Integrating Arctic Plant Functional Types in a Land Surface Model Using Above‐ and Belowground Field Observations. (16th April 2021)

• Record Type: Journal Article
• Authors: Sulman, Benjamin N.; Salmon, Verity G.; Iversen, Colleen M.; Breen, Amy L.; Yuan, Fengming; Thornton, Peter E.
• Is Part Of: Journal of advances in modeling earth systems. Volume 13:Number 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-04-16
• Subjects: Arctic -- biomass -- modeling -- plant functional types -- vegetation; Geological modeling -- Periodicals; Climatology -- Periodicals; Geochemical modeling -- Periodicals; 551.5011
• DOI: 10.1029/2020MS002396
• Languages: English
• ISSNs: 1942-2466

Abstract

Abstract: Accurate simulations of high‐latitude ecosystems are critical for confident Earth system model (ESM) projections of carbon cycle feedbacks to global climate change. Land surface model components of ESMs, including the E3SM Land Model (ELM), simulate vegetation growth and ecosystem responses to changing climate and atmospheric CO2 concentrations by grouping heterogeneous vegetation into like sets of plant functional types (PFTs). Many such models represent high‐latitude vegetation using only two PFTs (shrub and grass), thereby missing the diversity of vegetation growth forms and functional traits in the Arctic. Here, we use field observations of biomass and leaf traits across a gradient of plant communities on the Seward Peninsula in northwest Alaska to replace the original ELM configuration for the first time with nine Arctic‐specific PFTs. The newly developed PFTs include: (1) nonvascular mosses and lichens, (2) deciduous and evergreen shrubs of various height classes, including an alder PFT, (3) graminoids, and (4) forbs. Improvements relative to the original model configuration included greater belowground biomass allocation, persistent fine roots and rhizomes of nonwoody plants, and better representation of variability in total plant biomass across sites with varying plant communities and depth to bedrock. Simulations through 2100 using the RCP8.5 climate scenario and constant PFT fractional areas showed alder‐dominated plant communities gaining more biomass and lichen‐dominated communities gaining less biomass compared to default PFTs. Our results highlight how representing the diversity of arctic vegetation and confronting models with measurements from varied plant communities improves the representation of arctic vegetation in terrestrial ecosystem models. Plain Language Summary: Arctic ecosystems are home to specialized plant communities that have adapted to cold winters and short growing seasons. Arctic plant communities include a diverse group of plants with different heights and growth patterns, and these different types of plants are likely to respond differently to a warming climate and rising atmospheric carbon dioxide concentrations. However, the computer models that are used to predict how ecosystems and climate will change in the future include only a small number of arctic plants. We used measurements of plant biomass across different plant communities in the Seward Peninsula of Alaska, USA to add new types of arctic plants to an ecosystem model. We then simulated how ecosystems would respond to a warming climate and rising levels of atmospheric carbon dioxide using both original and updated versions of arctic plants in the model. The new plant types allowed the model to simulate how ecosystems dominated by tall shrubs could gain biomass at much faster rates than ecosystems with thin soils and small plants. Our results show how including the diversity of arctic plants can improve model predictions of vegetation responses to climate change in the Arctic. Key Points: Biomass measurements of arctic plants in the Seward Peninsula were used to develop nine arctic plant functional types in the E3SM Land Model New plant functional types included mosses, lichens, graminoids, and shrubs of different height classes and leaf habits Simulations across a gradient of plant communities showed how variations in plant traits and soil depth drive different biomass patterns