic benefits in the past. Therefore, in recent years, the application of methods and models in land use structure and layout optimization has become gradually changed to achieve these goals.

2.4 Specific practice

2.4.1Specific practice of land use structure optimization. In the 1950s, most of the foreign studies used the soil suitability method and the comprehensive balance method to optimize the regional land use structure, while the relevant domestic studies started relatively late[64-65]. In the 1970s, most of the domestic and foreign studies on the land use structure optimization used linear programming (LP) modeling method. Chamesetal. applied linear programming technique to land use planning[66]. In China, Chen Guoliangetal. first used linear programming method to study the rational eco-economic structure model of agriculture, forestry and animal husbandry in the Loess Hilly Region of Guyuan County, Ningxia[67]. With the development of the times and technology, some new methods and models have appeared to optimize the land use structure. Using the system dynamics model, Zhao Xiaomin adjusted relevant parameters, and proposed five land use structure plans under different social and economic conditions in Hangzhou[68]. With the aid of Markov method, Liu Qiong predicted the land use structure of Kunshan City, Jiangsu Province[69]. Gong Jianzhouetal. studied multi-objective optimal allocation of ecological and economic benefits-natural ecological benefits oriented to the land use structure in Guangzhou[70]. Martin Banse simulated the land use change in Europe with the aid of CLUE-S model[71]. Cao Shuaietal. optimized the land use structure in Jintan District, Jiangsu Province through a multi-objective planning model[36]. From the ecological green equivalent perspective, Xu Jieetal. analyzed the land use structure in Hohhot[53].

2.4.2Specific practice of land use layout optimization. In the 1950s, most developed countries such as the United States and the United Kingdom used the empirical planning optimization method to optimize the land use space layout, but due to high subjectivity, this method made the land use efficiency in this period relatively low[72]. After the 1990s, with the development of computer technology and geographic information technology (GIS), remote sensing system (RS), global positioning system (GPS) and other geographic information technologies, these technologies began to be gradually applied to the land use space layout optimization. Verfuraetal. constructed different functional areas using integrated land use system based on GIS and RS in a US state[73]. Churieccetal. optimized land use structure layout in Spain using GIS and linear programming method[74-76]. Taking the suburbs of Yan’an City as the research area, using GIS overlay and spatial analysis, Pang Shaetal. obtained the sensitivity evaluation results, combined with the landscape analysis, and divided the research area into 4 areas[77]. Taking Huairou Reservoir in Beijing mountainous area as the research object, based on ecological service value theory, grey parameter linear programming theory and CLUE-S model, Zhao Yang conducted spatial optimization of land use[78]. In view of the special features of mountain town construction, Yang Zisheng established a set of evaluation indicator system and used GIS technology for evaluation, and his evaluation results provided a basis for the adjustment and optimization of land use layout in Dehong, Yunnan Province[79]. Using GIS methods, Wang Qietal. classified the land use ecological suitability in Zanhuang County, Hebei Province, and realized the research of layout and structure optimization[80].

In recent years, with the deepening of research and technological development, many more regions have started to focus on the optimization of land use structure and layout, and have achieved certain results, which effectively promotes the sustainable and rational use of land resources. By comparison, the domestic research on the optimization of land use structure and layout started later. Besides, in the practice of land use structure optimization, domestic scholars have made more achievements, but in terms of land use layout optimization, further efforts are still needed.

3 Problems in the research of land use structure and layout optimization

3.1 Both content and system of land use structure and layout optimization to be further improvedCompared with foreign countries, the domestic research on the optimization land use structure started later, the research on land use layout optimization is particularly later. Besides, the further development of China’s social economy has created further demand for land and space. The Land Space Planning proposes that optimizing the national land spatial structure and layout requires adherence to land-sea integration, regional coordination, and urban-rural integration[51], which makes land use structure and layout optimization face new challenges. Therefore, both content and system of land use structure and layout optimization need to be further improved.

3.2 Objectives of land use structure and layout optimization to be further adjustedMost previous researches on the optimization of land use structure and layout focused on the realization of the economic objective or a specific objective. Due to the increasingly prominent problems of land resources and ecological environment in China, as well as the increasing emphasis on ecology at the national level, the concept that lucid waters and lush mountains are invaluable assets, ecological priority, and green development, the objectives of land use structure and layout optimization also need to be adjusted to meet the new needs of social development, so as to achieve the common and sustainable development of ecology, economy and society.

3.3 Methods and models for land use structure and layout optimization to be further studiedAt present, natural resources are facing challenges of continuous integration, and the increasingly complex land use structure[36].SeveralOpinionsoftheCentralCommitteeoftheCPCCentralCommitteeandtheStateCouncilontheEstablishmentandSupervisionoftheLandSpacePlanningSystemissued in November 2019 states that it is required to coordinate the layout of functional spaces such as ecology, agriculture, and towns in a scientific and orderly manner, and delimit the spatial control boundaries such as the ecological protection red line, permanent capital farmland, and urban development boundaries based on the evaluation of the carrying capacity of resources and environment and the land space development[81]. This imposes new requirements for the selection of land use structure and layout optimization methods and models, so relevant research needs to be strengthened to meet the allocation demands.

3.4 Inadequate empirical research on small scale of land use structure and layout optimizationChina is vast, and there are distinct natural and economic differences between different regions. At present, the domestic empirical research on the land use structure and layout optimization has made certain achievements, but most of studies are concentrated at the city and county level, and the small-scale empirical research at the village level is relatively inadequate[82]. The "implementation of rural revitalization strategy"[83]proposed by the 19th National Congress of the Communist Party of China, as well as the development requirements of "urban-rural integration" and "lucid waters and lush mountains are invaluable assets" in the new period, have increasingly manifested China’s emphasis on rural areas and the current need for small-scale empirical research.

4 Recommendations

4.1 Sustainable land useSustainable development is an objective of land use structure optimization, and it is also a requirement of the development of the times.OpinionsoftheCentralCommitteeoftheCommunistPartyofChinaontheImplementationoftheRuralRevitalizationStrategyissued in February 2018 stated that it is required to build rural areas with thriving businesses, pleasant living environments, social etiquette and civility, effective governance, and prosperity[84], which is consistent with the concept of sustainable land use to a certain extent. Therefore, in the process of urban-rural integration, it is recommended to comprehensively consider the issue of sustainable land use and strengthen research on sustainable land use to improve the science of land use structure and layout optimization in a sustainable context.

4.2 Multi-objective and diversified optimization of land use structure and layoutIn the past, land use optimization mainly focused on the improvement of economic benefits or a certain functional benefit. At present, the coordinated development of ecology, economy, and society is the theme of land use. It is recommended to take comprehensive consideration of ecological, economic and social goals, which has a positive effect on improving the land use structure and layout optimization. At the same time, the diversified land use methods are of great significance to the sustainable ecological, economic and social development[85]. Multi-objective and diversified optimization can achieve the coordinated development of land use and ecological protection while improving economic efficiency, promoting a balanced layout of space, and also improving the applicability of final optimization. Therefore, it is recommended to strengthen its research, so as to better achieve coordinated development.

4.3 Methods and models for land use structure and layout optimizationDifferent regions have different development conditions and constraints, and different land requirements. With the shrinking of land resources, urban and rural land use becomes more and more complicated. Government has also put forward new policies and development requirements such as ecological civilization and rural revitalization. Simply adopting the traditional, single land use structure and layout optimization method or model can no longer effectively meet the needs of the rational use of regional land. Therefore, in the context of new requirements in the new period, it is necessary to study new methods and models or compound models, and introduce new constraints and control conditions to optimize, so as to achieve the rational use of land resources.

4.4 Empirical research on small scale land use structure and layout optimization at village levelThe empirical research on small scale of land use structure and layout optimization at village level is still very few. The development of rural areas is a strategic requirement of China in the future.OpinionsoftheCentralCommitteeoftheCommunistPartyofChinaontheImplementationoftheRuralRevitalizationStrategyissued in February 2018 stated the implementation of rural revitalization strategy is an inevitable requirement for solving the contradiction between unbalanced and inadequate development and the people’s ever-growing needs for a better life, an inevitable requirement for achieving the two centenary goals, and also for realizing common prosperity. Rational land use is the foundation of rural sustainable development and has important practical significance for promoting rural revitalization strategy. Therefore, it is necessary to conduct empirical research on small scale land use structure and layout optimization at village level.