9-second gridded continental Australia potential degree of ecological change for Reptiles 1990:2050 CanESM2 RCP 8.5 (CMIP5) (GDM: REP_r3_v2)

Potential degree of ecological change in Reptiles as a function of 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 change in long term average environmental conditions at a single location (9s grid square) from the present (1990 centred) to a 2050 centred future, scaled in terms of its expected effects on the turnover of species. Compositional turnover patterns in amphibian species across continental Australia were derived using Generalised Dissimilarity Modelling (GDM). These models use best-available biological data extracted from the Atlas of Living Australia (ALA) in 2013, and spatial environmental predictor data compiled at 9 second resolution. GDM-scaled environmental grids were used as the basis for pairwise cell comparisons across space and time using the highly parallel CSIRO Muru software to derive the potential degree of ecological change. Each location is compared with its future state. The difference in environment is presented as an expected ecological similarity, ranging from 1 (completely similar) to 0, for which we would expect no species in common. If this environmental difference was observed in a different spatial location within the present, we would expect to observe such a difference if we visited both sites. 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: Reptiles, M: Reptiles, R: reptiles and V: vascular plantsLineage: Potential degree of ecological change was 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 similarity of each cell in the present to its future state was calculated. More detail of the calculations and methods are given in the document “9sMethodsSummary.pdf” provided with the data download. GDM Model: \tGeneralised dissimilarity model of compositional turnover in reptile species for continental Australia at 9 second resolution using ALA data extracted 28 February 2014 (GDM: REP_r3_v2)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 CanESM2 RCP 8.5 (CMIP5): Summary variables with elevation and radiative adjustment

基于物种组成更替的广义差异模型（Generalised Dissimilarity Modelling, GDM），本指标表征以1990年为中心的当前气候与以2050年为中心的未来气候（采用CanESM2模式（RCP 8.5）情景）间的长期（30年平均）气候变化所对应的爬行动物潜在生态变化程度。

本指标描述单个位点（9秒栅格单元）的长期平均环境条件从以1990年为中心的当前时段到以2050年为中心的未来时段的变化，并以其对物种更替的预期效应进行标准化。澳大利亚大陆两栖动物的物种组成更替模式通过广义差异模型（GDM）推导得到，所用数据为2013年从澳大利亚生物图鉴（Atlas of Living Australia, ALA）获取的最优生物数据，以及分辨率为9秒的空间环境预测因子数据。研究采用高度并行化的CSIRO Muru软件，以经GDM标准化的环境栅格为基础，开展跨时空的成对栅格单元对比，从而计算得到潜在生态变化程度。每个位点均与其未来状态进行比对，环境差异以预期生态相似度表示，取值范围为1（完全相似）到0（预期无共有物种）。若在当前时段的不同空间位点间观测到该类环境差异，则当同时造访这两个位点时，即可观测到对应物种组成差异。

本指标与其他同类指标一同开发，用于评估大陆及全球尺度下气候变化对生物多样性保护区系统的有效性，相关成果发表于2014年世界自然保护联盟（IUCN）世界公园大会。该指标的详细说明载于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数据使用。
2. ArcGIS图层包（*.lpk）：该类数据包可通过ArcGIS解压为带配套图例的栅格数据。

此外，数据附带的9sMethodsSummary.pdf文件提供了方法学概要，可供读者查阅更多细节。

本9秒分辨率系列栅格采用统一命名规则：
`生物类群_基准时段_情景_分析类型`
示例：A_90_CAN85_S 或 R_90_MIR85_L
其中生物类群的取值为：A、M、R代表爬行动物，V代表维管植物。

数据溯源：潜在生态变化程度通过运行于Linux高性能计算集群的高度定制化并行CSIRO Muru软件计算得到，输入数据为经GDM模型转换的环境栅格。研究计算了当前时段每个栅格单元与其未来状态的相似度，详细计算过程与方法学说明见数据下载附带的9sMethodsSummary.pdf文件。

GDM模型：
基于2014年2月28日获取的澳大利亚生物图鉴（ALA）数据，构建的澳大利亚大陆9秒分辨率爬行动物物种组成更替广义差异模型（模型标识：REP_r3_v2）。
气候数据：模型构建与投影采用以下数据集：
a) 1976-2005年澳大利亚大陆9秒分辨率栅格气候数据集：包含经海拔与辐射校正的汇总变量
b) 2036-2065年澳大利亚大陆9秒分辨率栅格气候数据集（CanESM2 RCP 8.5情景，CMIP5）：包含经海拔与辐射校正的汇总变量