Spatial-temporal pattern and formation mechanism of county urbanization on the Chinese Loess Plateau

Urbanization is a comprehensive and complex socioeconomic phenomenon that plays an influential role in promoting global socioeconomic development. The Loess Plateau region is an important part of the China's ecological security pattern, and occupies an important position in the implementation of China's new-type urbanization strategy and the realization of the urban dream. The characteristics of the staged changes and regional differentiation of urbanization in the area from 1990 to 2018 were studied with focus on regions and subregions by selecting 341 county-level administrative units on the Chinese Loess Plateau as the research area, and employing partition analysis and geographic detector methods. This revealed the formation mechanism of the spatial differentiation pattern of urbanization on the Loess Plateau. We found that the urbanization of the Loess Plateau,previously in a slow growth phase, entered the accelerated development phase, presenting a macro pattern of high rates of urbanization in central and eastern areas and low rates in western areas. The formation of the regional differentiation patterns of urbanization on the Loess Plateau were the combined results of natural geographical and socioeconomic factors. Among these factors, the interaction of any two factors had a stronger impact on regional urbanization patterns than a single factor, which was specifically manifested as nonlinear or bi-factor enhancement effects. The findings of this paper may provide a theoretical reference and scientific basis for the scientific promotion of healthy urbanization on the Chinese Loess Plateau and the ecologically fragile areas of developing countries around the world.     

Spatio-temporal evolution of ecologically-sustainable land use in China's Loess Plateau and detection of its influencing factors

Ecological land(Eco-land) is a basic resource for human beings to survive, and eco-land use is a strategy, a way to manage the land resource. So, ecologically-sustainable land use is essential for human beings to survive. This paper investigates the spatiotemporal characteristics and mechanisms of urban-rural eco-land using a new and innovative integration way based on eco-land change data in China's Loess Plateau(LP) prefecture level cities and explores factors of eco-land change. The spatial difference characteristic of eco-land among different level cities in the LP is that: small cities big cities middle cities. From 2009 to 2016, the eco-land in the LP from the perspective of urban-rural areas has changed significantly. Significant differences of urban-rural eco-land were identified among various urban growth types, and all the cities in the LP were further classified into four types based on eco-land change trend, with type A and B cities identified as the vital zone and major zone. Taking the eco-fragile region Loess Plateau(LP) as an example, our results demonstrated that the migrants to cities in LP could relieve ecological pressures and promote restoration of ecological vegetation. We have demonstrated that urbanization and the influence of government policy can be discerned through the quantification of the spatial-temporal change of eco-land and suggest that combining both urban and rural eco-land can support more effective land use decisions and provide theoretical basis for the practical application of urban planning, policy-making and sustainable development. What's more, governments should strive to population mobility and restore vegetation to sustain this fragile ecological environment.     

Optimization of Rural Settlement Distributions Based On the Ecological Security Pattern: A Case Study of Da'an City in Jilin Province of China

Following the trends of Chinese rural transformation development, and the sustainable development goals for resources and environment, reasonable arranging the potential development space and the ecological space, so as to optimize the distributions of rural settlement would be the key challenge for rural areas in ecologically fragile regions. From the perspective of maintaining regional ecological security, this paper takes Da'an City, a typical ecological fragile region in Jilin Province, as the case area, constructing the comprehensive ecological security pattern(ESP) on basis of landscape ecology, and applying the landscape pattern indexes to quantitative analysis the spatial distribution characteristics of rural settlements. Then, different optimization directions and management strategies are put forward for rural settlements in each secure zone under the comprehensive ESP. The experimental results showed that 1) the area of the low security zone, the general security zone, the moderate security zone and the extreme security zone was 1570.18 km~2, 1463.36 km~2, 1215.80 km~2 and 629.77 km~2, representing 32.18%, 29.99%, 24.92% and 12.91% of the total area of the target area, respectively. 2) The rural settlements in Da'an City were characterized by a high degree of fragmentation with a large number of small-scale patches. 3) The area of rural settlements in the ecological relocation zone, the in situ remediation zone, the limited development zone and the key development zone was 22.80 km~2, 42.31 km~2, 36.28 km~2 and 19.40 km~2, accounting for 18.88%, 35.03%, 30.04% and 16.06% of the total area of rural settlements, respectively. Then, different measures were proposed for settlements in different optimization zones in order to scientifically plan important ecological space, production space and living space in rural areas. This paper aims to provide fundamental support for rural settlements based on redistribution from the perspective of landscape ecology and provide insights for rural planning and rural habitat environmental improvement.     

Mountain Land Use Planning of Metropolitan Suburbs： the Case of the Jinyun Mountain and Its Surrounding area, Chongqing, China

Open space of metropolitan suburbs in mountain region, has been increasingly becoming the coupling mosaic structure of industrial actions and landscape behaviors. However, the local governments, when making land use planning, often aim at economic development, and rarely refer to the coordination of compatibilities and conflicts between industrial actions and landscape behaviors in the mosaic structure. In this study land use in the Jinyun Mountain and its surrounding area, Chongqing is adjusted by gray multi-objective programming approach and local-level decision-making process to cope with conflicts between objectives for human welfare and objectives for landscape conservation. The results indicate that： 1） the compatibilities and conflicts among different behavior characters and different landscape types result in the compatibilities of landscape to human behavior; 2） a land use planning in the study area is produced based on the sustainable land use and social-eco development, which pays more attention to the resources and environment constraints and economic objectives, and follows the distribution law of rare resources; 3） in the study area, cultivated land of 1,207.27 ha can meet the demands for food and byproducts by the residents there, orchard land and forestland of 632.55 ha, 2,276.61 ha, respectively can provide enough spaee for the local people to improve their living structure and meet their demands for reereational activities, and urban residential land, rural residential land, mining land and transportation land of 1107.60 ha, 120.27 ha, 162.48 ha, 100.91 ha, respeetively can satisfy the resident＇s eeonomie development and infrastructures; 4） the equilibrium among industrial actions, landscape accessibility and ecological conservation can be obtained by analyzing the possible impaets of human activities on landscape eeologieal proeess in open spaee of metropolitan suburbs in mountain areas.     

基于DEM的黄土地貌逼近度因子构建及特征分析

沟谷源点作为沟沿线上最为活跃的部位,其分别到上游分水线、下游沟谷线的流线空间比对关系,是表征三线空间结构的重要突破口。它在空间上向流域分水线逼近的程度,是量化黄土流域地貌系统发育程度的重要切入点。为探究黄土地貌区流域沟谷源点向流域分水线逼近的程度,揭示黄土流域地貌发育进程及该进程所表现的主要侵蚀方式,本文从水平和垂直2个维度,构建量化三线空间结构关系的核心因子--逼近度(PI),其中包括水平逼近度(HPI)和垂直逼近度(VPI),基于5 m分辨率数字高程模型,在陕北黄土高原遴选了包含16种地貌类型的42个样区,利用数字地形分析方法,探讨其平均值(MHPI, MVPI)的空间分异规律。另外,选择其中南北序列分别代表黄土塬、残塬、梁状丘陵沟壑和峁状丘陵沟壑区的淳化、宜君、甘泉和绥德4个地区,完备包含一至五级别沟谷的典型流域为重点实验样区,探讨陕北黄土高原流域尺度平均逼近度变异指数(MPIV)序列性特征。实验结果表明:①陕北黄土高原平均逼近度(MPI)存在强烈的空间自相关,MHPI在南北序列上先增大后减小,东西方向上逐渐减小,在黄河沿岸峡谷丘陵区MHPI达到最大;MVPI由西南-东北先减小后增加,由西北-东南逐渐减小,在渭北黄土台塬区达到最小;②在流域尺度上,MPIV值的正负与黄土塬区、丘陵沟壑区敏感相关;③4个重点样区MHPI、MVPI与其它地形因子存在南北序列上的一致性。104个外部汇流区平均水平逼近度与平均坡度相关性较好(P=0.43, a<0.001),平均垂直逼近度与面积高程积分强烈相关(P=0.75, a<0.001)。平均逼近度指标综合考量了黄土高原地区最典型的三条具有结构控制意义特征线的空间关系,对黄土地貌的发育程度有明显的指示性意义。     

青藏高原城乡建设用地和生态用地转移时空格局

青藏高原作为中国重要的生态环境保护地,城镇化和生态环境的变化受到广泛关注。本文基于1990-2015年土地利用数据,进行生态用地和城乡建设用地之间的转移分析,通过核密度以及标准差椭圆分析进行空间转移强度的定性研究。结果表明：① 1990-2015年青藏高原生态用地显著地向城乡建设用地转移,是城乡建设用地向生态用地转移量的54.6倍,其中2000-2005年和2010-2015年是用地转移的热点时期;② 城乡建设用地与生态用地之间的转换在空间上呈现逆向状态,生态用地向城乡建设用地的转移分布逐渐从青藏高原的周边区域向腹地蔓延;城乡建设用地向生态用地的转移最初出现在青藏高原的腹地,逐渐向外围扩张;③ 生态服务功能越大的生态用地,越容易被人类占用,随之发生用地类型的转移,侵占后的土地很难反向转移为具有高生态服务功能的生态用地。     

Seasonal variations in the influence of vegetation cover on soil water on the loess hillslope

Soil water is the key factor that restricts the restoration of the local ecological systems in the Loess Plateau of China. Studying the effects of vegetation types on soil water and its seasonal variation helps to understand hydrological characteristics and provides insights into the sustainable restoration of vegetation. Therefore, the Caijiachuan watershed was chosen as the research object to investigate the water status of a 0-10 m soil layer under different vegetation types including Pinus tabulaeformis, Robinia pseudoacacia, Platycladus orientalis, apple orchard, natural forestland,farmland and grassland. By comparing the difference between soil water of different land use types and that of grassland during the same period, the seasonal changes of soil water status of different types were judged. The results show that(1) in the 0-10 m soil layer, the largest value of soil water content was in the0.3-0.4 m layer, and the lowest was in the 5.6-5.8 m layer. The depths at which the vegetation cover influenced the soil water were up to 10 m;(2) among summer, fall and spring, the soil water storage wasthe highest in the fall. In addition, the lowest value of relative accumulation was in the fall, which was the period in which the soil water recovered;(3) the soil water in the 0-10 m layer was in a relatively deficient state in the artificial forestlands, apple orchards and native forestlands, while the relative accumulation was in the farmland. In addition, the relative deep soil layers(8-10 m) had more serious deficits in the areas in which P. tabulaeformis, R. pseudoacacia and the apple orchard grew;(4) during the study period, the farmland in the summer had the largest relative accumulation(182.71 mm), and the land under R.pseudoacacia in the fall had the lowest relative deficit(512.20 mm). In the Loess Plateau, vegetation cover will affect the change of deep soil moisture and artificial forest will cause soil water loss in different degrees.     

Coupling mechanism of rural settlements and mountain disasters in the upper reaches of Min River

Human settlements are the place where human beings live,among which the rural settlements can be regarded as a reflection of human-land relationship in mountain areas because their vertical distribution is greatly influenced by the specific geographical environment and ecological conditions of mountains.Based on field investigation,this paper uses physical,geographical,and ecological theories to make a comprehensive study of rural settlements and mountain disasters in the upper Min River,which is an ecologically fragile area with high-frequency disasters（collapse,landslide,debris flow,etc.） and a minority inhabit district.By applying these modern scientific theories,this paper attempts to shed some light on the relationship between rural settlements and mountain disasters.Consequently,an in-depth understanding of this relationship was achieved as follows：（1） Rural settlements and mountain disasters are mainly distributed in the intercepted flows of water and soil; and both quantity and quality of arable lands in mountains are important indicators of these flows.（2） The Small Watershed Management Project is a complex system of rural settlements and mountain disasters that interacts with and constrains the ecological system.By this project,the human survival will be better guaranteed.Being fundamental for the ecological reconstruction,the coupling mechanism of rural settlements and mountain disasters is not only an engine to promote harmonious development between human and nature,but also a bridge to link them.     

Human settlement evaluation in mountain areas based on remote sensing, GIS and ecological niche modeling

The Qinghai-Tibet Plateau is the world’s highest and largest plateau. Due to increasing demands for environment exploration and tourism, a large transitional area is required for altitude adaptation. Hehuang valley, which locates in the transition zone between the Loess Plateau and the Qinghai-Tibet Plateau, has convenient transportation and relatively low elevation. Our question is whether the geographic conditions here are appropriate for adapted stay before going into the Qinghai-Tibet Plateau. Therefore, in this study, we examined the potential use of ecological niche modeling (ENM) for mapping current and potential distribution patterns of human settlements. We chose the Maximum Entropy Method (Maxent), an ENM which integrates climate, remote sensing and geographical data, to model distributions and assess land suitability for transition areas. After preprocessing and selection, the correlation between variables and spatial autocorrelation input data were removed and 106 occurrence points and 9 environmental layers were determined as the model inputs. The threshold-independent model performance was reasonable according to 10 times model running, with the area under the curve (AUC) values being 0.917 ± 0.01, and 0.923 ± 0.002 for test data. Cohen’s kappa coefficient of model performance was 0.848. Results showed that 82.22% of the study extent was not suitable for human settlement. Of the remaining areas, highly suitable areas accounted for 1.19%, moderately for 5.3% and marginally for 11.28%. These suitable areas totaled 418.79 km², and 86.25% of the sample data was identified in the different gradient of suitable area. The decisive environmental factors were slope and two climate variables: mean diurnal temperature range and temperature seasonality. Our model showed a good performance in mapping and assessing human settlements. This study provides the first predicted potential habitat distribution map for human settlement in Ledu County, which could also help in land use management.     

复杂网络理论在黄土高原沟谷地貌特征研究中的应用

沟谷侵蚀是塑造黄土地表侵蚀形态的主要动力,沟谷的发育过程深刻地影响着黄土地貌的发育及演化。本文在黄土高原选择6个典型地貌样区,以样区的数字高程模型为基本数据源提取沟谷系统。将沟谷系统中的沟谷节点、沟谷源点和流域出水口点作为网络节点,网络节点之间的空间拓扑关系为边,高程差为权值,构建黄土高原沟谷加权复杂网络模型。对黄土沟谷地貌的节点特征和空间结构进行定量刻画和分析,得到黄土高原不同地貌类型网络特征的空间格局及其变化,并进一步映射地貌的发育过程及演化机理。研究结果表明：① 黄土高原沟谷加权网络的点强度累积概率分布呈指数分布,相关性系数皆达到0.80以上,该网络正处于向无标度网络转化的过渡期;② 样区从南到北,沟谷特征点的点强度值呈现逐渐减小的态势,且点强度的分布具有不对称性,沟谷右侧侵蚀强度较高,点强度分布较多;③ 平均路径长度和网络结构熵值在绥德一带最大,分别为30.94、6.31,并向南北两侧呈减少的趋势,网络密度值的变化与之相反;3个指标分别从网络结构的连通性、稳定性和紧密性反映了不同沟谷地貌类型的侵蚀程度以及地貌系统的演化机理;④ 网络指标与传统地貌指标的相关性系数均超过0.85,其可以科学、准确地表达地貌形态的复杂性及地貌的发育阶段,有望作为沟谷地貌地学特征研究的参数。该方法考虑了沟谷地貌的空间拓扑关系以及系统的整体性,为复杂表面形态的地貌研究提出了一种新的思路和方法。     

三北工程区植被恢复对土壤风蚀的影响及植被恢复潜力研究

三北地区是我国重要的生态屏障,分析2000—2019年三北防护林体系建设工程（简称：三北工程）区植被恢复时空变化状况,厘定人类活动与气候要素对植被恢复的贡献,探究植被恢复对土壤风蚀影响,评估植被恢复潜力空间,可为三北防护林体系建设工程未来规划管理和科学施策提供参考。本文在选取植被覆盖度和植被净初级生产力表征植被恢复状况基础上,利用地面数据,结合模型模拟,定量评估了2000—2019年三北防护林体系建设工程区植被恢复程度及其对土壤风蚀的影响,并对植被恢复潜力进行探究。研究结果表明：① 2000—2019年植被恢复程度高、较高的面积,占总面积的35.29%和13.16%,主要分布在黄土高原区及北部区域和风沙区与东北华北平原农区的部分地区。人类活动与气候因素对植被恢复贡献率为10.45%和89.55%;② 土壤风蚀以轻度侵蚀和微度侵蚀为主,呈逐年下降趋势,剧烈侵蚀面积减少了66.45%,防风固沙服务得到进一步提升。植被恢复程度与土壤风蚀模数呈负相关关系,植被恢复程度较好有助于降低土壤风蚀模数;③ 三北工程区森林、草地和荒漠生态系统仍有8.16%的恢复潜力,内蒙古高原北部部分地区、哈顺戈壁北部和准噶尔盆地西北部及周边区域、黄土高原南部部分区域存在较大恢复潜力。     

Comprehensive development of agriculture in the Loess Plateau Area

The Loess Plateau is one of China s developing areas where socio-econ-omy is backward, ecological environment deteriorated and people's life difficult.The purpose of carrying out comprehensive development of the area's agriculture is, in essence, to open up new fields of agro-production, to intensify the utilization of related resources, to raise productivity and to win bigger output. The decision is important, as by so doing, the physical landscape could be tranformed, the local economy could be flourished, and the people's standard of living could be improved, and moreover the national development strategy of "depending on the East and shifting to the West" and building Shanxi Province into an energy and chemical industrial base could be realized.Based on field investigations in recent years, the auther proposed the purpose, target, principles, steps, tactics and strategies for the comprehensive development of the are's agriculture.     

Revisiting Sustainable Development of Dry Valleys in Hengduan Mountains Region

Dry valleys are a striking geographic landscape in Hengduan Mountains Region and are characterized by low rainfall, desert type of vegetation and fragile environment. Past efforts and resources have been concentrated mainly on rehabilitation of degraded ecosystem and fragile environment, particularly reforestation, while socio-economic development has been largely overlooked. Despite successes in pocket areas, the overall trend of unsustainability and environmental deterioration are continuing. It is important to understand that uplift of the Tibetan Plateau is the root cause of development of dry valleys, and development and formation of dry valleys is a natural process. Human intervention has played a secondary role in development of dry valleys and degradation of dry valleys though human intervention in many cases has speeded up environmental degradation of the dry valleys. It is important to understand that dry valleys are climatic enclaves and an integrated approach that combines rehabilitation of degraded ecosystems and socio-economic development should be adopted if the overall goal of sustainable development of dry valleys is to be achieved. Promotion of niche-based cash crops, rural energy including hydropower, solar energy, biogas and fuelwood plantation is recommended as the priority activities.     

黄土高原地貌形态图谱三维符号指标体系与应用

长期以来,地貌学界和制图学界一般是采用文字、地图和图像等方式来描述黄土高原独特的地貌形态,故往往不够形象,缺乏系统性。采用地学信息图谱和三维可视化的方法,对挖掘揭示黄土高原地貌形态特征规律是一个有效的方法。黄土高原地貌形态图谱三维符号的指标体系,是将地貌学家和制图学家对黄土高原正负地貌类型的认知结果经过系统化、标准化和科学化的归纳和提炼,从中提取出的描述黄土高原地貌三维特征的参数集合。既是对黄土高原地貌形态图谱三维立体特征的充分概括,又是三维形式建模表达的参考和依据。根据黄土高原地貌类型的分类和侵蚀特征规律,该体系分为正地貌形态指标体系、负地貌形态指标体系和坡度一侵蚀特征谱系描述指标,采用定性和定量相结合的方法来制定指标体系的具体参数。最后通过实例来验证指标体系在构造三维符号时的应用。细致精确的描述单个地貌类型的三维形态,将有助于对黄土高原地貌特征的认识和研究,为水土保持和生态环境建设提供帮助,同时也为其他地貌类型的信息图谱研究提供借鉴。     

THE LANDSCAPE ECOLOGICAL ，ASSESSMENT AND PLANNING IN THE CONTOL WATERSHED BY RESERVOIR OF ERLKONG MOUNTAIN

Based on the theories of landscape ecology,landscape eco-environment in the coutrol watershed by reser-voir of Erlong Mountain in Heilogjiang Province was analyzed and assessed by using GIS technique and statistical model of Principal Component Analysis and Spatial Cluster Analysis.It is found that 100.08km^2(36%) of the total area is in the state of kilter,85.73km^2(31%) of the total area is in the state of general,and 47.26km^2(17%) and 15.48km^2(16%) is in the relatively poor state and ideal state.According to landscape ecological structure,there are three land-scape function areas being planned and designed.1) Agricultural landscape function area:its developmental direction is tour agriculture and high-benefit agriculture.2)Eco-environment protected function area:the direction of development and utilization of this region is to develop vigorously forest for soil and water conservation ,and try to increase the rate of vegetation cover.3)Forest landscape function area:rational cut and utilization of forest resources,space optimization disposal of category of forest ,foster of forest and protection of wildwood will become the main development directions for this region.This study trys to provide scientific foundation for ecological restoration of the whole valley and its sustain-able development.     

长沙市游憩-居住功能空间格局及其匹配关系研究

伴随新型城镇化和全面休闲化时代到来,游憩-居住两大功能空间关系研究成为新时期城市地域结构领域的重要关注议题。基于POI地理空间大数据,通过运用Ripley's K函数、同位区位商、“不一致指数”定量模型和采用全局空间自相关、核密度估计等ArcGIS空间分析方法,探究了长沙市游憩-居住功能空间格局及其匹配关系特征。研究发现：① 两大功能空间均具有显著的空间正相关性,形态格局差异鲜明且均呈以“空间极核”为导向的集聚模式,各类型功能空间集聚强度表现为“居住空间>文化休闲空间>体育健身空间>商业娱乐空间>自然生态空间”;② 两大功能空间存在基于“距离-数量”的函数衰减关系,距离居住空间3000 m半径环带是游憩空间集中分布以及居民日常游憩休闲的重要活动范围;③ 居住空间具有“临近”游憩空间布局的指向特征,但反之不显著,两大功能空间呈单向吸引“非对称性”错位临近关系,居住空间临近不同类型游憩空间的指向强度呈“体育健身空间>文化休闲空间>自然生态空间>商业娱乐空间”位序格局;④ 游憩-居住功能空间协调关系具有较强的空间异质性,湘江西岸整体上优于东岸,岳麓区、望城区为游憩-居住协调型,天心区、芙蓉区、雨花区、开福区为游憩滞后居住型,长沙县为游憩超前居住型。本研究通过聚焦新型城镇化和全民休闲时代的城市游憩设施配置及其与居住空间的关系问题,将为丰富传承新背景趋势下的城市公共设施区位理论、城市空间结构理论等提供重要的理论探索方向,并为长沙市及国内同类大都市合理布局城市游憩休闲设施、优化调整城市空间结构和建设休闲宜居城市等提供科学参考。     

Review of Digital Elevation Model （DEM） Based Research on China Loess Plateau

Introduction The Loess Plateau is located in the upper and middle reaches of the Yellow River, among the western Taihang Mt, eastern Riyue-Helan Mt, northern Qinling Mt, and southern Yinsan Mt (from 100°54′to 114°33′E and 33°43′to 41°31′N; Figure 1). It covers a total area of 624,000 km2. The Loess Plateau of China has drawnworldwide attention in geographical research for its unique morphological features, abundant nature resources, most serious soil erosion, as well as its pot…     

Age-related changes of carbon accumulation and allocation in plants and soil of black locust forest on Loess Plateau in Ansai County,Shaanxi Province of China

The effects of reforestation on carbon(C) sequestration in China′s Loess Plateau ecosystem have attracted much research attention in recent years. Black locust trees(Robinia pseudoacacia L.) are valued for their important use in reforestation and water and soil conservation efforts. This forest type is widespread across the Loess Plateau, and must be an essential component of any planning for C sequestration efforts in this fragile ecological region. The long-term effects of stand age on C accumulation and allocation after reforestation remains uncertain. We examined an age-sequence of black locust forest(5, 9, 20, 30, 38, and 56 yr since planting) on the Loess Plateau to evaluate C accumulation and allocation in plants(trees, shrubs, herbages, and leaf litter) and soil(0–100 cm). Allometric equations were developed for estimating the biomass of tree components(leaf, branch, stem without bark, bark and root) with a destructive sampling method. Our results demonstrated that black locust forest ecosystem accumulated C constantly, from 31.42 Mg C/ ha(1 Mg = 10~6 g) at 5 yr to 79.44 Mg C/ha at 38 yr. At the ′old forest′ stage(38 to 56 yr), the amount of C in plant biomass significantly decreased(from 45.32 to 34.52 Mg C/ha) due to the high mortality of trees. However, old forest was able to accumulate C continuously in soil(from 33.66 to 41.00 Mg C/ha). The C in shrub biomass increased with stand age, while the C stock in the herbage layer and leaf litter was age-independent. Reforestation resulted in C re-allocation in the forest soil. The topsoil(0–20 cm) C stock increased constantly with stand age. However, C storage in sub-top soil, in the 20–30, 30–50, 50–100, and 20–100 cm layers, was age-independent. These results suggest that succession, as a temporal factor, plays a key role in C accumulation and re-allocation in black locust forests and also in regional C dynamics in vegetation.     

Spatial Heterogeneity of Agricultural Science and Technology Parks Technology Diffusion: A Case Study of Yangling ASTP

Agricultural science and technology parks(ASTPs) represent an important growth pole in China's agricultural modernization.Clarifying their diffusion laws can optimize the technological diffusion process and improve its efficiency. Our study uses disaggregated spatial information in its model to analyze ASTP technology diffusion in a heterogeneous space. We constructed a comprehensive index system to evaluate the diffusion environmental quality and introduced the heterogeneous diffusion equation to calculate the technological diffusion probability. We applied this framework to a real-world scenario: the apple planting technology diffusion of the Yangling ASTP in the Loess Plateau, China. The results indicated: 1) the technological diffusion environment of the Loess Plateau advantageous apple producing area showed strong spatial heterogeneity caused by climate, topography, and external transportation links.2) Under the combined effects of distance and spatial heterogeneity, the spatial diffusion pattern of the Yangling ASTP apple technology was expansion diffusion supplemented by hierarchical diffusion and banded diffusion, and 3) ASTP technology diffusion showed a strong distance attenuation effect, and the frictional effect of distance can be decreased by improving the diffusion environmental quality. These laws can promote regional balanced ASTP-driven development.     

Analysis of comprehensive benefits of transforming slope farmland to terraces on the Loess Plateau: A case study of the Yangou Watershed in Northern Shaanxi Province, China

De-farming slope farmland has been an effective measure in recent years to improve environment and prevent soil and water loss on the Loess Plateau.There are different views about the defarming method,and also various de-farming patterns have been put into practice.This paper takes the Yangou Watershed in Shaanxi Province of China as a case for studying the comprehensive benefits of transforming slope farmland to terraces.Based on the day-by-day meteorological data of the Yan'an station in 2005 and the data...