9-second gridded continental Australia change in effective area of similar ecological environments (cleared natural areas) for Mammals 1990:2050 MIROC5 RCP 8.5 (CMIP5) (GDM: MAM_R2)

Proportional change in effective area of similar ecological environments for Mammals 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 MIROC5 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). Only cells which are flagged as uncleared contribute. 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.Tom HA 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: Mammals, M: mammals, R: reptiles and V: vascular plants基于以物种组成周转为基础的广义相异性模型（Generalised Dissimilarity Modelling, GDM），本数据集展示了在MIROC5模型（典型浓度路径RCP 8.5）下，以1990年为基准的当前时段与以2050年为基准的预测未来时段之间，土地开垦与长期（30年平均）气候变化共同作用下，哺乳动物相似生态环境有效面积的比例变化。 该指标量化了气候变化与土地开垦对各栅格单元相似生境面积的综合影响，以比例形式呈现。将每个栅格单元分别与当前未开垦景观及两种替代情景（当前已开垦景观、未来已开垦景观）中的60000个采样点进行比对，累加两两间的相似性得分（例如完全相似的栅格得分为1，完全不相似得分为0，中间值对应不同相似程度）。仅标记为未开垦的栅格单元参与计算。 对于每个时间节点，该指标反映了相似生境的总面积：稀有生境对应较低数值，广布生境对应较高数值。通过将测试时段的生境面积除以基准当前时段的面积，可量化土地利用/气候变化引发的生境面积缩减比例：数值小于1代表面积缩减，等于1代表无变化，大于1的情况（仅在北部少数区域出现）则代表相似生境面积有所增加。 该指标与其他同类指标共同开发，用于在大陆及全球尺度下评估气候变化背景下保护区系统对生物多样性的保护效能，相关成果曾在2014年世界自然保护联盟（IUCN）世界公园大会上发布。其详细说明见于《AdaptNRM指南：气候变化对生物多样性的影响：群落级建模方法》，可通过在线链接www.adaptnrm.org获取。 数据集以两种形式提供： 1. 压缩的ESRI浮点栅格数据集：包含二进制浮点栅格文件（*.flt）、关联的ESRI头文件（*.hdr）与投影文件（*.prj）。从压缩包解压后，此类文件可导入绝大多数地理信息系统（GIS）软件，也可通过替换对应头文件的方式，作为其他二进制格式文件使用。 2. ArcGIS图层包（*.lpk）：此类文件可通过ArcGIS软件解压为带关联图例的栅格图层。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系列中的Tom HA图层采用统一命名约定：命名格式为「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代表哺乳动物（Mammals）、M代表哺乳动物、R代表爬行动物、V代表维管植物。