We use the Multiple Element Limitation (MEL) model to examine the responses of twelve ecosystems - from the arctic to the tropics and from grasslands to forests - to elevated carbon dioxide (CO2), warming, and 20% decreases or increases in annual precipitation. The ecosystems we simulated include moist acidic tundra, shrub tundra, and wet sedge tundra near Toolik Lake, Alaska, alpine dry meadow tundra near Niwot Ridge, Colorado, restored tallgrass prairie near Kellogg Biological Station, Michigan, native tallgrass prairie at the Konza Prairie, Kansas, upland and lowland boreal forest near Bonanza Creek, Alaska, temperate coniferous forest in HJ Andrews Experimental Forest, Oregon, a northern hardwood forest in Hubbard Brook Experimental Forest, New Hampshire, a transition oak-maple forest in Harvard Forest, Massachusetts, and lowland tropical rainforest near Caxiuanã National Forest, Pará, Brazil.
For each of the twelve sites, we run six 100-year simulations beginning from the calibrated steady state (72 simulations total). The six simulations are: (1) increasing CO2 from 400 to 800 μmol mol-1, (2) warming from current temperatures to current plus 3.5oC, (3) decreasing precipitation from 100% to 80% of the current annual rate, (4) increasing precipitation from 100% to 120% of the current annual rate, (5) doubling of CO2, 3.5oC warming, and 20% decrease in precipitation, and (6) doubling of CO2, 3.5oC warming, and 20% increase in precipitation.
The carbon, nitrogen, phosphorus, and water budgets presented here are used to calibrate the MEL model prior to running the climate change simulations. Citations and calculations for the data presented here are described in the individual site html files included in this dataset.
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We assume each ecosystem is composed of mature vegetation and well-developed soils so we can assume a steady state. We recognize that by making this steady state assumption that we are ignoring biomass accumulation following infrequent disturbances like fire and erosive events that alter soil properties, both of which can be important in some of these biomes. The exceptions to this undisturbed, steady-state approach are the two prairie sites, where we also assume a steady state but with annual burning. We determine peak season values for the organic C, N, and P stocks and for most of the fluxes based on literature values or the steady state assumption. Source data and calculations for all state variables and fluxes listed in the accompanying html files.
This dataset includes the carbon (C), nitrogen (N), phosphorus (P) and water (W) budgets for all the sites in the table below. Data sources and citations are in progress, the table below lists which sites are currently complete.Ecosystem type Field site Site
Source data and citationsArctic Moist-acidic Tussock Tundra Arctic LTER, North Slope, AK ARC-t ARC-t.MELVI.2.8.6.html Arctic Wet Sedge Tundra Arctic LTER, North Slope, AK ARC-w ARC-w.MELVI.2.8.6.html Arctic Shrub Tundra Arctic LTER, North Slope, AK ARC-s ARC-s.MELVI.2.8.6.html Alpine Dry Meadow Tundra Niwot Ridge LTER, Front Range, CO NWT in progress Restored Tall Grass Prairie Kellogg Biological Station LTER, southern MI KBS in progress Native Tall Grass Prairie Konza Prairie LTER, Flint Hills, KS KNZ in progress Boreal Lowland Black Spruce Bonanza Creek LTER, Central AK BNZ-l in progress Boreal Upland Black Spruce Bonanza Creek LTER, Central AK BNZ-u in progress Northern Hard-wood Forest Hubbard Brook LTER, central NH HBR in progress Transiton Oak-Maple Forest Harvard Forest LTER, central MA HFR in progress Temperate Coniferous Forest H. J. Andrews LTER, Cascade Range, OR AND AND.MELVI.2.8.6.html Tropical Rain Forest Caxiuanã National Forest, Pará, Brazil CAX CAX.MELVI.2.8.6.html
Oct 6, 2021: Initial publication BK.
Version 2: Correct arctic site names and coordinates. Add code to mirror data set to the Arctic Data Center. Update keywords. BK 17Feb22
Version 3: Add the MEL summary table to the data set. BK 4Mar2022