9-second gridded continental Australia change in effective area of similar ecological environments (cleared natural areas) for Vascular Plants 1990:2050 MIROC5 RCP 8.5 (CMIP5) (GDM: VAS_v5_r11)

Proportional change in effective area of similar ecological environments for vascular plants as a function of land clearing and change in long term (30 year average) climates between the present (1990 centred) and projected future (2050 centred) under the CanESM2 model (RCP 8.5) based on Generalised Dissimilarity Modelling (GDM) of compositional turnover. This metric describes the combined effects of climate change and land clearing on the area of similar environments to each grid cell as a proportion. Each cell is compared with a sample of 60,000 points in both the present uncleared landscape and an alternative scenario (either present with clearing, or future with clearing), and the pairwise similarities summed (e.g. a completely similar cell will contribute 1, a dissimilar cell 0, with a range of values in between). The contribution of each cell is scaled by the land condition. For each time point, this describes the area of similar environments, which will be low for rare environments and high for widely distributed environments. By dividing the test area by the current area, we are able to quantify the reduction in area as a function of land use/climate change. Values less than one indicate a reduction, values of 1 no change, and values greater than 1 (rare cases in the north) show an increase in similar environments. 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_ ANALYSIS e.g. A_90_CAN85_S or R_90_MIR85_L where BIOLOGICAL GROUP is A: Vascular Plants, M: Vascular Plants, R: Vascular Plants and V: vascular plants基于物种组成周转的广义相异性模型（Generalised Dissimilarity Modelling，GDM），在CanESM2模式（典型浓度路径（Representative Concentration Pathway，RCP）8.5）下，以1990年为基准的当前气候（30年平均长期气候）与以2050年为基准的预估未来气候之间，土地开垦与长期气候变化驱动下维管植物相似生态环境有效面积的比例变化。该指标以比例形式表征了气候变化与土地开垦对每个栅格单元对应相似生态环境面积的综合影响。每个栅格单元分别与当前未开垦景观和两种备选情景（即当前已开垦景观或未来已开垦景观）中的60000个采样点进行比对，将两两间的相似性求和（例如，完全相似的栅格单元得分为1，完全相异的得分为0，其余情况得分介于0到1之间）。每个栅格单元的贡献值会依据土地利用状况进行缩放调整。在每个时间节点下，该指标对应相似生态环境的面积，稀有生境的该值较低，广布生境的该值较高。通过将测试时段的面积除以当前基准面积，可量化土地利用/气候变化导致的面积缩减幅度。当指标值小于1时表示面积缩减，等于1时表示无变化，大于1时（北半球极少数情况）则表示相似生态环境面积有所增加。该指标与其他同类指标一同被开发，用于在大陆及全球尺度下评估气候变化背景下生物多样性保护地系统的效能，相关成果发表于2014年世界自然保护联盟（International Union for Conservation of Nature，IUCN）世界公园大会。其详细说明见于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。数据集提供两种格式：1. 压缩的ESRI浮点栅格数据：包含二进制浮点栅格文件（*.flt）、配套的ESRI头文件（*.hdr）与投影文件（*.prj）。从压缩包解压后，这些文件可导入绝大多数地理信息系统（Geographic Information System，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）：该类数据包可通过ArcGIS解压为带有配套图例的栅格图层。此外，文件9sMethodsSummary.pdf中提供了简短的方法概述，以供进一步参考。本9s系列的图层采用统一命名规则：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，其中生物类群对应如下：A：维管植物、M：维管植物、R：维管植物、V：维管植物。