Public Abstract

DE-SC0025216: Effects of Shifting Temperate Conifer Forest Vegetation Regimes on Above- and Belowground Carbon and Nitrogen Cycling

Award Status: Active

Institution: Board of Regents of the University of Wisconsin System, operating as University of Wisconsin-Madison, Madison, WI
UEI: LCLSJAGTNZQ7
DUNS: 161202122

Most Recent Award Date: 09/11/2024
Number of Support Periods: 1
PM: Bayer, Paul

Current Budget Period: 09/01/2024 - 08/31/2025
Current Project Period: 09/01/2024 - 08/31/2027
PI: Whitman, Thea

Supplement Budget Period: N/A

Public Abstract

Effects of Shifting Temperate Conifer Forest Vegetation Regimes on Above- and Belowground Carbon and Nitrogen Cycling Thea Whitman, University of Wisconsin-Madison (Principal Investigator) Ellen Whitman, Northern Forestry Centre, Canadian Forest Service (Co-Investigator) Benjamin Sulman, Oak Ridge National Laboratory (Unfunded Collaborator) The overall goal is to explore how wildfire-induced changes in vegetation affect C and N stocks in plants and soils, using field sampling, laboratory experiments, microbial community characterization, and modeling, and to accomplish the three objectives. Objective 1.Quantify above- and belowground C and N stocks in temperate conifer forests from the U.S.-Canadian border to central Yukon Territory in Canada, that have undergone recovery vs. regeneration failure after wildfire. Objective 2.Measure the impact of post-fire vegetation transitions on soil microbial community composition and function. Objective 3. Assess how changes in the quantity and quality of litter inputs and changes in microbial community composition and function affect soil organic matter cycling following vegetation transitions. In on-going research led by co-PI E. Whitman, a field sampling campaign is being conducted to characterize aboveground vegetation communities of forests across a latitudinal gradient extending from south-central Alberta to the Yukon Territory. This project will expand this effort by collecting soil samples and additional aboveground measurements. In addition, the project will sample forested areas that burned between 30 and 38 years ago as well as unburned sites. Sites will be located at ecotones where areas of forest transition to prairie or tundra. Measurements of living and dead aboveground vegetation, allometric equations, and species-specific C and N concentration measurements will be used to estimate aboveground biomass and C and N pool sizes. Soil samples collected from 0-100 cm depth and partitioned by horizon will be used to estimate soil C and N stocks (Objective 1). In addition, the team will characterize soil microbial community composition and function and assess their differences between samples from forests on a trajectory of vegetation regeneration vs. forests experiencing regeneration failure. To assess the impact of broadscale shifts in vegetation community composition on microbial community function, the team will screen soil microbial communities for evidence of a “home-field advantage”. Using soil and litter from areas of forest experiencing regeneration failure or experiencing recovery, the team will use a full factorial design incubation to assess the degree to which shifting microbial community composition may influence soil C cycling during times of vegetation transitions (Objective 2). In addition to the planned field work, the team will use a ModEx approach with the Carbon, Organisms, Rhizosphere, and Protection in the Soil Environment (CORPSE) model, a soil organic matter cycling model that can represent key mechanisms driving soil organic matter stabilization and turnover. Results from Objectives 1 and 2, such as vegetation community composition, above- and belowground biomass, and litter degradation rates, will be used to parameterize the model. The team will also integrate substrate-specific controls on litter decomposition into the model and allow these variables to differ between the recovering vs. regeneration failure microbial communities, thus allowing for a comparison of the effects of changing litter inputs andchanging microbial communities over time (Objective 3). The project will improve understanding of the impacts of vegetation shifts in boreal forest ecosystems on belowground C cycling via two mechanisms – shifts in litter inputs to soil and changing microbial community composition and ability to degrade available C substrates. Furthermore, this research addresses the research needs of the EESSD strategic plan in biogeochemical cycling by investigating the impact of interactions between changing wildfire regimes and climate change on above- and belowground C and N cycling. And finally, the proposed research integrates observations and models by both building off of ongoing modeling work and by linking observations and models to improve understanding of Earth system components.

Effects of Shifting Temperate Conifer Forest Vegetation Regimes on Above- and Belowground Carbon and Nitrogen Cycling

Thea Whitman, University of Wisconsin-Madison (Principal Investigator)

Ellen Whitman, Northern Forestry Centre, Canadian Forest Service (Co-Investigator)

Benjamin Sulman, Oak Ridge National Laboratory (Unfunded Collaborator)

The overall goal is to explore how wildfire-induced changes in vegetation affect C and N stocks in plants and soils, using field sampling, laboratory experiments, microbial community characterization, and modeling, and to accomplish the three objectives. Objective 1.Quantify above- and belowground C and N stocks in temperate conifer forests from the U.S.-Canadian border to central Yukon Territory in Canada, that have undergone recovery vs. regeneration failure after wildfire. Objective 2.Measure the impact of post-fire vegetation transitions on soil microbial community composition and function. Objective 3. Assess how changes in the quantity and quality of litter inputs and changes in microbial community composition and function affect soil organic matter cycling following vegetation transitions.

In on-going research led by co-PI E. Whitman, a field sampling campaign is being conducted to characterize aboveground vegetation communities of forests across a latitudinal gradient extending from south-central Alberta to the Yukon Territory. This project will expand this effort by collecting soil samples and additional aboveground measurements. In addition, the project will sample forested areas that burned between 30 and 38 years ago as well as unburned sites. Sites will be located at ecotones where areas of forest transition to prairie or tundra. Measurements of living and dead aboveground vegetation, allometric equations, and species-specific C and N concentration measurements will be used to estimate aboveground biomass and C and N pool sizes. Soil samples collected from 0-100 cm depth and partitioned by horizon will be used to estimate soil C and N stocks (Objective 1). In addition, the team will characterize soil microbial community composition and function and assess their differences between samples from forests on a trajectory of vegetation regeneration vs. forests experiencing regeneration failure. To assess the impact of broadscale shifts in vegetation community composition on microbial community function, the team will screen soil microbial communities for evidence of a “home-field advantage”. Using soil and litter from areas of forest experiencing regeneration failure or experiencing recovery, the team will use a full factorial design incubation to assess the degree to which shifting microbial community composition may influence soil C cycling during times of vegetation transitions (Objective 2).

In addition to the planned field work, the team will use a ModEx approach with the Carbon, Organisms, Rhizosphere, and Protection in the Soil Environment (CORPSE) model, a soil organic matter cycling model that can represent key mechanisms driving soil organic matter stabilization and turnover. Results from Objectives 1 and 2, such as vegetation community composition, above- and belowground biomass, and litter degradation rates, will be used to parameterize the model. The team will also integrate substrate-specific controls on litter decomposition into the model and allow these variables to differ between the recovering vs. regeneration failure microbial communities, thus allowing for a comparison of the effects of changing litter inputs andchanging microbial communities over time (Objective 3).

The project will improve understanding of the impacts of vegetation shifts in boreal forest ecosystems on belowground C cycling via two mechanisms – shifts in litter inputs to soil and changing microbial community composition and ability to degrade available C substrates. Furthermore, this research addresses the research needs of the EESSD strategic plan in biogeochemical cycling by investigating the impact of interactions between changing wildfire regimes and climate change on above- and belowground C and N cycling. And finally, the proposed research integrates observations and models by both building off of ongoing modeling work and by linking observations and models to improve understanding of Earth system components.