title: The hidden season: growing season is 50% longer below than above ground along an arctic elevation gradient.
abstract: There is compelling evidence from experiments and observations that climate warming prolongs the growing season in arctic regions. Until now, the start, peak, and end of the growing season, which are used to model influences of vegetation on biogeochemical cycles, were commonly quantified using above-ground phenological data. Yet, over 80% of the plant biomass in arctic regions can be below ground, and the timing of root growth affects biogeochemical processes by influencing plant water and nutrient uptake, soil carbon input and microbial activity. We measured timing of above- and below-ground production in three plant communities along an arctic elevation gradient over two growing seasons. Below-ground production peaked later in the season and was more temporally uniform than above-ground production. Most importantly, the growing season continued c. 50% longer below than above ground. Our results strongly suggest that traditional above-ground estimates of phenology in arctic regions, including remotely sensed information, are not as complete a representation of whole-plant production intensity or duration, as studies that include root phenology. We therefore argue for explicit consideration of root phenology in studies of carbon and nutrient cycling, in terrestrial biosphere models, and scenarios of how arctic ecosystems will respond to climate warming.
authors.affiliation: Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 981 07, Abisko, Sweden.
authors.forename: Gesche
authors.initials: G
authors.lastname: Blume-Werry
authors.affiliation: Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 981 07, Abisko, Sweden.|Department of Biology, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Wilson
authors.affiliation: Experimental Plant Ecology, Institute of Botany and Landscape Ecology, Greifswald University, D-17487, Greifswald, Germany.
authors.forename: Juergen
authors.initials: J
authors.lastname: Kreyling
authors.affiliation: Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 981 07, Abisko, Sweden.|Research Institute for Nature and Forest INBO, Kliniekstraat 25, 1070, Brussels, Belgium.
authors.forename: Ann
authors.initials: A
authors.lastname: Milbau
mesh_terms: D000388:Air; D000531:Altitude; D001110:Arctic Regions; D018515:Plant Leaves / Q000254:growth & development; D018517:Plant Roots / Q000502:physiology; D012621:Seasons; D012987:Soil; D013696:Temperature
chemical_list: D012987:Soil
keywords: below ground; below-ground; belowground; fine roots; phenology; root growth; root production; sub-Arctic