Landscape determinants of lake benthic and pelagic primary production

Global change affects gross primary production (GPP) in benthic and pelagic habitats of northern lakes by influencing catchment characteristics and lake water biogeochemistry. However, how changes in key environmental drivers manifest and impact total (i.e., benthic + pelagic) GPP and the partitioning of total GPP between habitats, here represented by the benthic share (autotrophic structuring) is unclear. This dataset presentes compiled data on summer gross primary productivity (GPP) in benthic and pelagic habitats sampled in situ between 2005-2017, together with water chemistry, from 26 shallow lakes (maximum 3.7-15.8 m deep) from three different sites in northern Sweden, located in the Arctic (Norrbotten), subarctic (Jämtland) and boreal (Västerbotten) biomes. The three study regions have variable elevation gradients and vegetation cover. The study lakes cover a wide range of DOC (1.5-16.3 mg·L^-1) and accompanied water physico-chemistry.

Using this dataset, we investigate how catchment properties (air temperature, land cover, hydrology) affect lake physico-chemistry and patterns of total GPP and autotrophic structuring. We find that total GPP was mostly light limited, due to high dissolved organic carbon (DOC) concentrations originating from catchment soils with coniferous vegetation and wetlands, which is further promoted by high catchment runoff. In contrast, autotrophic structuring related mostly to the relative size of the benthic habitat, and was potentially modified by CO₂ fertilization. Across Arctic and subarctic sites, DIC and CO₂ were unrelated to DOC, indicating that external inputs of inorganic carbon can influence lake productivity patterns independent of terrestrial DOC supply. By comparison, DOC and CO₂ were correlated across boreal lakes, suggesting that DOC mineralization acts as an important CO₂ source for these sites.

Our results underline that GPP as a resource is regulated by landscape properties, and is sensitive to large-scale global changes (warming, hydrological intensification, recovery of acidification) that promote changes in catchment characteristics and aquatic physico-chemistry. Our findings aid in predicting global change impacts on autotrophic structuring, and thus community structure and resource use of aquatic consumers in general. Given the similarities of global changes across the Northern hemisphere, our findings are likely relevant for northern lakes globally.