9-second gridded continental Australia need for assisted dispersal (50% similarity) for Vascular Plants 1990:2050 CAN ESM2 RCP 8.5 (CMIP5) (GDM: VAS_v5_r11)

Need for assisted dispersal for Vascular Plants as a function of change in long term (30 year average) climates between the present (1990 centred) and projected future (2050 centred) under the CAN ESM2 model (RCP 8.5) based on Generalised Dissimilarity Modelling (GDM) of compositional turnover. The distance to the nearest grid cell with ecological similarity of at least 0.5 is given.This metric describes the nature of the projected 2050 centred future environmental conditions for each 9s grid square. Using a Generalised Dissimilarity Model of compositional turnover (the effects of changing environment on changing species), each future location is compared with the continent in the present. For each cell, the metric looks out to all other cells in the continent, and records the ecological similarity of the future state of the cell to the most similar cell in the present. A value of 1 indicates that the future environment is similar to a current location in the present, and perfect analogue can found somewhere in Australia. A value of 0 indicates that the most similar environment to be found in the present is ecologically so different that we would expect no species in common, i.e. there are no current analogues for this environment; it is novel. Intermediate values show how ecologically similar the most similar cell is. However, no weight is given to the proximity of the most similar cell. The environment may be similar, but the cells thousands of kilometres apart.This metric was developed along with others for use in an assessment of the efficacy of the protected area system for biodiversity under climate change at continental and global scales, presented at the IUCN World Parks Congress 2014. It is described in the AdaptNRM Guide “Implications of Climate Change for Biodiversity: a community-level modelling approach”, available online at: www.adaptnrm.org. Data are provided in two forms:1. Zipped ESRI float grids: Binary float grids (*.flt) with associated ESRI header files (*.hdr) and projection files (*.prj). After extracting from the zip archive, these files can be imported into most GIS software packages, and can be used as other binary file formats by substituting the appropriate header file.2. ArcGIS layer package (*.lpk): These packages contain can be unpacked by ArcGIS as a raster with associated legend.Additionally a short methods summary is provided in the file 9sMethodsSummary.pdf for further information.Layers in this 9s series use a consistent naming convention:BIOLOGICAL GROUP _ FROM BASE_ TO SCENARIO_ ANALYSISe.g. A_90_CAN85_S or R_90_MIR85_Lwhere BIOLOGICAL GROUP is A: amphibians, M: mammals, R: reptiles and V: vascular plantsLineage: Need for assisted dispersal was calculated calculated using the highly parallel bespoke CSIRO Muru software running on a LINUX high-performance-computing cluster, taking GDM model transformed environmental grids as inputs. The distance to the nearest future cell with an ecological similarity > 0.5 to the present cell was calculated. More detail of the calculations and methods are given in the document “BiodiversityModellingMethodsSummary.pdf” provided with the data download. GDM Model: Generalised dissimilarity model of compositional turnover in Vascular Plant species for continental Australia at 9 second resolution using ANHATdata extracted 2013 (GDM: VAS_v5_r11)Climate data. Models were built and projected using:a) 9-second gridded climatology for continental Australia 1976-2005: Summary variables with elevation and radiative adjustmentb) 9-second gridded climatology for continental Australia 2036-2065 CAN ESM2 RCP 8.5 (CMIP5): Summary variables with elevation and radiative adjustment

本数据集聚焦维管植物（vascular plants）的辅助扩散需求，该需求基于以1990年为基准的当前气候，与CAN ESM2模式（RCP 8.5）下以2050年为基准的未来长期（30年平均）气候变化之间的函数关系，通过物种组成更替的广义相异度建模（Generalised Dissimilarity Modelling, GDM）构建。
本数据集给出了生态相似性不低于0.5的最近网格单元的距离。
该指标用于描述每个9秒分辨率网格单元对应的以2050年为基准的未来环境特征。通过刻画环境变化对物种组成变化影响的广义相异度建模（GDM），我们将每个未来样点与当前的澳大利亚大陆区域进行对比。针对每个网格单元，该指标会遍历大陆范围内的所有其他单元，记录该单元未来状态与当前最相似单元的生态相似性。相似性值为1表示未来环境与当前某一位置的环境高度相似，可在澳大利亚境内找到完美的类似环境；值为0则表示当前所能找到的最相似环境在生态上差异极大，以至于预计不存在共有物种，即该环境无当前类似物，属于全新环境；中间值则体现了最相似单元的生态相似程度。但该指标未考虑最相似单元的空间邻近性，即便环境相似，两个单元之间可能相距数千公里。
该指标与其他指标一同被开发，用于在大陆及全球尺度下评估气候变化下生物多样性保护区系统的有效性，相关成果曾在2014年世界自然保护联盟（IUCN）世界公园大会上展示。相关描述见于《AdaptNRM指南："Implications of Climate Change for Biodiversity: a community-level modelling approach"》，可通过网址www.adaptnrm.org在线获取。
数据集以两种形式提供：
1. 压缩的ESRI浮点网格：包含二进制浮点网格文件（*.flt）、关联的ESRI头文件（*.hdr）与投影文件（*.prj）。从压缩包解压后，这些文件可导入多数地理信息系统（GIS）软件，也可通过替换对应头文件的方式作为其他二进制文件格式使用。
2. ArcGIS图层包（*.lpk）：此类包可由ArcGIS解压为带有配套图例的栅格数据。
此外，数据集中附带了简短的方法总结文件9sMethodsSummary.pdf，以供进一步查阅。
本9秒分辨率系列数据集的图层采用统一命名规范：
生物类群_基准时段_情景_分析类型
例如：A_90_CAN85_S 或 R_90_MIR85_L
其中生物类群的编码规则为：A代表两栖类，M代表哺乳类，R代表爬行类，V代表维管植物。
数据生成溯源：辅助扩散需求通过运行于Linux高性能计算集群的高度并行化定制化CSIRO Muru软件计算得出，以经GDM模型转换的环境网格数据作为输入。本研究计算了当前网格单元与生态相似性大于0.5的最近未来网格单元之间的距离。更多计算细节与方法可参见数据下载包中附带的《BiodiversityModellingMethodsSummary.pdf》文件。
GDM模型：
以2013年提取的ANHAT数据为基础，针对澳大利亚大陆9秒分辨率的维管植物物种组成更替构建广义相异度模型（GDM: VAS_v5_r11）。
气候数据：模型构建与投影使用以下数据集：
a) 1976-2005年澳大利亚大陆9秒网格化气候数据集：包含海拔与辐射校正的汇总变量
b) 2036-2065年澳大利亚大陆9秒网格化气候数据集（CAN ESM2 RCP 8.5，CMIP5）：包含海拔与辐射校正的汇总变量