Geostatistical interpolation and aggregation of crop growth model outputs

Many crop growth models require daily meteorological data. Consequently, model simulations can be obtained only at a limited number of locations, i.e. at weather stations with long-term records of daily data. To estimate the potential crop production at country level, we present in this study a geostatistical approach for spatial interpolation and aggregation of crop growth model outputs. As case study, we interpolated, simulated and aggregated crop growth model outputs of sorghum and millet in West-Africa. We used crop growth model outputs to calibrate a linear regression model using environmental covariates as predictors. The spatial regression residuals were investigated for spatial correlation. The linear regression model and the spatial correlation of residuals together were used to predict theoretical crop yield at all locations using kriging with external drift. A spatial standard deviation comes along with this prediction, indicating the uncertainty of the prediction. In combination with land use data and country borders, we summed the crop yield predictions to determine an area total. With spatial stochastic simulation, we estimated the uncertainty of that total production potential as well as the spatial cumulative distribution function. We compared our results with the prevailing agro-ecological Climate Zones approach used for spatial aggregation. Linear regression could explain up to 70% of the spatial variation of the yield. In three out of four cases the regression residuals showed spatial correlation. The potential crop production per country according to the Climate Zones approach was in all countries and cases except one within the 95% prediction interval as obtained after yield aggregation. We concluded that the geostatistical approach can estimate a country’s crop production, including a quantification of uncertainty. In addition, we stress the importance of the use of geostatistics to create tools for crop modelling scientists to explore relationships between yields and spatial environmental variables and to assist policy makers with tangible results on yield gaps at multiple levels of spatial aggregation.     

不同沙丘下梭梭(Haloxylon ammodendron)主根周围土壤特征的差异性研究

为探明沙漠建群种植物个体周围土壤养分和盐分空间分布及成因,对艾比湖湖区边缘三种类型沙丘下梭梭主根周围土壤含水量,电导率,全量养分和速效养分的变化进行了研究。结果表明:1固定性沙丘在表层(0~10 cm)处土壤含水量最小,流动性沙丘和半固定性沙丘在浅层(10~20 cm)处最小,以距离主根面3m处表现最为显著(P0.05)。2流动性沙丘和半固定性沙丘土壤有机质和全氮的结构性和空间自相关性均较弱,固定性沙丘养分(全量养分、速效养分)的结构性则较好。3三种沙丘土壤养分的空间分布不均,主要以条状和斑块状分布,整体上呈现出一定的集聚趋势,其中流动性沙丘和固定性沙丘集聚范围在0~2 m圈层,但纵向集聚范围中,流动性沙丘以浅层(10~20 cm),固定性沙丘以较深层(20~40cm)出现集聚,形成"肥岛"。4流动性沙丘土壤电导率对沙丘的影响较其他各特征因子占主导地位,半固定性沙丘和固定性沙丘养分因子占主导地位。     

佛山岭南天地旧改项目中开放空间的特色分析

近年来,国内出现了不少基于城市老街区改造为商业街区的项目。通过对佛山岭南天地项目中有代表性的广场、街道、建筑等节点进行调研,选取开放空间的3个特色要素——空间形态和尺度,传统装饰元素,植物和水景布置,探析"新天地"模式中开放空间营造的特色手法,包括保持街巷形态和宜人尺度,增强街区公共属性;保护传统建筑构件,利用传统材料、技术;保留古树,并结合植物和水景布置,形成多层次的景观系统等。     

论生态景观吸引力空间异化模型的应用——以江苏环太湖国际旅游区规划为例

以江苏环太湖国际旅游区规划为实验对象,重点探讨生态景观吸引力空间异化过程,即从要素磁场分化开始,经由同质景观间的引力异化,导致同类景观片区间的引力空间异化,最终推导出另一种"同质相斥、异质相吸"的新型生态景观吸引力空间结构。     

基于GIS的土壤肥力质量综合评价——以天然云冷杉针阔混交林为例

以吉林汪清林业局金沟岭林场中41块天然云冷杉针阔混交林样地为对象,采用主成分-聚类分析,结合GIS技术,对该区域土壤肥力质量进行综合评价。结果表明,按主成分-聚类分析结果将41块样地分为4类:第1类土壤肥力质量综合得分为11.17~18.86(优),包括5块样地;第2类土壤肥力质量综合得分为3.01~7.44(良),包括8块样地;第3类土壤肥力质量综合得分为-6.97~1.27(一般),包括24块样地;第4类土壤肥力质量综合得分为-12.40~-9.63(差),包括4块样地。然后采用Arc GIS软件对综合得分进行普通Kriging插值,其标准均方根预测为0.9544,在1的附近,这基本达到插值精度的要求。从生成的研究区土壤肥力质量综合得分空间分布图来看,森林土壤肥力质量由西向东呈现先降低后升高的趋势;由北向南,森林土壤肥力质量变化幅度逐步减小,表明研究区南部土壤肥力质量变化较北部均匀。就研究区的整体土壤肥力质量而言,土壤肥力质量中等以上(优,良,一般)样地数占所研究区样地总数比例为90.24%,表明所研究区森林土壤肥力质量整体处于良好水平。     

The Evolution Characteristics of Spatial Layout of Ancient Chinese Capitals: A Case Study of Sui,Tang and Northern Song Dynasties With Important Changes in the Historical Development of Feudal Society

Imperial city and outer city are the most important differentiation of the spatial structure of ancient Chinese capitals.The relationship between city and Guo changed from the original spatial structure mode of "respecting the west" and "sitting in the west and facing the east" to the spatial structure mode of "sitting in the north and facing the south" and the three outer cities in the east,south and west surrounding the imperial city after the Wei,Jin,Southern and Northern Dynasties,and gradually changed from the original "multi palace" system to the "single palace" system.Finally,a "heavy city" capital spatial structure with the outer city around the imperial city and the imperial city around the palace city,and the central axis of the chessboard format was formed.During the Tang and Song Dynasties,it was a period of great change in the history of feudal society in China.Through the investigation of the evolution characteristics of the spatial form of capital cities in the Tang and Song Dynasties,the track of the transformation of social ideology,political system,economic structure and many other fields in the Tang and Song Dynasties was made clear.     

中国古典园林与戏曲舞台空间布景的共通性

优秀的传统文化是一个民族劳动人民智慧的结晶。随着全球经济一体化的发展，中国传统文化受到西方文化的猛烈冲击，因此以中国古典园林和戏曲艺术的研究为代表的优秀传统文化的研究对中国现代文化发展有着深远意义。笔者通过查阅国内现有的关于古典园林和戏曲舞台空间布景的研究，发现该领域的研究并不丰富。通过对二者空间布局的层次、置陈布势的常用手法和艺术性进行共通性研究，希望对古典园林和戏曲保护提供参考和指导。     

Measuring biogeochemical heterogeneity at the micro scale in soils and sediments

Steep physiochemical gradients and diffusive limitation associated with microscale features such as cracks and pores make soil and sediments remarkably heterogeneous environments, which is reflected on many environmentally important processes. If we are to understand and attempt to control the ecology of the microorganisms which inhabit these environments we must not only characterize their inhabitants, but also the complex biogeochemical landscape they live in. This includes local concentrations of electron acceptors and donors, microbial metabolites and key physical and chemical parameters such as pH and soil structure.To this end, an array of techniques for collecting data at the microscale has been developed, deployed and refined, ranging from microsensor probes to planar sensors. This review provides a general reference for and a critical comparison of microscale techniques available to the fields of soil and sediment microbial ecology. Techniques are evaluated based on their ability to provide spatially resolved data at the microscale, with focus on performance characteristics, potential for repeated measurements, degree of physical disruption they create, and accessibility.Microscale studies have given us many insights, but we outline further progress needed to make the microscale toolkit more accessible and to extend the range of analytes that can be measured simultaneously, so that we may expand our knowledge of the complex environmental microscale heterogeneity and its impact on soil and sediment ecology and functioning.     

基于SPEI_PM指数的渭河流域气象干旱时空演变特征

利用渭河流域25个气象站点1980−2018年月值气象数据集，基于Penman-Monteith蒸散模型计算多个时间尺度的标准化降水蒸散发指数（SPEI），分析渭河流域气象干旱的演变、趋势、影响范围、发生频率和持续时间等时空变化特征，以期为渭河流域防灾减灾管理提供科学依据。结果表明：（1）近39a来渭河流域有明显的干湿周期变化，但整体上呈变干的趋势，干旱时段主要集中在1995−2009年，其中以2000−2009年的干旱站次比最大，平均达到36%，且干旱持续时间最长，约3.6个月，1980−1989年干旱持续时间最短，约1.6个月；（2）渭河流域秋季总体呈湿润变化趋势，而春季和夏季干旱在不断加剧，是区域年际干旱的主要驱动力；（3）渭河流域干旱以危害性较小的轻中旱为主，但2000年前后出现严重及极端干旱的站次相对较多，其中1997年研究区内发生的干旱程度较高，影响范围较广；（4）不同时间尺度各等级干旱发生频率的变化规律表现一致，均呈现出干旱等级越高发生频率越低的态势，且极端干旱在年际尺度内发生次数较为频繁，从空间上看渭河流域东北部是干旱多发区。总之，近39a来渭河流域总体干旱较为严重的时段为2000−2009年，且研究区内干旱呈北重南轻特征，因此北部地区仍需加强防灾管理。     

放牧强度对荒漠草原一年生植物刺穗藜种群特征及空间分布的影响

为探讨不同放牧强度下一年生植物种群特征及空间分布的变化特点及差异,本研究以内蒙古四子王旗短花针茅荒漠草原一年生植物刺穗藜（Chenopodium aristatum）为对象,分析了围封对照（CK）、轻度放牧（Light grazing）、中度放牧（Moderate grazing）和重度放牧（Heavy grazing）下刺穗藜种群特征（密度、单株重、株高、比叶面积、叶片/茎/根系干物质含量、叶片全碳、氮含量）,种群变异性及其空间分布。结果表明：放牧显著影响刺穗藜种群密度（P<0.05）,但对其比叶面积、叶片/根系干物质含量及叶片全碳、氮含量无显著影响;总体而言,放牧使刺穗藜种群密度增加,但对其种群性状影响较小;放牧使得刺穗藜种群相对密度增大（P<0.05）,并造成其种群变异性降低（P<0.05）;对刺穗藜种群空间分布模拟发现,放牧使得刺穗藜种群空间分布均匀,空间异质性降低。在草地利用过程中,一年生植物种群特征及其空间分布可能对群落结构造成影响,对其进行相关研究很有必要。