Topography-based metrics for climate-change microrefugia: topodiversity, glaciers, wetlands, cool slopes in British Columbia (Version 2.1)

Suggested citation Kehm, G. 2026. Topography-based metrics for climate-change microrefugia: topodiversity, glaciers, wetlands, cool slopes in British Columbia (Version 3.0). Place of publication: GKA Geographic Solutions Inc., Vancouver, BC. doi: https://doi.org/10.5281/zenodo.14708617 Map example visualizations A) Macro Landform of British Columbia map B) Topodiversity of British Columbia map Summary The physical landscape plays a significant role in determining where biodiversity can exist. Heterogeneity in physical combinations of landform, slope, soils, hydrology, geology, and altitude can result in a diversity of localized climates such that species can make smaller spatial adjustments to track suitable habitat and climatic conditions (Lawrence A., et al., 2021; Carroll et al., 2017; Littlefield et al., 2017). While abiotic, physical diversity focuses on the non-living aspects of the Earth, it is closely linked to biodiversity, as the abiotic foundation plays a key role in the distribution and survival of species. Due to the slow, enduring qualities of high physical diversity environments, conserving large areas of high physical diversity can maintain suitable climatic conditions for species survival (Hannah., et al. 2007; Loarie., et al., 2009). The physical diversity includes both topodiversity and geodiversity. Both terms are often used interchangeably; however, they describe different combinations of physical attributes (i.e., substrate, elevation) with implications for creating diversity indices and biodiversity conservation decisions. Topodiversity is the focus of these data products and refers to the variety and abundance of landforms and terrain, including hydrological complexes like wetlands, lakes, rivers, and streams. Landform examples include islands, north-facing sideslopes, toe slopes, cliffs, and ridgelines. Topodiversity metrics are useful in identifying climate-change microrefugia for conservation planning and management. Topographic diversity is highly correlated with reduced climate change impacts in protected areas worldwide (Lawrence, A., 2021). The conservation of some ecologically important taxa, such as bee pollinators, may be aided for site prioritization using topodiversity metrics (Doherty, K., 2021). For conceptual clarity and background context, it is useful to distinguish between topodiversity, the focus of these data, and geodiversity, which can also be referred to as ‘enduring features’. Geodiversity encompasses the natural range of geological, geomorphological, landform, pedological (soils), and hydrological features and processes. This is an inclusive term for a matrix of landscape attributes that support biodiversity, broadly capturing ecologically meaningful groupings of geology, landform, and altitude. Geodiversity examples include ‘mid-elevation toe slope on calcareous bedrock’ or ‘low-elevation dry flats on thick glacial fluvial sediment’. Geodiversity is useful as an input into processes for identifying new conservation lands, assessing the representative biodiversity contributions of existing conservation lands, and stratifying field sampling designs. Both topodiversity and geodiversity analyses, supported by the climate-change refugial characteristics of cooler landform types, can support the resilience of conservation planning decisions and designations over time. Additional benefits of applying a topodiversity analysis include: * Inform decisions and management of resource development projects in ‘special management areas’ by supporting precautionary principles of minimizing environmental impacts.* Create additional information for input into spatial analyses identifying important priority areas in land use or watershed-based planning processes.* Provide additional support for decision-makers when pursuing land conversion processes in specific areas. The topodiversity dataset is based on the Gini-Simpson Diversity Index (GSDI), which is the oldest and simplest method for measuring biodiversity. It is relatively less sensitive to richness and thus rare patch types, as it highlights relative species abundance. The Fragstats V3.4 beta-64 software (Serena Pallecchi, re. McGarigal, K., and B. J. Marks) was used to generate the index from a macro landform model. The glaciers, wetlands, and cooler northern slopes are landform types reclassified from the Macro landform of British Columbia data layer. The cooler landform types include glaciers, wetlands, cooler cliff, cool bedrock slope, cool steep slope, and cool upper and mid-side slope. Disclaimer These data are proxies for topographic climate-change microrefugia. Actual microclimates also depend on vegetation, canopy structure, hydrology, substrate, and local weather. High topodiversity does not necessarily imply observed thermal buffering. The selected moving-window scale affects results. The data are also an example of a landscape metric and an approach to capturing the role of physical landscape drivers in the landscape that influence biodiversity. As such, care must be taken in understanding the limitations of the models, testing against local knowledge and other spatial data themes, and the thoughtful application to avoid an overinterpretation in applied uses. These data are available for use as is, and without any warranty, claim of correctness, completeness, or utility. Versioning Version 2.0 of the topodiversity index is based upon a Shannon Diversity Index (SHDI), which is effective for tracking rarity within biotic samples. Version 2.1 of the topodiversity index is based upon a Gini-Simpson Diversity Index (GSDI). GSDI also originates from biological diversity research methods and is applied here to physical diversity as it appears to improve classification scalability across the province of British Columbia (95 million hectares) and at larger map scales. Raster Parameters File format: All raster files packaged as GeoTIFF.ZIP archives and ArcGIS Pro layer packages sharing the same projection and snapped to the Macro land form layer. Projection: EPSG:3005 NAD83 / BC Albers (Meters); Type: PROJECTED_CRS; WGS84 Bounds: -139.04, 48.25, -114.08, 60.01; Scope: Province-wide spatial data management; Area: Canada - British Columbia. Projection method name: BC Albers NAD83 Raster cell size: 100m x 100m native resolution snapped to the Macro landform raster File Manifest 1. Glaciers, wetlands, cooler slopes in BC_Kehm.lpkx is the ArcGIS Pro layer package containing the legend and attribute table. 2. Glaciers, wetlands, cooler slopes in BC_Kehm – geotiff.zip includes the GeoTIFF image files as a single raster layer that includes cool side slopes, steep slopes, bedrock slopes, cliffs, wetlands, and glaciers. Glaciers, wetlands, cooler slopes in BC – Kehm.tiff (analysis image) Glaciers, wetlands, cooler slopes in BC – Kehm.tfw (World file) Glaciers, wetlands, cooler slopes in BC – Kehm.vat (attribute table) README.PDF (the data description) 3. Topodiversity in British Columbia V2.1 – Kehm.lpkx is the ArcGIS Pro layer package that includes a classified legend and attribute table. 4. Topodiversity in British Columbia V2_1 – Kehm.zip includes the GeoTIFF image files Topodiversity in British Columbia V2_1 – Kehm.tiff (analysis image) Topodiversity in British Columbia V2_1 – Kehm.tfw (World file) Topodiversity in British Columbia V2_1 – Kehm.vat (attribute table) Topodiversity in British Columbia V2_1 – Kehm.png (visualization image) README.PDF (data description) 5. BC_hillshade.lpkx is the ArcGIS Pro layer package of a shaded topographic relief image for visualization 6. BC_hillshade.zip includes the GeoTIFF image of shaded topographic relief (georeferenced visualization image) 7. Macro landform and topodiversity map_Kehm.png (visualization image) Approach The macro landform raster was used as the primary input layer to Fragstats software. A Gini-Simpson Diversity Index (GSDI) was calculated using the Fragstats 4.3beta-64 application (Serena Pallecchi, ref. McGarigal, K., and B. J. Marks, Fragstats V4.3). The GSDI is the oldest and simplest method to measure biodiversity. It is relatively less sensitive to richness and thus rare patch types, as it highlights relative species abundance. Candidate search window distances were run and reviewed for the GSDI and SHDI. Search radii included the following distances (meters): 200, 300, 350, 400, 1000. The sampling strategy was consistent and included an eight-cell square neighbourhood moving window without kernel weighting. The eight-cell window (instead of a four-cell window) includes all sides and diagonals of the search window and adjacent macro landforms. The eight cells are equivalent to 800 meters and did a reasonable job of capturing the variety of macro landform types across mountains, plateaus, and lowlands. A regional or subregional topodiversity analysis could use a window size appropriate to that landscape and its landform variety. The GSDI and SHDI results were qualitatively reviewed by visual examination and comparison with the macro landform and orthoimagery. The examinations were of locations representing lowlands, plateaus, and mountainous areas across British Columbia. Representation of adjacent landforms, continuity, and avoidance of overgeneralization in high topodiversity areas were important considerations. Consideration was also given to how well it can be expected to capture the topodiversity in a highly varied province, with a very large project area (95 million hectares), and the fractal nature of the topodiversity metric itself. Finally, a use-case goal of having province-wide to regional scalability for the data was considered. The GSDI using a 1000m search radius was selected. While not recognized for capturing rarity as well as the SHDI in biological studies, it held consistency across a large and highly varied terrain. The values ranged from 0.0 to 1.0, which aids in interpretation. 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