title: Climate and landscape influence on indicators of lake carbon cycling through spatial patterns in dissolved organic carbon.
abstract: Freshwater ecosystems are strongly influenced by both climate and the surrounding landscape, yet the specific pathways connecting climatic and landscape drivers to the functioning of lake ecosystems are poorly understood. Here, we hypothesize that the links that exist between spatial patterns in climate and landscape properties and the spatial variation in lake carbon (C) cycling at regional scales are at least partly mediated by the movement of terrestrial dissolved organic carbon (DOC) in the aquatic component of the landscape. We assembled a set of indicators of lake C cycling (bacterial respiration and production, chlorophyll a, production to respiration ratio, and partial pressure of CO2 ), DOC concentration and composition, and landscape and climate characteristics for 239 temperate and boreal lakes spanning large environmental and geographic gradients across seven regions. There were various degrees of spatial structure in climate and landscape features that were coherent with the regionally structured patterns observed in lake DOC and indicators of C cycling. These different regions aligned well, albeit nonlinearly along a mean annual temperature gradient; whereas there was a considerable statistical effect of climate and landscape properties on lake C cycling, the direct effect was small and the overall effect was almost entirely overlapping with that of DOC concentration and composition. Our results suggest that key climatic and landscape signals are conveyed to lakes in part via the movement of terrestrial DOC to lakes and that DOC acts both as a driver of lake C cycling and as a proxy for other external signals.
authors.affiliation: Groupe de Recherche Interuniversitaire en Limnologie et en Environnement Aquatique (GRIL), Département des Sciences Biologiques, Université du Québec à Montréal, Case Postale 8888, succursale Centre-Ville, Montréal, QC, H3C 3P8, Canada.|Department of Fisheries and Wildlife, Michigan State University, 480 Wilson Rd, East Lansing, MI, 48824, USA.
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Lapierre
authors.affiliation: Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA.|Department of Ecology and Environmental Science, Umeå University, 901 87, Umeå, Sweden.
authors.forename: David A
authors.initials: DA
authors.lastname: Seekell
authors.affiliation: Groupe de Recherche Interuniversitaire en Limnologie et en Environnement Aquatique (GRIL), Département des Sciences Biologiques, Université du Québec à Montréal, Case Postale 8888, succursale Centre-Ville, Montréal, QC, H3C 3P8, Canada.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Del Giorgio
mesh_terms: D057486:Carbon Cycle; D002980:Climate; D057231:Climate Change; D017753:Ecosystem; D006812:Humic Substances / Q000032:analysis*; D060106:Lakes / Q000032:analysis*; D008962:Models, Theoretical; D062206:Spatial Analysis
chemical_list: D006812:Humic Substances
keywords: CO
  2; PARAFAC; Respiration; aquatic carbon cycling; boreal; climate; dissolved organic carbon; fluorescence; lake; landscape; spatial structure