The freshwater biome gradient framework: predicting macroscale properties based on latitude, altitude, and precipitation

Abstract

Understanding global ecological patterns and processes, from biogeochemical to biogeographical, requires broad‐scale macrosystems context for comparing and contrasting ecosystems. Climate gradients (precipitation and temperature) and other continental‐scale patterns shape freshwater environments due to their influences on terrestrial environments and their direct and indirect effects on the abiotic and biotic characteristics of lakes, streams, and wetlands. We combined literature review, analyses of open access data, and logical argument to assess abiotic and biotic characters of freshwater systems across gradients of latitude and elevation that drive precipitation, temperature, and other variability. We explored the predictive value of analyzing patterns in freshwater ecosystems at the global macrosystems scale. We found many patterns based on climate, particularly those dependent upon hydrologic characteristics and linked to characteristics of terrestrial biomes. For example, continental waters of dry areas will generally be widely dispersed and have higher probability of drying and network disconnection, greater temperatures, greater inorganic turbidity, greater salinity, and lower riparian canopy cover relative to areas with high precipitation. These factors will influence local community composition and ecosystem rates. Enough studies are now available at the continental or global scale to start to characterize patterns under a coherent conceptual framework, though considerable gaps exist in the tropics and less developed regions. We present illustrative global‐scale trends of abiotic, biotic, and anthropogenic impacts in freshwater ecosystems across gradients of precipitation and temperature to further understanding of broad‐scale trends and to aid prediction in the face of global change. We view freshwater systems as occurring across arrays of multiple gradients (including latitude, altitude, and precipitation) rather than areas with specific boundaries. While terrestrial biomes capture some variability along these gradients that influence freshwaters, other features such as, slope, geology, and historical glaciation also influence freshwaters. Our conceptual framework is not so much a single hypothesis as a way to logically characterize patterns in freshwaters at scales relevant to (1) evolutionary processes that give rise to freshwater biodiversity, (2) regulatory units that influence freshwater ecosystems, and (3) the current scope of anthropogenic impacts on freshwaters and the vital ecosystem services they provide.

Global mapping of freshwater nutrient enrichment and periphyton growth potential

“…All models included biomes as predictors. Recent work has argued that freshwater ecosystems are better described by arrays of multiple biophysical gradients such as precipitation, latitude and longitude than areas with specific boundaries like biomes 40 . However, we contest that while biomes are approximations of edaphic characteristics that span large areas, when combined by nutrient-specific variables these combined models produce gradients compatible to those of Dodds, et al 40 .…”

River ecosystem conceptual models and non‐perennial rivers: A critical review

“…Intermittent rivers and ephemeral streams (IRES) have nonflowing dry phases (panels e-g) that are also important in structuring river ecosystems. Blue vs. brown soil/ sediments indicate saturated vs. unsaturated the stream biome gradient concept (Dodds et al, 2015) and the subsequent freshwater biome gradient framework (Dodds et al, 2019) present a framework for how river ecosystems should vary geographically, across continental and global scales and across climate gradients and biomes. These models specifically consider large geographic areas where intermittent or ephemeral flow should occur, with emphasis on the balance between potential and actual evapotranspiration.…”

The role of environmental and spatial factors in the assembly of aquatic insect communities in southern Brazilian temporary ponds

“…Nevertheless, the contribution of climate was spatially structured. The distribution of climate is associated with geography (Dodds et al 2019), and this is likely a contingency of the sampling design of this study, which targeted a study region (southern Brazilian Coastal Plain) that covers a latitudinal gradient of climatic conditions (Villwock & Tomazelli 2006). As for the role of water chemistry, a wide number of studies detected significant association of specific water physicochemical variables with insect composition in ponds, including oxygen content (Batzer & Wissinger 1996;Batzer et al 2004;Stenert et al 2008;Hill et al 2017).…”