2010, 32(1):184-194 第 32 卷 第 1 期 2010 年 1 月 Resources Science Vol.32, No.1 Jan., 2010 文章编号: 1007-7588(2010)01-0184-11 Pareto Optimal Land-use Patterns with Three Conflicting Benefits in an Area to the South of Liupan Mountain Qin Xiangdong1,2,Min Qingwen1,Li Wenhua1,Geng Yanhui1 (1.Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China; 2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China) Abstract: Optimal spatial patterns of land use and the associated optimal benefits are one of the key topics in land resources utilization, landscape ecology and sustainability science. However, research on this topic hasn’t made significant progress for many years in its optimization methodology, especially in multi-objective land-use optimization intending to systematically obtain all Pareto optimal solutions. This paper carried out an exploratory research on this frontier topic by optimizing a land-use pattern located in the south to Liupan Mountain in Jinghe watershed, China, with a total area of 300 km2, dominated by woodland, grassland and cultivated land. The research tried to maximize three objective functions of conflicting benefits (the average land productive potential of six crops, the total quantity of soil conservation, and sustainable habitat area for small woodland birds), by spatially reallocating woodland, grassland and cultivated land. Based on the grid data, the paper presented a strict mathematical formulation of land-use patch and pattern, simplified constraint of land suitability, land-use pattern optimization, and general conception of multi-objective optimization of land-use pattern. Spatial pattern of land-use was defined as an unknown function, with location and land-use type as its independent variable and dependent variable, respectively. Consequently, objective benefit subjected to optimization was defined as a function of this unknown pattern function, i.e. benefit functional. According to this mathematical representation, calculation approaches and calculation results of three sub-objectives for land-use were presented, including sustainable habitat area for small woodland birds on the basis of habitat network and ESLI (Ecologically Scaled Landscape Indices). Solution space of this three-objective optimization is a Pareto optimal front surface, which was demonstrated intuitively through its perspective drawing in 3-dimensional space, including some associated Pareto optimal land-use patterns. These optimization results (solution space) of the study area were analyzed through a general mode of “seven-section analysis”proposed, to get information about distribution and structure of the solution space relative to function values of original pattern, including the equilibrium optimal section and an equilibrium optimal pattern (with objective values all greater than those of original pattern) on it. The analysis conclusion of the equilibrium optimal section and pattern revealed to agree with qualitative analysis obtained from the original pattern map, land suitability map, and other parameter maps for calculation. This indicated that the model and the algorithm for the multi-objective optimization of land-use pattern are relatively reasonable. Key words: Optimization of land-use pattern; Multi-objective optimization; Land-use benefit; Pareto optimal front; Solution space; Liupan Mountain in Jinghe watershed, China 1 Introduction Although spatial patterns are attaching increasing importance to sustainable utilization of land resource and management of land-use[1], to systematically obtain all optimal spatial patterns of land-use is still a difficult problem[2], especially when optimality of the solutions involves several conflicting objective functions[3,4]. Traditional mode of “quantity optimization plus spatial allocation” for land-use planning can only provide several alternative land-use patterns, so that it can not meet sustainable utilization of land resource [5]. Very few researches on optimization for land-use patterns with two or more objectives involved “systematical” multi-objective optimization, except Received:January 5,2009; Accepted: March 15, 2009 Foundation item: National Basic Research Program of China (973 Program) (No. 973-2002CB111506). Author: Qin Xiangdong, male, postdoctoral of University of Science and Technology of China. His research focuses the fields of ecological planning of landscape. E-mail: [email protected] Corresponding author: Min Qingwen, His research focuses the fields of ecological agriculture and agricultural heritage conservation. E-mail: [email protected] http://www.resci.cn 185 秦向东等: 六盘山南麓具有三个冲突效益的 Pareto 最优土地利用格局 2 Mathematical Formulation Land-use Pattern Optimization for 2.1 Pattern and Patch of Land-use based on Raster Map A M × N sized raster map G consists of grids with a group of integer coordinates (i, j)=z: G ={(i, j) | i = 1,2,…,N; j= 1,2,…,M} (1) Land-use pattern P is taken as a function on G. P(z)=λ means land-use type of grid z∈G: P:G→L={cl(cultivated land), wd(woodland), gr (grassland), cn(construction land)} (2) Let Ω(G) be power set of the set G. H∈Ω(G) is a subset of G. For representation of land-use patch, definition of maximal connectivity about the subset H is given as follows: Definition 1. H is "maximal λ-connected" on the pattern P if and only if satisfying all three conditions as follows: (1) (i, j)∈H: P((i, j))= λ; (2) (i, j)∈H: (i-1, j)∈H or (i+1, j)∈H or (i, j-1)∈ H or (i, j+1)∈H; (3) (i, j) H and P((i, j))= λ: (i±1,j) H and (i, j± 1) H (3) Then all patches in a pattern P with land-use type of λ compose a set P, a functional determined by pattern function P and parametric variable λ: P(P, λ)={H∈Ω(G) | H is maximal λ-connected on P.} (4) A 2.2 Constraint Condition of Land Suitability Land suitability of a grid z with area a for land-use type λ may be expressed as a function: (5) Constraint condition of land suitability for pattern P is simplified as follows: z∈G: e(z, P(z))>0 or P(z)=P0(z) (6) where P0 is original land-use pattern. This constraint means that land-use type at grid z is transformed to another type that does not violate land suitability, or remains unchanged as that of the original pattern. A two approaches as following [6]: (1) to analyzing several typical scenarios with more than one conflicting objective benefit, and to providing only several near-optimal solutions [7, 8]; (2) to integrating multiple sub-objectives into one using mathematical approaches such as weighted sum, goal programming [9], etc. No research has been retrieved that optimized three or more objective benefits intending to systematically obtain a whole Pareto optimal front for land-use pattern. Most research on spatial optimization of land-use pattern aimed at solving practical problems in real geographic areas. On the other hand, very few researches on abstract pattern only optimized artificial, hypothetical small-sized pattern [10, 11]. It was difficult to confirm typicality of the former for optimization methodology of land-use pattern, while also difficult to confirm effectiveness of the latter for optimization of actual land-use pattern. This paper carried out an exploratory research on this frontier topic based on mathematical formulation of land-use pattern optimization problem, by optimizing a typical, actual land-use pattern of 300 km2 area located at the south to Liupan Mountain in Jinghe watershed, China. The research tried to maximize three objectives of conflicting benefits (the average land productive potential of six crops, the total quantity of soil conservation, and sustainable habitat area for small woodland birds), by spatially reallocating woodland, grassland and cultivated land. The whole solution space of this three-objective optimization, i.e., a Pareto optimal front surface, was demonstrated intuitively through its perspective drawing in 3-dimensional space, including some associated Pareto optimal land-use patterns. These optimization results (solution space) of the study area were analyzed through a general mode of “seven-section analysis”proposed, to get information about distribution and structure of the solution space relative to function values of the original pattern. It is indicated that the model and the algorithm for the multi-objective optimization of land-use pattern is relatively reasonable. The paper tried to demonstrate that key research on multi-objective optimization of land-use pattern should be to systematically explore maximal benefits space of multi-functional land-use patterns, not to provide a few optimal solutions for practical land-use planning. A A 2010 年 1 月 2.3 Objective Benefit Functional Objective function J of land-use benefit is taken as a function of an unknown function P, i.e. a land-use http://www.resci.cn 186 资 源 科 学 第 32 卷 第 1 期 pattern, so that J is a benefit functional: J: {P | z∈G: e(z, P(z)) >0 or P(z) =P0(z)} → R + (positive real number set) (7) Now problem of land-use pattern optimization may be formulated as follows: to seek an unknown land-use pattern function P so as to maximize the objective benefit functional J(P). So the main works for multi-objective optimization of land-use pattern is to find as many Pareto optimal patterns as possible, and to give their objective values in the form of Pareto optimal front. 2.4 General Conception for Multi-objective Optimization of Land-use Pattern In our study case, land productive potential, quantity of soil conservation, and sustainable habitat area were selected as three conflicting objective benefits subject to optimization, calculation approach of which are presented as follows. According to the above formulation, in the following algebraic expressions, parameters or variables with spatial variability are expressed as known functions with grid z as their independent variable or parametric variable. However, if the spatial variability is relevant to those of land-use type, these parameters or variables should be expressed as functional of unknown pattern A The above mathematical formulation may be extended directly to K-objective optimization of land-use pattern only if formula (7) is replaced by following one: Jk: {P | z∈G: e (z, P(z))>0 or P(z)=P0(z)}→R + , k = 1, 2, …, K (8) Nevertheless, for this multi-objective optimization, every sub-objective benefit functional Jk may conflict each other so that no global optimum but Pareto optimum [12] could be reached. Here we give some definition for solution of multi-objective optimization of land-use pattern, using Pareto optimality based on general conceptions of multi-objective optimization problem [13]. Definition 2. Land-use pattern“P is superior to P' ”if and only if both satisfy: k=1, 2, …, K: Jk(P)≥Jk(P') k=1, 2, …, K: Jk(P) > Jk(P') (9) And P is“Pareto optimal pattern”if and only if no other pattern is superior to P. Definition 3. Objective values of all Pareto optimal patterns compose “Pareto optimal solution set”, graphical representation of which is called“Pareto optimal front surface”, or“Pareto optimal front”for short. Definition 4. Pareto optimal pattern P is called an “equilibrium optimal pattern relative to the original pattern P0” , or “equilibrium optimal pattern” for short, if and only if: k=1, 2, …, K: Jk(P)>Jk(P0) (10) Definition 5. Objective values of all equilibrium optimal pattern compose “equilibrium optimal solution set”, graphical representation of which (a part of Pareto optimal front) is called“equilibrium section of Pareto optimal front”, or “equilibrium optimal section”for short. Pareto optimal solution set consists of reasonable solutions for a multi-objective optimization problem. A A A http://www.resci.cn 3 Calculations of Three Objective Functions for Land-use Benefits function P. 3.1 Land Productive Potential Using agro-ecological area method (AEZ), light-temperature potential productivity is calculated as follows. Parameters or variables include: average short-wave solar radiation above upper boundary of atmosphere, Ra (mm/d); average percentage of sunshine, n/N; maximal effective shortwave-radiation on clear day, Rse (cal/(cm2·d)); total productivity of dry matter on full cloudy day and cloudless day, b0 and bc (kg/(hm2·d)); daily mean temperature in whole growth period, T; leaf growth correction index, CL; harvest index, CH; length of growth period, Ng(d). Cloudiness fraction of a day: F(z)=(Rse-0.5 (0.25+0.5n/N(z))Ra·59)/0.8Rse (11) Proportional factor of maintenance respiration: Ct(z)= C30 (0.044+ 0.0019T(z) + 0.001T2(z)) (12) Light-temperature potential productivity (kg/hm2): Ym(z) =0.36 ·[F(z)·b0 + (1-F(z)) ·bc] ·CL·CH· Ng/(1+0.25Ng·Ct(z)) (13) The soil productive potentiality is calculated as follows, including Penman-Montieth recommended by FAO. Parameters or variables include: water demand coefficient kcj (the j-th phase); reference crop water demand ET0j; net radiation, Rn(MJ/(m2·d)); soil heat flux, G(MJ/(m2·d)); saturation vapour and actual water vapor pressure, es and ea (kPa); curve slope of 2010 年 1 月 187 秦向东等: 六盘山南麓具有三个冲突效益的 Pareto 最优土地利用格局 saturation vapor pressure - temperature, Δ (kPa/° C); psychrometer constant, γ (kPa/° C); crop coefficient, Kc; runoff coefficient, r; actual-rainfall, R(mm); soil moisture storage rate in fallow period, α; supplemental irrigation amount growth period, I (mm); yield coefficient, ky; and soil effective coefficient, g. Reference crop evapotranspiration (mm/d): (14) Total evapotranspiration of a crop: capacity larger than KP (Key Population) requires, i. e., its area is more than a threshold AKP = KP ·IAR. Additionally, total area of the habitat network is more than MVMPKP (Minimum Viable Meta-population with KP) requires, i.e. a threshold AMVMP+KP = MVMPKP· IAR. Category III: total area of the habitat network is more than MVMP (Minimum Viable Meta-population without KP) requires, i.e. a threshold AMVMP = MVMP·IAR. Then the second objective function J2, sustainable habitat area of a land-use P, is the total area of SHNs: (19) (15) Effective precipitation in fallow period and growth period, R'1 and R'2(mm): R'(z)=(1- r(z))·R(z) (16) Soil productive potentiality (kg/hm2): (17) The first objective function J1, total land productive potential of cultivated land of a land-use pattern P, is calculated as average value of that of several crops: (18) 3.2 Sustainable Habitat Area According to the conception of“key patch”[14] based on meta-population theory, Opdam et al (2003) [15] proposed “Ecologically Scaled Landscape Indices (ESLI)”as an evaluation index for sustainability of habitat. We calculated sustainable habitat area for small woodland birds using ESLI as follows. Any woodland patch H∈P(P,wd) large enough for double IAR (individual area requirement) of a bird was identified as a habitat patch. These habitat patches were taken as those in identical habitat network if and only if their distance is less than MDD (most dispersal distance) [14, 16]. Any habitat network is regarded as a SHN (sustainable habitat network) if and only if it meets at least one criterion listed below each for a certain category of sustainability. Category I: at least one patch has carrying capacity larger than MVP (Minimum Viable Population) requires, i.e., its area is more than a threshold AMVP = MVP·IAR. Category II: at least one patch has carrying 3.3 Quantity of Soil Conservation Using USLE (Universal Soil Loss Equation) [17], quantity of soil conservation Ec (t/hm2/a), i.e. the difference of potential and reality soil erosion (Ep and Er), is calculated as follows. Ec(z) = Ep(z) - Er(z) = R(z)·K(z)·LS(z)·[1- C(P(z))] (20) Parameters or variables include: rainfall erosive index, R; soil erodibility factor, K; slope length and gradient factor, LS; land surface vegetation cover factor, C, which is a known function determined by unknown pattern function P. The third objective function J3, quantity of soil conservation of a land-use pattern P, is the total value of Ec(z): (21) 4 Study Area and Its Original Land-use Benefits We focus on the problem of optimum land-use patterns in a farming-forestry-pastoral area in Jinghe (a second grade tributary of the Yellow River) watershed, China. The study area is located at the southeast to Liupan Mountain in the watershed, with length of 20km and width of 15km (Fig.1). Its original pattern of land-use is represented by a raster map with 400 × 300 grids, grid side-length of 50m (Fig.2, left), identical specification for land suitability map of study area (Fig.2, right). Land productive potential of six crops of study area is shown in Fig.3, left. According to section 3.1, the average land productive potential is (Fig.3, right) http://www.resci.cn 188 资 源 科 学 第 32 卷 第 1 期 J1 (P0) = 51.25×106kg. SHNs in the original pattern identified according to Section 3.2 are shown in Fig.4. Total area of SHNs of the original pattern is J2 (P0) = 5473ha. Soil erosion intensity of the study area is shown in Fig.5. According to Section 3.3, total quantity of soil conservation of the original pattern is J3 (P0) = 1.08× 106 t/a. 5 Results: Solution Space Three-objective Optimization Source: national resources and environment database in China (2000) Fig.1 Location of the study area By means of genetic algorithm[18, 19], for land-use pattern optimization problem of the study area, one thousand Pareto optimal solutions were found and represented by points, though which a smooth surface constructed by spline interpolation represents a Source: national resources and environment database in China (2000) Fig.2 Original land-use pattern (left) and land suitability (right) of study area Source: Chen Caocao [20] Fig.3 Land productive potential of six crops in study area (left) and their average value (right) http://www.resci.cn of 2010 年 1 月 189 秦向东等: 六盘山南麓具有三个冲突效益的 Pareto 最优土地利用格局 Fig.4 SHNs of original pattern in study area Size of blocks equals to area index. Radius of circle equals to MDD Pareto optimal front shown by perspective drawing in Fig.6. The Pareto optimal front surface is divided into seven sections by three plane that cross point 0# (representing land-use benefits value of the original pattern) and parallel to three coordinate plane. Pareto optimal patterns related to each point, and its three land-use benefit values, are shown in Fig.7. This Source: Geng Yanhui [21] Fig.5 Soil erosion intensity of the study area “seven section analysis” mode for three-objective optimization can give specific geometrical elements on the optimal front surface clear meaning as follows. (Word“increased”,“decreased” ,“unchanged”and “increment” in following text is comparative to benefits value of the original pattern.) Point 1#: unique optimal solution for single-objec- Fig.6 Perspective drawing of Pareto optimal front surface according to“seven section analysis”: solution space of three-objective optimization of land-use pattern of the study area Every point on the surface represents three objective function values of a Pareto optimal land-use pattern shown in Fig.7, with identical label (#). Coordinates of points are expressed as percentage relative to objective function value of original land-use pattern. So coordinates of point representing original pattern are (100, 100, 100) (0#). Gray point 20#, 21#, 22# are respectively on invisible section IV, V, VI of the surface, which has only one objective function value greater than those of original pattern. Visible section VII represents objective function values of optimal patterns that are all greater than those of original pattern. http://www.resci.cn 190 http://www.resci.cn 资 源 科 学 第 32 卷 第 1 期 2010 年 1 月 秦向东等: 六盘山南麓具有三个冲突效益的 Pareto 最优土地利用格局 191 Fig.7 Pareto optimal land-use patterns of the study area Three sub-objective function values in parentheses (land productive potential, sustainable habitat area, and quantity of soil conservation) are in turn expressed as percentage relative to those of original pattern, position of which on Pareto optimal front surface are shown in Fig. 6, with identical label (#). tive optimization of J3 (quantity of soil conservation); Point 2#: maximal solution for J3 if J1 (land productive potential) remains optimal solution of its single-objective optimization, similar meaning for point 3#, 4#, 5#; Plane curve 2-6-3, 4-5: all optimal solutions for sin- gle-objective optimization of J1 and J2 (sustainable habitat area), respectively; Plane curve 6-12-14-9: all Pareto optimal solutions for two-objective optimization of J1 and J3 with constraint of unchanged J2, similar meaning for plane curve 7-13-14-10 and 8-13-12-11; Space curve 3-7-4: all Pareto optimal sohttp://www.resci.cn 192 资 源 科 学 lutions for two-objective optimization of J1 and J2 without constraint of J3, similar meaning for space curve 1-10-11-2 and 5-8-9-1; Visible section I: all Pareto optimal solutions for three-objective optimization with J2 and J1 both increased at the expense of decreased J3, similar meaning for visible section II and III; Invisible section IV: all Pareto optimal solutions for three-objective optimization with only J1 increased at the expense of both J2 and J3 decreased, similar meaning for invisible section V and VI; Central visible section VII: equilibrium optimal solutions set for three-objective optimization with J1, J2 and J3 all increased. Point 25# is the position at which section VII is at a minimum distance from point 0#. 6 Discussion: Equilibrium Optimal Section and Pattern Compared with the whole Pareto optimal front, equilibrium optimal section VII is quite small in Fig.6, so that equilibrium optimal solutions are much fewer than other Pareto optimal solutions, which indicate comparatively few equilibrium optimal patterns, thus low optimization degree of freedom for all three land-use benefits increased. Distance between point 0# to 25# is only 8.1(% ), which indicates comparatively little increment of benefits value of equilibrium optimal patterns, thus small optimization range for all three benefits increased. Point 25# is much farther from 12# and 13# than from 14#, and far from the geometric center of section VII (point 26#), which indicates relatively few patterns with relatively large increment of J3 among all equilibrium optimal patterns. An equilibrium optimal pattern, 26#, is analyzed as shown in Fig.8. Referred to original land-use pattern Fig.8 An equilibrium optimal land-use pattern of study area (The pattern 26# in Fig.6 and Fig.7) http://www.resci.cn 第 32 卷 第 1 期 (Fig.2, left), land suitability map (Fig.2, right), land productive potential and soil erosion map of original land-use pattern (Fig.3 and Fig.5), characteristics of the pattern 26# are listed below. 1) Land suitable for pasture (or for both pasture and forestry) with high potential erosion modulus were allocated whole large pieces of grassland; 2) Land suitable for farming (or for both farming and pasture) with high land potential productive were allocated whole large pieces of cultivated land; 3) Woodland were relatively connected and concentrated. Narrow woodland patches connecting whole large woodland and small pieces of woodland let all sustainable habitats become SHN of category I. 4) Though land-use type was transformed in many locations, area of woodland and grassland increased only a little, and area of cultivated land decreased only a little. These characteristics justified this equilibrium optimal pattern as follows. The pattern made full use of spatial variability of soil productive potentiality and potential erosion, so as to increase J1 in spite of slightly decreased cultivated land, and to increase J2 and J3 in spite of almost unchanged area of woodland and grassland. The pattern also increased J2 by connecting and concentrating small woodland patches to large one. J1, J2 and J3 of the pattern increased by 6%, 5% and 4%, respectively. 7 Conclusion Representative study cases of systematical optimization of spatial pattern for land-use are rare to find, especially multi-objective optimization for land-use of real geographic area (except those which integrate multiple objectives into one). This paper carried out an exploratory research on this topic by a three-objective optimization of an actual land-use pattern at large scale. The research is in favor of such a hypothesis that key research on multi-objective optimization of land-use pattern should be to systematically explore maximal benefits space of multi-functional land-use pattern, not to provide one or several optimal solutions for practical land-use planning. For this purpose, strict mathematical formulation for land-use pattern optimization, intuitive and informative expression of solution space, and meaningful analysis mode of the solution space were introduced through 2010 年 1 月 秦向东等: 六盘山南麓具有三个冲突效益的 Pareto 最优土地利用格局 pattern function and its object benefit functional, Pareto optimal front surface, and an analysis mode of “seven-section analysis” , respectively. The analysis conclusion of equilibrium optimal section and pattern was revealed to agree with qualitative analysis obtained from original pattern map, land suitability map, and other parameter map for calculation. This indicated that the model and the algorithm for the multi-objective optimization of land-use pattern are primarily reasonable. 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(in Chinese) http://www.resci.cn 194 资 源 科 学 第 32 卷 第 1 期 六盘山南麓具有三个冲突效益的 Pareto 最优土地利用格局 秦向东 1,2,闵庆文 1,李文华 1,耿艳辉 1 (1. 中国科学院地理科学与资源研究所,北京 100101;2. 中国科学院研究生院, 北京 100049) 摘 要: 土地利用空间最优格局及其相应的最优效益是土地资源利用、景观生态学和可持续发展科学的关键 课题之一,多年来在其优化方法论上未能取得明显进展,尤其在多目标土地利用空间格局优化中系统地获 取所有 Pareto 最优解及其解空间的分析方面。已有的土地利用空间格局优化研究大多数停留在“先数量优 化、后空间配置”的两步走模式,以及利用目标规划等数学方法将多个优化目标转化为单个目标的简化模 式。本文通过优化一个农林牧交错地域的土地利用格局,在方法论上对这一前沿课题作了探索性研究。研 究通过林地、草地、耕地的空间调整,最大化平均土地生产潜力、土壤保持总量、小型林地鸟类可持续生境面 积这 3 个相互冲突的效益目标函数。首先基于栅格数据,给出了土地利用斑块与格局、土地利用格局优化、 简化的土地适宜性约束的严格的数学表述,以及多目标土地利用格局优化的一般概念或定义,包括某种土 地利用类型的最大连通性、土地适宜性函数、两个格局的优于关系、Pareto 最优集及前端曲面、均衡最优解和 均衡最优格局。栅格图上的土地利用空间格局被定义为以空间位置为自变量、以土地利用类型为因变量的 未知函数。相应地,待优化的效益子目标被定义为这个未知格局函数的函数,即效益泛函。然后,按照这种 数学表述给出了土地利用效益的 3 个子目标的计算方法:基于 AEZ 方法(agro-ecological area method,农业生 态区划法)的平均土地生产潜力总量、基于生境网络斑块和 ESLI(Ecologically Scaled Landscape Indices,生态 标度的景观指数)的小型鸟类的可持续生境面积、基于 USLE (Universal Soil Loss Equation,通用土壤侵蚀方 程)的土壤保持总量。选取中国泾河流域六盘山南麓一个 300km2 的土地利用格局作为研究区域,给出了在 研究区土地利用现状格局之下这 3 个土地利用效益子目标函数的计算结果,包括基于 ESLI 的三类可持续生 境网络斑块的分布与面积。最后,在三维空间中用透视图直观展现了研究区三目标优化问题的解空间—— Pareto 最优前端曲面,以及相应的 Pareto 最优土地利用格局。提出通用的“七区分析”模式,来分析这些优化 结果(解空间),以获得解空间相对于现状格局目标函数值的分布情形,包括各个特定点、交线及边界线、各 个分区所表现的空间结构、总体趋势、边界特征、均衡最优解及有关的均衡最优格局。其中均衡最优格局与 根据现状格局图、土地适宜性图以及其他计算参数图所作的定性分析结果一致,初步表明此多目标土地利 用格局优化的模型与算法基本合理,即:能够充分利用与土地利用相关的自然属性的空间变异性,在不显著 改变各类土地利用面积的情况下增进三类土地利用目标效益。本文的研究方法强调严格的数学表述、完备 的解空间获取、信息丰富而直观的解空间的表达方式与分析模式,其研究结果虽然还难以直接应用在实际 的土地利用规划中,但是它有利于这样一种假设:多目标土地利用格局优化的核心研究内容,不是为具体的 土地利用规划提供有限个方案,而是要探索、了解在自然状态下,多种土地利用效益的极大化空间。 关键词:土地利用格局优化;多目标优化; 土地利用效益;Pareto 最优前端;解空间; 泾河流域六盘山 http://www.resci.cn
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