r_90can85_snd: 9-second gridded continental Australia composite ecological change for Reptiles 1990:2050 CanESM2 RCP 8.5 (CMIP5) (GDM: REP_R3_V2)
Composite ecological change as a function of three metrics (the potential degree of ecological change and of disappearing and novel ecological environments) shows where change might be greatest and different types of vulnerability using 30-year climate averages between the present (1990:1976- 2005)...
| Summary: | Composite ecological change as a function of three metrics (the potential degree of ecological change and of disappearing and novel ecological environments) shows where change might be greatest and different types of vulnerability using 30-year climate averages between the present (1990:1976- 2005) and projected future (2050:2036-2065) under the CanESM2 global climate model (RCP 8.5), based on a Generalised Dissimilarity Modelling (GDM) of compositional turnover for reptiles (REP_R3_V2). Wherever the Potential degree of ecological change is scored low, ecological environments can neither be novel nor disappearing and minimal change is expected. But when the Potential degree of ecological change is scored high, a variety of possible types of change can occur depending on whether scores for Novel and/or Disappearing ecological environments are also high. To create a composite view, we assigned each of the three component measures to a colour band in a composite-band raster: local similarity as shades of green (inverted, 1-0 rescaled 0-255); novel as shades of blue (0-1 rescaled 0-255); and disappearing as shades of red (0-1 rescaled 0-255). The three layers can then be mapped simultaneously (red: band 3; green: band 1; blue: band 2) each scaled 0-255 to show the varying degrees of similar, novel and disappearing ecological environments and their combinations. 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 as zipped ESRI tiff grids containing: raster image (*.tif) with associated header (*.tfw) and projection (*.xml) files. After extracting from the zip archive, these files can be imported into most GIS software packages. A readme file describes how to correctly reproduce the colour legend. In ArcGIS, the symbology statistics file can be used: "SND_display.stat.XML". Reproducing RGB composite colours for 3-band raster in ArcGIS: 1. In file properties in ARCGIS, Symbology tab, Load XML "SND_display.stat.XML" 2. RED = BAND_3 (Disappearing) 3. GREEN = BAND_1 (Similarity ) 4. BLUE = BAND_2 (Novel) 5. Always use min-max legend 6. Set each band in the custom range 0-255, mean = 126, std = 0 Layers in this 9s series use a consistent naming convention: BIOLOGICAL GROUP _ FROM BASE TO SCENARIO _ ANALYSIS e.g. A_90CAN85_SND or R_90MIR85_SND where BIOLOGICAL GROUP is A: amphibians, M: mammals, R: reptiles and V: vascular plants and scenario is CAN: CanESM2; MIR: MIROC5 analysis, SND refers to – similarity, novel, disappearing Ecological similarity ranges between 0 and 1: the closer to zero, the greater the potential for compositional change in biodiversity. Each of the three ecological similarity measures were rescaled between 0 and 255 as integers to match the RGB colour scale, but the Potential degree of ecological change measure was inverted first (1-0 rescaled 0-255). Using the Composite Bands tool in ArcGIS 10.2.2, a three-band raster was created with band1 = similarity, S; band 2 = novel, N; and band 3 = disappearing, D. In ArcGIS mapping symbology, each of the three component measures are then assigned to a colour band: RED channel = BAND_3 (Disappearing) GREEN channel = BAND_1 (Similarity) BLUE channel = BAND_2 (Novel) The gamma stretch legend scaling is not used and the min-max legend stretch is applied with statistics defined from the same custom settings for each band: minimum = 0; maximum= 255, mean = 126, std = 0. These settings correctly reproduce the colours. The composite ecological change index derives from the following three measures that are elsewhere described: 1. S, similarity: 9-second gridded continental Australia potential degree of ecological change for Reptiles 1990:2050 CanESM2 RCP 8.5 (CMIP5) (GDM: REP_R3_V2) 2. N, novel: 9-second gridded continental Australia novel ecological environments for Reptiles 1990:2050 CanESM2 RCP 8.5 (CMIP5) (GDM: REP_R3_V2) 3. D, dissimilarity: 9-second gridded continental Australia disappearing ecological environments for Reptiles 1990:2050 CanESM2 RCP 8.5 (CMIP5) (GDM: REP_R3_V2) More detail of the calculations and methods used to derive the individual measures are given in the document “9sMethodsSummary.pdf” provided with the data download. Each of these three measures use the GDM model that is elsewhere described: Generalised dissimilarity model of compositional turnover in reptile species for continental Australia at 9 second resolution using ANHAT data extracted 4 April 2013 (GDM: REP_R3_V2) Climate data. Generalised dissimilarity models were built and projected using climate data that are elsewhere described: a) 9-second gridded climatology for continental Australia 1976-2005: Summary variables with elevation and radiative adjustment b) 9-second gridded climatology for continental Australia 2036-2065 CanESM2 RCP 8.5 (CMIP5): Summary variables with elevation and radiative adjustment A brief summary of the climate downscaling method is given in the document “9sMethodsSummary.pdf” provided with the data download. Further details about the CanESM2 global climate model: Chylek P, Li J, Dubey MK, Wang M and Lesins G (2011) ‘Observed and model simulated 20th century Arctic temperature variability: Canadian Earth System Model CanESM2’, ATMOSPHERIC CHEMISTRY and PHYSICS DISCUSSIONS 11, 22893—22907 doi:10.5194/acpd-11-22893-2011 |
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