Abstract:
The Multiple Element Limitation (MEL) model is used to simulate the recovery of Alaskan arctic tussock tundra to thermal erosion features (TEFs) caused by permafrost thaw and mass wasting. TEFs could be significant to regional carbon (C) and nutrient budgets because permafrost soils contain large stocks of soil organic matter (SOM) and TEFs are expected to become more frequent as climate warms. These simulations deal only with recovery following TEF stabilization and do not address initial losses of C and nutrients during TEF formation. To capture the variability among and within TEFs, we simulate a range of post-stabilization conditions by varying the initial size of SOM pools and nutrient supply rates.
This file contains the results for 25 years of tussock tundra under nitrogen fertilization conditions.
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Methods:
We calibrated the Multiple Element Limitation (MEL IVarc, Rastetter et al., 2013 and Pearce et al., in press) model to Alaskan arctic tundra to simulate recovery of thermal erosion features (TEFs) caused by permafrost thaw and mass wasting. The MEL model was calibrated to match annual C, N, P and water fluxes of tussock tundra on the North Slope of Alaska near Toolik Lake, AK (68° 38'N, 149° 43'W) (see Pearce, in press for details). The calibrated simulates acidic tussock tundra under 2000 climatic conditions, warming, warming and fertilization, fertilization, and decreased solar radiation reasonably well.
In all TEF simulations we assumed that the slope failure caused by the disturbance had stabilized prior to the start of the simulation and that there was no ongoing downslope mass transfer. We cut initial biomass by 90% to reflect the loss of the majority of the standing biomass after a thermal erosion disturbance. We than ran several simulations with varying Phase I and Phase II SOM to reflect a range of possible post-disturbance conditions among and within TEFs. We also simulated conditions that result in a higher availability of nutrients than in the undisturbed tundra used for our calibration.
Table 1: MEL tussock tundra simulations run as part of this study.
Simulation Name Parameter File Driver Database filename
Tussock tundra control MEL.tussock_tundra.v1.0.par Toolik_control.drr MEL_Toolik_tussock_control
Tussock tundra greenhouse MEL.tussock_tundra.v1.0.par Toolik_greenhouse.drr MEL_Toolik_tussock_greenhouse
Tussock tundra greenhouse fertilized MEL.tussock_tundra.v1.0.par Toolik_GH_NP.drr MEL_Toolik_tussock_GH_NP
Tussock tundra shade house MEL.tussock_tundra.v1.0.par Toolik_shade.drr MEL_Toolik_tussock_shade
Tussock tundra NP response MEL.tussock_tundra.v1.0.par Toolik_NP_fertilized.drr MEL_Toolik_tussock_NPfertilized
Baseline TEF MEL.tussock_TEF.v1.0.par Toolik_control.drr MEL_Toolik_tusscock_TEF.regrow
Undisturbed tundra MEL.tussock_tundra.v1.0.par Toolik_Control.drr MEL_Toolik_tussock_undisturbed
Baseline TEF MEL.tussock_TEF.v1.0.par Toolik_Control.drr MEL_Toolik_tusscock_TEF.regrow
Nutrient saturated TEF MEL.tussock_TEF.v1.0_SatNuts.par Toolik_Control.drr MEL_Toolik_tussock_TEF.SatNuts
TEF Analysis: Sim A MEL.tussock_TEF.v1.0.SimA.par Toolik_Control.drr MEL_Toolik_tussock_TEF.SimA
TEF Analysis: Sim B MEL.tussock_TEF.v1.0.SimB.par Toolik_Control.drr MEL_Toolik_tussock_TEF.SimB
TEF Analysis: Sim C MEL.tussock_TEF.v1.0.SimC.par Toolik_Control.drr MEL_Toolik_tussock_TEF.SimC
TEF Analysis: Sim D MEL.tussock_TEF.v1.0.SimD.par Toolik_Control.drr MEL_Toolik_tussock_TEF.SimD
TEF Analysis: Sim E MEL.tussock_TEF.v1.0.SimE.par Toolik_Control.drr MEL_Toolik_tussock_TEF.SimE
TEF Analysis: Sim F MEL.tussock_TEF.v1.0.SimA.par Toolik_50xN.drr MEL_Toolik_tussock_TEF.SimF
TEF Analysis: Sim G MEL.tussock_TEF.v1.0.SimA.par Toolik_50xP.drr MEL_Toolik_tussock_TEF.SimG
TEF Analysis: Sim H MEL.tussock_TEF.v1.0.SimA.par Toolik_50xNP.drr MEL_Toolik_tussock_TEF.SimH
TEF Analysis: Sim I MEL.tussock_TEF.v1.0.SimI.par Toolik_Control.drr MEL_Toolik_tussock_TEF.SimI
TEF Analysis: Sim J MEL.tussock_TEF.v1.0.SimJ.par Toolik_Control.drr MEL_Toolik_tussock_TEF.SimJ
Tussock tundra control MEL.tussock_tundra.v1.0.par Toolik_control.drr MEL_Toolik_tussock_control
Tussock tundra N response MEL.tussock_tundra.v1.0.par Toolik_N_fertilized.drr MEL_Toolik_tussock_Nfertilized
Tussock tundra P response MEL.tussock_tundra.v1.0.par Toolik_P_fertilized.drr MEL_Toolik_tussock_Pfertilized
Tussock tundra NP response MEL.tussock_tundra.v1.0.par Toolik_NP_fertilized.drr MEL_Toolik_tussock_NPfertilized
Aged TEF control MEL.tussock_TEF.v1.0.Yr100.par Toolik_control.drr MEL_Toolik_tussock_TEF100.control
Aged TEF N response MEL.tussock_TEF.v1.0.Yr100.par Toolik_N_fertilized.drr MEL_Toolik_tussock_TEF100.Nfert
Aged TEF P response MEL.tussock_TEF.v1.0.Yr100.par Toolik_P_fertilized.drr MEL_Toolik_tussock_TEF100.Pfert
Aged TEF NP response MEL.tussock_TEF.v1.0.Yr100.par Toolik_NP_fertilized.drr MEL_Toolik_tussock_TEF100.NPfert
Table 2: Percent initial Biomass, debris, and Phase I and Phase II SOM stocks and additional treatments imposed in the TEF simulations.
Simulation Vegetation biomass Debris Phase I SOM Phase II SOM Additional manipulation
Undisturbed tundra 100 100 100 100 none
Baseline TEF 10 75 75 100 none
Nutrient saturated TEF 10 75 75 100 saturating NH4+, PO43-, and DON
TEF Analysis: Sim A 10 75 75 200 none
TEF Analysis: Sim B 10 75 150 100 none
TEF Analysis: Sim C 10 75 150 200 none
TEF Analysis: Sim D 10 75 75 75 none
TEF Analysis: Sim E 10 75 25 100 none
TEF Analysis: Sim F 10 75 75 100 0.75 g N/m2/yr
TEF Analysis: Sim G 10 75 75 100 0.1 g P /m2/yr
TEF Analysis: Sim H 10 75 75 100 0.75 g N/m2/yr
0.1 g P /m2/yr
TEF Analysis: Sim I 10 75 75 100 2x Phase I decomposition
TEF Analysis: Sim J 10 75 75 100 2x Phase II decomposition
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Version Changes:
Nov 2014: Initial dataset. Bonnie Kwiatkowski
Version 2: Changed Distribution URL since the LTER network DAS system is being discontinued. JimL 9Apr2015
Version 3: Minor updates to documentation. Added Models tag and added Project. BK 16Feb22
Version 4: Add code to mirror data set to the Arctic Data Center. BK 16Feb22
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