Integrating environmental variables and WorldView-2 image data to improve the prediction and mapping of Thaumastocoris peregrinus (bronze bug) damage in plantation forests

This study integrated environmental variables together with high spectral resolution WorldView-2 imagery to detect and map Thaumastocoris peregrinus damage in Eucalypt plantation forests in KwaZulu-Natal, South Africa. The WorldView-2 bands, vegetation indices and environmental variables were entered separately into PLS regression models to predict T. peregrinus damage. The datasets were then integrated to test the collective strength in predicting T. peregrinus damage. Important variables were identified by variable importance (VIP) scores and were re-entered into a PLS regression model. The VIP model was then extrapolated to map the severity of damage and predicted T. peregrinus damage with an R² value of 0.71 and a RMSE of 3.26% on an independent test dataset. The red edge and near-infrared bands of the WorldView-2 sensor together with the temperature dataset were identified as important variables in predicting T. peregrinus damage. The results indicate the potential of integrating WorldView-2 data and environmental variables to improve the mapping and monitoring of insect outbreaks in plantation forests. The result is critical for plantation health monitoring using a new sensor which contains important vegetation wavelengths.     

Combining European Earth Observation products with Dynamic Global Vegetation Models for estimating Essential Biodiversity Variables

ABSTRACT

Global, fast and accessible monitoring of biodiversity is one of the main pillars of the efforts undertaken in order to revert it loss. The Group on Earth Observations Biodiversity Observation Network (GEO-BON) provided an expert-based definition of the biological properties that should be monitored, the Essential Biodiversity Variables (EBVs). Initiatives to provide indicators for EBVs rely on global, freely available remote sensing (RS) products in combination with empirical models and field data, and are invaluable for decision making. In this study, we provide alternatives for the expansion and improvement of the EBV indicators, by suggesting current and future data from the European Space Agencýs COPERNICUS and explore the potential of RS-integrated Dynamic Global Vegetation Models (DGVMs) for the estimation of EBVs. Our review found that mainly due to the inclusion of the Sentinel constellation, Copernicus products have similar or superior potential for EBV indicator estimation in relation to their NASA counterparts. DGVMs simulate the ecosystem level EBVs (ecosystem function and structure), and when integrated with remote sensing data have great potential to not only offer improved estimation of current states but to provide projection of ecosystem impacts. We suggest that focus on producing EBV relevant outputs should be a priority within the research community, to support biodiversity preservation efforts.     

基于时间序列叶面积指数稀疏表示的作物种植区域提取

以华北平原黄河以北地区为研究区域,以时间序列叶面积指数LAI(Leaf Area Index)傅里叶变换的谐波特征作为不同作物识别的数据源,利用稀疏表示的分类方法识别2007年—2016年冬小麦、春玉米、夏玉米等主要农作物种植区域。首先利用上包络线Savitzky-Golay滤波分别对2007年—2016年的时间序列MODIS LAI曲线进行重构,进而对重构的年时间序列LAI进行傅里叶变换,以0—5级谐波振幅、1—5级谐波相位作为作物识别的依据,基于各类地物的训练样本,通过在线字典学习算法构建稀疏表示方法的判别字典,对每个待测样本利用正交匹配追踪算法求解稀疏系数,从而计算对应于各类地物的重构误差,根据最小重构误差判定待测样本的作物类型,并对作物识别结果的位置精度进行验证。结果表明,2007年—2016年作物识别的总体精度为77.97%,Kappa系数为0.74,表明本文提出的方法可以用于研究区域主要作物种植区域的提取。     

中国区域MuSyQ叶面积指数产品验证与分析

对多源遥感数据协同生产的2010年—2015年中国区域1 km空间分辨率5天合成的MuSyQ（Multi-source data Synergized Quantitative remote sensing production system）叶面积指数LAI产品进行验证。参考现有的LAI产品（MODIS c5,GLASS LAI）和中国生态系统研究网络部分农田和森林站点可用的LAI地面测量数据,从时空连续性、时空一致性、精度和准确性等方面对中国区域的MuSyQ LAI产品进行定性和定量分析与评价。结果表明：（1） MuSyQ LAI产品在保证精度优于MODIS产品的情况下,时间分辨率和时空连续性均有提高。MuSyQ LAI与其他LAI产品（MODIS c5,GLASS LAI）在整体上有很好的一致性（RMSE=1.0,RMSE=0.81）,但对常绿阔叶林高值处的描述不稳定;（2） 与LAI地面测量数据相比,MuSyQ LAI产品与地面参考图对比结果较好（最高相关性（R²=0.54）和较低总体误差（RMSE=0.96））,其在阔叶作物生长季高值处有些许低估且在某些阔叶林站点有些高估。整体上,MuSyQ LAI产品呈现出较高的精度,可靠的空间分布和连续稳定的时间分布,且对森林LAI的描述具有更可靠的动态范围。     

基于温度植被干旱指数的电网输电线路走廊干旱分析

以湖北省输电线路走廊地区作为研究区,利用2013年1~9月MODIS卫星影像数据,处理得到月尺度的归一化植被指数(Normalized Differential Vegetation Index,NDVI)与地表温度(Land Surface Temperature,LST)数据,构建NDVI-Ts特征空间,计算得到温度植被干旱指数(Temperature Vegetation Dryness Index,TVDI),用TVDI监测结果分析湖北省输电线路走廊区域2013年干旱时空分布情况。结果表明,湖北省输电线路走廊地区TVDI和土壤含水量之间存在显著的负相关,相关系数达到0.525(p0.05),由MODIS卫星影像计算得到TVDI影像可以有效表明湖北省输电线路走廊地区的土壤含水情况。     

扎龙保护区丹顶鹤栖息地适宜性评价

结合TM影像和ENVISAT ASAR(HH/HV)数据,以扎龙保护区丹顶鹤栖息地为研究对象,在分布式定量提取评价因子(植被类型、生境结构、巢下水深、植被盖度、人为干扰)的基础上,建立HSI模型对丹顶鹤栖息地质量进行评价,并根据实测巢址空间分布情况对评价结果进行验证。结果表明:基于主观专家知识建立的HSI模型得到丹顶鹤高适宜栖息地面积为48km2,适宜栖息地面积为265km2,低适宜栖息地面积为385km2,不适宜栖息地面积为1 403km2,结合实测数据验证,得出高适宜、适宜和低适宜栖息地巢址共占实测巢址的92.86%,不适宜栖息地巢址占7.14%。经检验HSI模型对淡水沼泽湿地典型水禽栖息地的质量评价有良好的适用性。     

Experimenting with spaces of encounter: Creative interventions to develop meaningful contact

To-date geographical research on encounters has primarily comprised observation of naturalistic settings (both micro publics and everyday public spaces) or narrative accounts of encounters generated by conventional methods, this paper focuses on a contrived spatial experiment to create meaningful contact across difference. Inspired by, and drawing on insights from, Architecture – a discipline relatively neglected by geographers in recent times – we use a creative form of spatial play to stimulate groups of people to explore their differences and to develop shared understandings. Whereas previous studies have identified the importance of material objects in art projects and home spaces in mediating relations between people, surprisingly little attention has been paid to the physical configuration of space in work on encounters, despite the fact that geography is a spatial discipline. Here, we engage directly with the role of the form and function of space. Our spatial experiments demonstrate how paying attention to the materiality of micro-spaces rather than social relations alone, can provide insights into the generation of positive interactions by contributing to a greater understanding of how meaningful encounters happen, and what can be done to facilitate them. Specifically, by exploring the size and configuration of space, issues of ownership and surveillance, the relationship between primary and secondary space, and aural architecture this research identifies how working together to create a shared private or intimate space – might facilitate a sense of empowerment and the production of social relations characterised by democracy and inclusion.     

基于吸力量测确定膨胀土活动带和裂隙深度

采用M itchell公式和裂隙扩展深度方程两种吸力法确定安康地区膨胀土大气影响深度和裂隙开展深度。其一通过对安康地区两处天然边坡开挖观测井,利用张力计进行不同深度处吸力值的现场量测,根据M itchell提出公式计算大气影响深度;其二根据非饱和土抗拉强度公式,建立膨胀土裂隙扩展深度方程,利用基质吸力量测结果求其理论解。结果表明,安康地区膨胀土吸力变化曲线随深度增加变幅减小,呈波浪式推移。M itchell公式确定安康地区膨胀土的大气影响深度为3.35m以内,裂隙深度方程确定裂隙开展深度为3.063.14m。利用M itchell公式计算大气影响深度与膨胀土断裂理论公式确定的裂隙开展深度结果接近。     

既有地下空间设施安全性耐久性的模糊数学评价研究

本文利用模糊数学综合评价方法,对地下空间设施进行安全性和耐久性水平进行评价。建立反映地下设施安全性和耐久性水平的指标体系,并选定各基本评价因子,按照评价等级给各指标建立打分表,通过技术人员的打分建立评价矩阵以代替隶属函数,再用AHP法建立权重向量,用二级综合评价模型对目标系统进行评价,为地下设施的安全性和耐久性能提供有效的参考信息。     

黄土高原表土花粉与植被覆盖度定量模型的建立及应用

黄土高原是一个气候变化敏感区,亦是一个生态环境脆弱区,更是我国人口-资源-环境矛盾最为集中的区域之一。因此,构建适合于黄土高原表土花粉与植被覆盖度定量模型对了解过去植被覆盖度的演变以及人与环境之间的关系具有重要意义。本工作基于黄土高原443个表土花粉数据和2000~2015年的归一化植被指数（NDVI）,采用逐步回归法（Stepwise）、增长回归树法（BRT）、局部加权加权平均法（LWWA）、加权平均偏最小二乘法（WA-PLS）和最佳类比法（MAT）,结合植被覆盖度（FVC）和年均降水量（MAP）、年均气温（Tann）、1月月均温（T1）、7月月均温（T7）、有效湿度（MAP/ET0）这5个气象要素数据,构建表土花粉与植被覆盖度定量模型;通过普通检验、留一交叉检验（LOO）、自助法检验（Bootstrap）和检验空间自相关性的h-block检验方法对定量模型进行检验,进而筛选出最优模型;最后,利用31个全新世地层花粉数据重建黄土高原过去植被覆盖度,探讨其变化特征。结果表明：1）FVC、MAP、T1、T7和MAP/ET0是黄土高原环境变化的5个重要因子,其中,FVC的第一排序轴特征值/第二排序轴特征值（λ1/λ2）最大（0.47）,单一解释变量最高（8.75）,其与花粉组合的相关性最强（0.66）,可用于构建表土花粉与植被覆盖度定量模型;2）采用Stepwise、BRT、LWWA、WA-PLS和MAT这5种方法分别建立表土花粉-植被覆盖度定量模型,根据观测值与预测值的决定系数（R²）、最大偏差（Max.bias）和预测均方根误差（REMSP）评估构建的模型,结果显示BRT模型表现更优,可用于黄土高原过去植被覆盖度的定量重建;3）全新世FVC重建结果显示,早、中全新世黄土高原FVC较高,其中7.0 cal.ka B.P.时达到峰值（平均值为0.68）;但自4.0 cal.ka B.P.开始,植被覆盖度下降,特别是3.0~2.0 cal.ka B.P.下降明显,平均值低于0.30。通过与研究区内其他气候指标和人类活动强度指标的对比,认为早、中全新世黄土高原植被覆盖度的变化主要受自然气候变化的影响,而晚全新世以来FVC的减少可能更多地与人类活动强度增加有关。