Spatio-temporal variation and the driving forces of tea production in China over the last 30 years

As a daily necessity and an important cash crop in China and many other countries, tea has received increasing attention. Using production concentration index model and industry’ s barycenter theory, we analyzed the spatio-temporal distribution of tea production and barycenter movement trajectory of tea plantations and production in China between 1986 and 2015. Driving forces of the movement were also analyzed. From 1986 to 2000, tea production in China’s Mainland of grew slowly (by 210×10³ t). The continuous increase in tea yield per unit area was the primary contributor (more than 60%) to the growth in tea production during this period. Since China joined the World Trade Organization (WTO) in 2001, tea production has grown rapidly, by 1.59×10⁶ t between 2001 and 2015. The increase in the tea plantations area is the main contributor. Over the last 30 years, the barycenters of tea production in China have moved westward from the Dongting Lake Plain to the eastern fringe of the Yunnan-Guizhou Plateau. Guizhou, Guangxi, and Sichuan in southwestern China have gradually become regions of new concentrated tea plantations and main tea production provinces. Lower cost of land and labor in southwestern China are the main drivers of the westward movement of China’s tea industry. In addition, supportive policies and the favorable natural geographical environment contribute to the westward movement of tea industry. Our research highlights the spatio-temporal variation of China’s tea production in the last three decades. The result indicates importance to make appropriate policies to promote the development of tea industry in China.     

Modeling the spatio-temporal changes in land uses and its impacts on ecosystem services in Northeast China over 2000–2050

Land use and its dynamics have attracted considerable scientific attention for their significant ecological and socioeconomic implications. Many studies have investigated the past changes in land use, but efforts exploring the potential changes in land use and implications under future scenarios are still lacking. Here we simulate the future land use changes and their impacts on ecosystem services in Northeast China (NEC) over the period of 2000–2050 using the CLUE–S (Conversion of Land Use and its Effects at Small regional extent) model under the scenarios of ecological security (ESS), food security (FSS) and comprehensive development (CDS). The model was validated against remote sensing data in 2005. Overall, the accuracy of the CLUE–S model was evaluated at 82.5%. Obtained results show that future cropland changes mainly occur in the Songnen Plain and the Liaohe Plain, forest and grassland changes are concentrated in the southern Lesser Khingan Mountains and the western Changbai Mountains, while the Sanjiang Plain will witness major changes of the wetlands. Our results also show that even though CDS is defined based on the goals of the regional development plan, the ecological service value (ESV) under CDS is RMB 2656.18 billion in 2050. The ESV of CDS is lower compared with the other scenarios. Thus, CDS is not an optimum scenario for eco-environmental protection, especially for the wetlands, which should be given higher priority for future development. The issue of coordination is also critical in future development. The results can help to assist structural adjustments for agriculture and to guide policy interventions in NEC.     

Spatio-temporal differences and factors influencing intensive cropland use in the Huang-Huai-Hai Plain

This study developed a comprehensive system to evaluate the intensity of cropland use and evolution of cropland use in the Huang-Huai-Hai Plain. Delphi-entropy methods were adopted to determine the weight of the index, and the GeoDetector model was established to explore the influencing factors. The results are summarized as follows: (1) The intensity of inputs, degree of utilization, and production increased continuously, but the intensity of continuous conditions experienced an overall decline followed by a rebound towards the end of the study period. The number of counties with high and moderately high intensity increased by 56.8% and 14.6%, respectively, from 1996 to 2011. The number of counties with moderately low and low intensity declined by 35.9 % and 11.9 %, respectively. Areas with significant increases in intensity were mainly distributed in northeast Hebei Province, northwest Shandong Province, and north Jiangsu Province. The intensity is high in northern Jiangsu and Anhui; the output effect remained above moderate intensity mainly near Beijing, Tianjin, Tangshan, and counties in the suburbs of Shijiazhuang. (2) Natural disasters, elevation, slope, and road networks were the main factors influencing the intensity of cropland use in this region, with influence values of 0.158, 0.143, 0.129, and 0.054, respectively. Areas with moderately high and high levels of intensity were distributed in low-lying areas. Uneven distribution of precipitation, seasonal drought, and flood disasters can directly affect the stability index of croplands and reduce the intensity of cropland use. Developed road networks are associated with moderately high intensity. Our results suggest recommendations such as promoting agricultural intensification and large-scale management, promoting the construction of road networks, improving early warning systems for drought and flood disasters, and promoting moderate and intensive use of arable land, and focusing on restoration and sustainable use of cropland.     

徐州都市圈产业结构转型城镇空间响应的时空异质性

整合ESDA和GWR 模型,以徐州都市圈为例,分析了2005~2014年成长型都市圈产业结构转型城镇空间响应强度及其影响因素的时空异质性特征,发现：① 研究期内徐州都市圈产业结构转型城镇空间响应程度不断增强,同期各县域间差异呈持续增大趋势;② 徐州都市圈产业结构转型城镇空间响应强度差异格局的多尺度性特征显著。城乡尺度上,呈现以地级市市区为中心向外围降低的圈层式区域格局;省际边界区域尺度上,呈现向鲁南>皖北>苏北>豫东的区域格局演变趋势;③ 强响应县域主要向京沪铁路沿线地区集聚,城镇空间扩展轴线正在形成。弱响应县域在皖苏、豫皖边界地区集中,形成了产业结构转型城镇空间响应强度较低走廊;④ HH型县域主要集中于地级市市区及其周围地区,LL型县域在豫皖苏边界区域的黄河故道沿线地区集聚,表明南北差异正成为徐州都市圈产业结构转型城镇空间响应强度关联性差异的主要表征;⑤ 徐州都市圈产业结构转型城镇空间响应的主要影响因素作用程度呈现对外开放>经济水平>创新能力>政府调控能力的特征,且空间不均衡性显著。     

中国东部沿海地区四大城市群生态效率评价

东部沿海地区城市群是国家经济发展的战略核心区和国家新型城镇化的主体区之一,其经济—生态可持续发展问题是近年来地理研究领域的前沿主题。首先对城市群生态效率进行定义并将其作为城市群可持续发展测度指标;随后运用传统DEA模型及非期望产出SBM模型,对东部沿海地区四大城市群在2005年、2011年、2014年三个时间截面中的经济效率、生态效率进行比较评价并分析了城市群生态效率时空演变特征;最后通过松弛度分析,为改善沿海地区四大城市群生态效率提供了对应建议。结果表明：① 山东半岛城市群、长三角城市群、珠三角城市群经济综合效率呈先下降后上升的V字型演变格局,而京津冀城市群经济综合效率始终呈下降趋势,2011年前其受纯技术效率影响较大,2011年后受规模效率影响较大;② 京津冀城市群受污染影响带来的效率损失最大,山东半岛城市群相对较小,总体而言,四大城市群生态效率在2005-2011年为下行期,2011-2014为修复期;③ 沿海四大城市群内城市生态效率时空格局具有不同的演化特征,核心城市周边以及沿海沿江地区城市生态效率相对较优,内陆城市则较低;④ 京津冀城市群、长三角城市群、珠三角城市群核心城市资源消耗强度高、经济效益产出高、生态效率高,从整体来看,城市群内多数城市呈污染物排放量下降趋势,污染物治理效果较为明显,环境影响问题有所改善;⑤ 影响东部四大城市群经济生态效率的原因不同,本文从城市群角度进行了差异性分析,并提出了合理化建议。     

一种时空混合插值算法及其应用

针对传统的时空克里格算法的精度受到时空变异函数的影响,而时空变异函数理论模型的选择常受主观因素影响和理论半变异函数局限,没有普适性的建模方法;加之参数较多估计困难,致使插值精度不高的问题,该文提出一种普适性的基于广义回归神经网络自适应时空克里格插值变异函数拟合方法,在此基础上建立了广义回归神经网络与时空克里格结合的新颖时空混合插值算法。通过与传统插值方法在民勤县地下水埋深插值中的比较研究表明,该时空混合插值算法的插值精度显著提高,并且是一个普适性的插值法。     

Empirical modeling and spatio-temporal patterns of urban evapotranspiration for the Phoenix metropolitan area,Arizona

In this study, an empirical model for predicting urban evapotranspiration (ET) is examined for the Phoenix metropolitan area that is in a subtropical desert climate using in situ ET measurements from a local flux tower and remotely sensed moderate-resolution imaging spectroradiometer land products. Annual ET maps of Phoenix are then created for the period from 2001 to 2015 using the empirical model developed. A time-series trend analysis is finally performed using predicted ET maps to discover the spatio-temporal patterns of ET changes during the study period. Results suggest that blue-sky albedo and land surface temperature are two statistically significant variables explanatory to model urban ET for Phoenix. Areas that have experienced significant increases of ET are highly spatially clustered, and are mainly found on the outskirts of the city, while areas of decreasing ET are generally associated with highly developed areas, such as downtown Phoenix.     

一种基于特征-语义的时空数据组织方法

在全面研究时空数据模型理论及构建方法的基础上,本文采用面向特征的数据模型构建方法结合时空语义思想,并引入无缝时空理念,探讨了一种基于特征的无缝时空数据模型构建方法。该模型将地理时空过程特征抽象为特征对象、特征事件、特征过程,不仅能够实现地理实体的空间数据组织及复杂拓扑分析,而且,通过描述特征事件、特征过程及其相互关系实现时空语义表达,进而实现海量信息存储以及高层次时空分析,也为通用性时空数据模型的构建提供了一种新思路。     

地理国(省)情监测时空数据库设计

地理国情监测是测绘部门主动服务科学发展的重要职责和战略任务。本文对陕西省地理国(省)情监测试点的成果进行了系统分析,针对成果管理的需求,结合时空数据库的研究技术,提出了地理国(省)情监测时空数据库建设的技术路线,并对数据库进行了模型设计、概念设计、逻辑设计及管理平台设计。     

Spatio-temporal variations of seismicity in the southern Peru and northern Chile seismic gaps

The spatio-temporal variation of seismicity in the southern Peru and northern Chile seismic gaps is analyzed with teleseismic data (m _b 5.5) between 1965 and 1991, to investigate whether these gaps present the precursory combination of compressional outer-rise and tensional downdip events observed in other subduction zones. In the outer-rise and the inner-trench (0 to 100 km distance from the trench) region, lower magnitude (5.0m _b <5.5) events were also studied. The results obtained show that the gaps in southern Peru and northern Chile do not present compressional outer-rise events. However, both gaps show a continuous, tensional downdip seismicity. For both regions, the change from compressional to tensional regime along the slab occurs at a distance of about 160 km from the trench, apparently associated with the coupled-uncoupled transition of the interplate contact zone. In southern Peru, an increase of compressional seismicity near the interplate zone and of tensional events (5.0m _b 6.3) in the outer-rise and inner-trench regions is observed between 1987 and 1991. A similar distribution of seismicity in the outer-rise and inner-trench regions is observed with earthquakes (m _b <5.5). In northern Chile there is a relative absence of compressional activity (m _b 5.5) near the interplate contact since the sequence of December 21, 1967. After that, only a cluster of low-magnitude compressional events has been located in the area 50 to 100 km from the trench. The compressional activity occurring near the interplate zone in both seismic gaps represents that a seismic preslip is occurring in and near the plate contact. Therefore, if this seismic preslip is associated with the maturity of the gap, the fact that it is larger in southern Peru than in northern Chile may reflect that the former gap is more mature than the latter. However, the more intense downdip tensional activity and the absence of compressional seismicity near the contact zone observed in northern Chile, may also be interpreted as evidence that northern Chile is seismically more mature than southern Peru. Therefore, the observed differences in the distribution of stresses and seismicity analyzed under simple models of stress accumulation and transfer in coupled subduction zones are not sufficient to assess the degree of maturity of a seismic gap.