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

基于群落组成周转的广义相异度模型（Generalised Dissimilarity Modelling, GDM），在MIROC5模型（RCP 8.5情景）下，哺乳动物相似生态环境有效面积随土地开垦及长期（30年平均）气候（当前以1990年为中心 vs 未来2050年为中心预测）变化的比例变化。

该指标描述了气候变化与土地开垦对每个网格单元相似环境面积的联合影响比例。每个单元均与当前未开垦景观及替代情景（当前开垦或未来开垦）中的60,000个采样点进行比较，并对成对相似度求和（例如，完全相似的单元贡献值为1，完全不相似为0，取值范围介于两者之间）。仅标记为未开垦的单元参与计算。在每个时间点，该指标描述相似环境的面积——稀有环境的面积较低，而广泛分布环境的面积较高。通过将测试面积除以当前面积，可量化土地利用/气候变化导致的面积减少量。取值小于1表示面积减少，等于1表示无变化，大于1（北部罕见）表示相似环境面积增加。

该指标与其他指标一同开发，用于在大陆和全球尺度评估气候变化下保护区系统对生物多样性的有效性，并在2014年世界自然保护联盟（IUCN）世界公园大会上发布。其详细描述见AdaptNRM指南《气候变化对生物多样性的影响：群落水平建模方法》，可在线获取：www.adaptnrm.org。

数据以两种形式提供：
1. 压缩的ESRI浮点网格：包含二进制浮点网格（*.flt）、关联的头文件（*.hdr）及投影文件（*.prj）。从压缩包解压后，这些文件可导入大多数GIS软件包，替换相应头文件后也可作为其他二进制文件格式使用。
2. ArcGIS图层包（*.lpk）：这些包可通过ArcGIS解包为带关联图例的栅格。

此外，文件9sMethodsSummary.pdf中提供了简短的方法摘要，以供进一步参考。Tom HA

本9s系列中的图层采用统一命名规范：生物类群_基准年份_情景年份_分析，例如A_90_CAN85_S或R_90_MIR85_L，其中生物类群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。