A dynamic organic soil biogeochemical model for simulating the effects of wildfire on soil environmental conditions and carbon dynamics of black spruce forests

Abstract

Ecosystem models have not comprehensively considered how interactions among fire disturbance, soil environmental conditions, and biogeochemical processes affect ecosystem dynamics in boreal forest ecosystems. In this study, we implemented a dynamic organic soil structure in the Terrestrial Ecosystem Model (DOS‐TEM) to investigate the effects of fire on soil temperature, moisture, and ecosystem carbon dynamics. DOS‐TEM consists of environmental, ecological, disturbance effects, and dynamic organic soil modules. Changes in organic layer thickness are computed from calculated changes in carbon pools following fire and during stand succession. DOS‐TEM was parameterized based on studies reported in the literature and evaluated independently at sites in interior Alaska. This evaluation reveals that (1) DOS‐TEM is capable of accurately simulating the thickness and carbon content of organic soils; and (2) without the dynamic linkage between soil organic thickness and carbon content, the model overestimates soil carbon in deep mineral soil horizons of dry black spruce ecosystems of interior Alaska. Sensitivity tests were performed to investigate issues related to spatial heterogeneity of carbon dynamics including soil drainage and fire frequency. Results show that both soil drainage and fire frequency are important in the carbon dynamics simulated by DOS‐TEM, and should be considered in spatial applications of the model.

The importance of a surface organic layer in simulating permafrost thermal and carbon dynamics

“…This work does not address the impacts of fire on soil thermodynamics and recovery from fire, both of which are strongly influenced by the changes in the SOL (Jafarov et al, 2013). Studies show that wildfires and climate change could substantially alter soil carbon storage (Yuan et al, 2012;Yi et al, 2010). In the current version of the model the topsoil carbon stays in the system and provides resilience to permafrost.…”

Modeling the large-scale effects of surface moisture heterogeneity on wetland carbon fluxes in the West Siberian Lowland

“…where k is a scaling factor that we added to account for the effects of soil pH and redox potential, f T is the Lloyd-Taylor (1994) temperature dependence function, T i , w i , C i , and τ i , are the temperature, volumetric soil moisture, carbon density, and turnover time, respectively, of the i-th pool (Sitch et al, 2003), and f M is a moisture dependence function modified from Yi et al (2010): where w min is 0, w max is 1, w opt is the optimal soil moisture content of 0.5 (at which peak respiration occurs), and r sat is the ratio of the respiration rate at saturation (w = 1) to the peak respiration rate (w = 0.5). k and r sat are calibration parameters.…”

Climate, soil organic layer, and nitrogen jointly drive forest development after fire in the North American boreal zone

“…Other terrestrial ecosystem modeling studies have previously recognized the necessity of integrating feedbacks between fire disturbance and the soil organic layer to capture soil thermal, hydrological, and biogeochemical dynamics in boreal forest ecosystems [Carrasco et al, 2006;Yi et al, 2010;Zhuang et al, 2002]. In work with a dynamic soil organic layer formulation of the Terrestrial Ecosystem Model (TEM), a new empirically parameterized moss layer and multiple soil carbon pools each with distinct porosity, bulk density, and decomposition rates are included [Carrasco et al, 2006;Yi et al, 2010;Zhuang et al, 2002].…”

“…Models of forests in Alaska and central Canada have incorporated dynamic organic layer accumulation [Bona et al, 2016;Carrasco et al, 2006;Yi et al, 2010;Zhuang et al, 2002], NA boreal-specific tree types, and dynamic vegetation [Euskirchen et al, 2014;Euskirchen et al, 2009]. Other models have been used to study the interplay between fires [Yue et al, 2013], soil organic layer depth, and aboveground forest growth within subregions of Canada and Alaska [de Groot et al, 2003;Terrier et al, 2014].…”