Abstract
The lack of freshwater-specific environmental information at sufficiently fine spatial grain hampers broad-scale analyses in aquatic biology, biogeography, conservation, and ecology. Here we present a near-global, spatially continuous, and freshwater-specific set of environmental variables in a standardized 1 km grid. We delineate the sub-catchment for each grid cell along the HydroSHEDS river network and summarize the upstream climate, topography, land cover, surface geology and soil to each grid cell using various metrics (average, minimum, maximum, range, sum, inverse distance-weighted average and sum). All variables were subsequently averaged across single lakes and reservoirs of the Global lakes and Wetlands Database that are connected to the river network. Monthly climate variables were summarized into 19 long-term climatic variables following the ‘bioclim’ framework. This new set of variables provides a basis for spatial ecological and biodiversity analyses in freshwater ecosystems at near global extent, yet fine spatial grain. To facilitate the generation of freshwater variables for custom study areas and spatial grains, we provide the ‘r.stream.watersheds’ and ‘r.stream.variables’ add-ons for the GRASS GIS software.
Highlights
Background & SummaryFreshwater habitats cover only 0.1% of Earth’s surface, yet they provide habitat for ~10% of all animal species[1]
Many streams and lakes are considered biodiversity hotspots[2], and understanding the biogeography of freshwater organisms is key for biodiversity conservation and management, especially in the context of ongoing and projected climate and land cover change[3]
Over the past years a number of global high-resolution 1 km data sets have been created to assist the use of spatial modelling, such as gridded climate data from interpolated weather stations (WorldClim6), remote sensing products such as topography (SHuttle Elevation Derivatives at multiple Scales, SRTM7), or Moderate Resolution Imaging Spectroradiometer (MODIS) -derived products such as land cover[8], and derivatives of those
Summary
Freshwater habitats cover only 0.1% of Earth’s surface, yet they provide habitat for ~10% of all animal species[1]. To facilitate a more geographically inclusive and comparable studies in freshwater biodiversity science, we developed near-global 1 km gridded freshwater-specific information comprised of multiple, complementary environmental variables of known relevance for species distributions: climatic (monthly air temperature and precipitation), topographic (elevation and slope), land cover, surface lithological and soil variables (Data Citation 1). This newly developed information is based on the 1 km HydroSHEDS hydrography[12] (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales, www.hydrosheds.org) and accounts for the upstream connectivity within the stream network. A subset of the layers can be visualized online at www.earthenv. org/streams (Data Citation 1)
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