Novel coupled permafrost–forest model (LAVESI–CryoGrid v1.0) revealing the interplay between permafrost, vegetation, and climate across eastern Siberia

Abstract

Abstract. Boreal forests of Siberia play a relevant role in the global carbon cycle. However, global warming threatens the existence of summergreen larch-dominated ecosystems, likely enabling a transition to evergreen tree taxa with deeper active layers. Complex permafrost–vegetation interactions make it uncertain whether these ecosystems could develop into a carbon source rather than continuing atmospheric carbon sequestration under global warming. Consequently, shedding light on the role of current and future active layer dynamics and the feedbacks with the apparent tree species is crucial to predict boreal forest transition dynamics and thus for aboveground forest biomass and carbon stock developments. Hence, we established a coupled model version amalgamating a one-dimensional permafrost multilayer forest land-surface model (CryoGrid) with LAVESI, an individual-based and spatially explicit forest model for larch species (Larix Mill.), extended for this study by including other relevant Siberian forest species and explicit terrain. Following parameterization, we ran simulations with the coupled version to the near future to 2030 with a mild climate-warming scenario. We focus on three regions covering a gradient of summergreen forests in the east at Spasskaya Pad, mixed summergreen–evergreen forests close to Nyurba, and the warmest area at Lake Khamra in the southeast of Yakutia, Russia. Coupled simulations were run with the newly implemented boreal forest species and compared to runs allowing only one species at a time, as well as to simulations using just LAVESI. Results reveal that the coupled version corrects for overestimation of active layer thickness (ALT) and soil moisture, and large differences in established forests are simulated. We conclude that the coupled version can simulate the complex environment of eastern Siberia by reproducing vegetation patterns, making it an excellent tool to disentangle processes driving boreal forest dynamics.

Thermohydrological Impact of Forest Disturbances on Ecosystem‐Protected Permafrost

“…(2016, 2018) and Kruse, Stuenzi, Boike, et al. (2022). Newly introduced parameters are provided in Table A2.…”

“…To dynamically update the vegetation cover and therefore allow for the simulation of disturbance scenarios we applied the coupled Larix Vegetation Simulator (LAVESI) permafrost energy transfer model (CryoGrid‐Vegetation) described in Kruse, Stuenzi, Boike, et al. (2022). This coupled model can simulate the energy‐ and water exchange processes in permafrost‐larch environments including mortality after different disturbance scenarios and reestablishment of larch taxa.…”

“…We apply a dynamic vegetation-permafrost model (Kruse, Stuenzi, Boike, et al, 2022), based on the one-dimensional permafrost land surface model, CryoGrid (Westermann et al, 2016), and the individual-based and spatially explicit larch forest model LAVESI (Kruse et al, 2016). The permafrost model was adapted for use in boreal forest ecosystems (Stuenzi, Boike, Cable, et al, 2021;Stuenzi, Boike, Gädeke, et al, 2021) by adding a state-of-the-art multilayer vegetation model (CLM-ml v0, originally developed for the Community Land Model (CLM) by Bonan et al (2018).…”

The Permafrost and Organic LayEr module for Forest Models (POLE-FM) 1.0

“…However, permafrost and the legacies that affect its dynamics are rarely considered in forest models. In fact, just a handful of models explicitly simulate permafrost (Foster et al, 2019;Gustafson et al, 2020;Kruse et al, 2022), and those that do often operate at relatively coarse spatial (≥ 25 ha grid cells) and/or temporal (≥ monthly) resolutions (but see Kruse et al, 2022, who describe a permafrost module that runs with a 5 min temporal resolution). This makes it difficult to capture the fine-scale spatial heterogeneity of permafrost distributions and the effects of daily temperature variability on plant water availability during short but critical shoulder seasons.…”

The Permafrost and Organic LayEr module for Forest Models (POLE-FM) 1.0

“…However, permafrost and the legacies that affect its dynamics, are rarely considered in forest models. In fact, just a handful of models explicitly simulate permafrost (Foster et al, 2019;Gustafson et al, 2020;Kruse et al, 2022), and those that do often operate at relatively coarse spatial (≥ 25 ha grid cells) and/or temporal (≥ monthly) resolutions (but see Kruse et al 2022). This makes it difficult to capture the fine-scale spatial heterogeneity of permafrost distributions and the effects of daily temperature variability on plant water availability during short, but critical shoulder seasons.…”