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Title: Cryptic Methane Emissions from Upland Forest Ecosystems

Abstract

This exploratory research on Cryptic Methane Emissions from Upland Forest Ecosystems was motivated by evidence that upland ecosystems emit 36% as much methane to the atmosphere as global wetlands, yet we knew almost nothing about this source. The long-term objective was to refine Earth system models by quantifying methane emissions from upland forests, and elucidate the biogeochemical processes that govern upland methane emissions. The immediate objectives of the grant were to: (i) test the emerging paradigm that upland trees unexpectedly transpire methane, (ii) test the basic biogeochemical assumptions of an existing global model of upland methane emissions, and (iii) develop the suite of biogeochemical approaches that will be needed to advance research on upland methane emissions. We instrumented a temperate forest system in order to explore the processes that govern upland methane emissions. We demonstrated that methane is emitted from the stems of dominant tree species in temperate upland forests. Tree emissions occurred throughout the growing season, while soils adjacent to the trees consumed methane simultaneously, challenging the concept that forests are uniform sinks of methane. High frequency measurements revealed diurnal cycling in the rate of methane emissions, pointing to soils as the methane source and transpiration as the mostmore » likely pathway for methane transport. We propose the forests are smaller methane sinks than previously estimated due to stem emissions. Stem emissions may be particularly important in upland tropical forests characterized by high rainfall and transpiration, resolving differences between models and measurements. The methods we used can be effectively implemented in order to determine if the phenomenon is widespread.« less

Authors:
 [1];  [2]
  1. Smithsonian Institution, Washington, DC (United States)
  2. Johns Hopkins Univ., Baltimore, MD (United States); Smithsonian Institution, Washington, DC (United States)
Publication Date:
Research Org.:
Smithsonian Institution, Washington, DC (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1248029
Report Number(s):
DOE-Smithsonian-08165
DOE Contract Number:  
SC0008165
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Methane emissions

Citation Formats

Megonigal, Patrick, and Pitz, Scott. Cryptic Methane Emissions from Upland Forest Ecosystems. United States: N. p., 2016. Web. doi:10.2172/1248029.
Megonigal, Patrick, & Pitz, Scott. Cryptic Methane Emissions from Upland Forest Ecosystems. United States. https://doi.org/10.2172/1248029
Megonigal, Patrick, and Pitz, Scott. 2016. "Cryptic Methane Emissions from Upland Forest Ecosystems". United States. https://doi.org/10.2172/1248029. https://www.osti.gov/servlets/purl/1248029.
@article{osti_1248029,
title = {Cryptic Methane Emissions from Upland Forest Ecosystems},
author = {Megonigal, Patrick and Pitz, Scott},
abstractNote = {This exploratory research on Cryptic Methane Emissions from Upland Forest Ecosystems was motivated by evidence that upland ecosystems emit 36% as much methane to the atmosphere as global wetlands, yet we knew almost nothing about this source. The long-term objective was to refine Earth system models by quantifying methane emissions from upland forests, and elucidate the biogeochemical processes that govern upland methane emissions. The immediate objectives of the grant were to: (i) test the emerging paradigm that upland trees unexpectedly transpire methane, (ii) test the basic biogeochemical assumptions of an existing global model of upland methane emissions, and (iii) develop the suite of biogeochemical approaches that will be needed to advance research on upland methane emissions. We instrumented a temperate forest system in order to explore the processes that govern upland methane emissions. We demonstrated that methane is emitted from the stems of dominant tree species in temperate upland forests. Tree emissions occurred throughout the growing season, while soils adjacent to the trees consumed methane simultaneously, challenging the concept that forests are uniform sinks of methane. High frequency measurements revealed diurnal cycling in the rate of methane emissions, pointing to soils as the methane source and transpiration as the most likely pathway for methane transport. We propose the forests are smaller methane sinks than previously estimated due to stem emissions. Stem emissions may be particularly important in upland tropical forests characterized by high rainfall and transpiration, resolving differences between models and measurements. The methods we used can be effectively implemented in order to determine if the phenomenon is widespread.},
doi = {10.2172/1248029},
url = {https://www.osti.gov/biblio/1248029}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Apr 19 00:00:00 EDT 2016},
month = {Tue Apr 19 00:00:00 EDT 2016}
}