Browsing by Author "Harms, TK"

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    Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: An expert assessment
    (Environmental Research Letters, 2016-03-07) Abbott, BW; Jones, JB; Schuur, EAG; Chapin, FS; Bowden, WB; Bret-Harte, MS; Epstein, HE; Flannigan, MD; Harms, TK; Hollingsworth, TN; Mack, MC; McGuire, AD; Natali, SM; Rocha, AV; Tank, SE; Turetsky, MR; Vonk, JE; Wickland, KP; Aiken, GR; Alexander, HD; Amon, RMW; Benscoter, BW; Bergeron, Y; Bishop, K; Blarquez, O; Bond-Lamberty, B; Breen, AL; Buffam, I; Cai, Y; Carcaillet, C; Carey, SK; Chen, JM; Chen, HYH; Christensen, TR; Cooper, LW; Cornelissen, JHC; De Groot, WJ; Deluca, TH; Dorrepaal, E; Fetcher, N; Finlay, JC; Forbes, BC; French, NHF; Gauthier, S; Girardin, MP; Goetz, SJ; Goldammer, JG; Gough, L; Grogan, P; Guo, L; Higuera, PE; Hinzman, L; Hu, FS; Hugelius, G; Jafarov, EE; Jandt, R; Johnstone, JF; Karlsson, J; Kasischke, ES; Kattner, G; Kelly, R; Keuper, F; Kling, GW; Kortelainen, P; Kouki, J; Kuhry, P; Laudon, H; Laurion, I; MacDonald, RW; Mann, PJ; Martikainen, PJ; McClelland, JW; Molau, U; Oberbauer, SF; Olefeldt, D; Paré, D; Parisien, MA; Payette, S; Peng, C; Pokrovsky, OS; Rastetter, EB; Raymond, PA; Raynolds, MK; Rein, G; Reynolds, JF; Robards, M; Rogers, BM; Schdel, C; Schaefer, K; Schmidt, IK; Shvidenko, A; Sky, J; Spencer, RGM; Starr, G; Striegl, RG; Teisserenc, R; Tranvik, LJ; Virtanen, T; Welker, JM; Zimov, S
    As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.
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    Macrosystems ecology: Understanding ecological patterns and processes at continental scales
    (Frontiers in Ecology and the Environment, 2014-02-01) Heffernan, JB; Soranno, PA; Angilletta, MJ; Buckley, LB; Gruner, DS; Keitt, TH; Kellner, JR; Kominoski, JS; Rocha, AV; Xiao, J; Harms, TK; Goring, SJ; Koenig, LE; McDowell, WH; Powell, H; Richardson, AD; Stow, CA; Vargas, R; Weathers, KC
    Macrosystems ecology is the study of diverse ecological phenomena at the scale of regions to continents and their interactions with phenomena at other scales. This emerging subdiscipline addresses ecological questions and environmental problems at these broad scales. Here, we describe this new field, show how it relates to modern ecological study, and highlight opportunities that stem from taking a macrosystems perspective. We present a hierarchical framework for investigating macrosystems at any level of ecological organization and in relation to broader and finer scales. Building on well-established theory and concepts from other subdisciplines of ecology, we identify feedbacks, linkages among distant regions, and interactions that cross scales of space and time as the most likely sources of unexpected and novel behaviors in macrosystems. We present three examples that highlight the importance of this multiscaled systems perspective for understanding the ecology of regions to continents. © The Ecological Society of America.