Abstract

Forested wetlands are a globally significant source of atmospheric methane (CH₄), and tree stems potentially contribute a large portion of emissions from these systems. However, tree stem emissions in temperate wooded wetlands, particularly those experiencing disturbance, remain largely unexamined. This study investigated the effects of emerald ash borer invasion on CH₄ fluxes from soils and tree stems in temperate wetlands of Western New York. Methane fluxes were measured from live trees, dead trees, and soils in wetlands with different emerald ash borer impact levels (high/open canopy and low/closed canopy). During eight campaigns carried out across the majority of the growing season (May–October 2024), CH₄ emissions varied spatially and seasonally, with the highest fluxes consistently observed at wetter, closed-canopy sites. Live tree stems emitted significantly more CH₄ than dead stems (~12x), and stem fluxes were positively correlated with soil moisture and air temperature, the same drivers that were also identified for soil fluxes. However, tree stem contributions to net ecosystem CH₄ flux (NEF) were relatively minor (0.1–16.1%) compared to soils. Soil fluxes represented the dominant CH₄ emission pathway with a peak site average flux of 5,813 mg CH₄ m⁻² d⁻¹ observed at a closed canopy site in August. Open-canopy sites were drier and emitted less CH₄ than closed-canopy sites. While tree stems are a non-negligible pathway for CH₄ emissions, the dominant role of soil emissions in these sites suggests that direct effects of tree mortality on CH₄ transport and emissions will not be the primary way in which CH₄ dynamics are altered by emerald ash borer invasion. Rather, cascading effects from widespread tree mortality and subsequent ecosystem shifts that alter key controllers of CH₄ production, particularly soil moisture and herbaceous layer vegetation, will dictate CH₄ flux responses to emerald ash borer invasion.

Library of Congress Subject Headings

Wetland ecology; Emerald ash borer; Methane

Publication Date

4-25-2025

Document Type

Thesis

Student Type

Graduate

Degree Name

Environmental Science (MS)

College

College of Science

Advisor

Carmody McCalley

Advisor/Committee Member

Elizabeth Hane

Advisor/Committee Member

Elle Barnes

Campus

RIT – Main Campus

Plan Codes

ENVS-MS

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