1
|
Epron D, Mochidome T. Methane concentration in the heartwood of living trees in a cold temperate mountain forest: variation, transport and emission. TREE PHYSIOLOGY 2024; 44:tpae122. [PMID: 39283730 DOI: 10.1093/treephys/tpae122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Accepted: 09/13/2024] [Indexed: 10/18/2024]
Abstract
Forest soils are the largest terrestrial sink of methane (CH4), but CH4 produced in tree trunks by methanogenic archaea and emitted into the atmosphere can significantly offset CH4 oxidation in the soil. However, our mechanistic understanding of CH4 accumulation in tree trunks, in relation to CH4 emission from the trunk surface, is still limited. We characterized temporal variations in the molar fraction of CH4 in the heartwood of trees ([CH4]HW) of four different species in a mountain forest and addressed the relationship between [CH4]HW and emission from the surface of the trunk (${F}_{CH_4}$), in connection with the characteristics of the wood. [CH4]HW measurements were made monthly for 15 months using gas-porous tubes permanently inserted into the trunk. [CH4]HW were above ambient CH4 molar fraction for all trees, lower than 100 p.p.m. for seven trees, higher for the nine other trees and greater than 200,000 p.p.m. (>20%) for two of these nine trees. [CH4]HW varied monthly but were not primarily determined by trunk temperature. Heartwood diffusive resistance for CH4 was variable between trees, not only due to heartwood characteristics but probably also related to source location. ${F}_{CH_4}$were weakly correlated with [CH4]HW measured a few days after. The resulting apparent diffusion coefficient was also variable between trees suggesting variations in the size and location of the CH4 production sites as well as resistance to gas transport within the trunk. Our results highlight the challenges that must be overcome before CH4 emissions can be simulated at the tree level.
Collapse
Affiliation(s)
- Daniel Epron
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Takumi Mochidome
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| |
Collapse
|
2
|
Vestin P. Forests don't just absorb CO 2 - they also take up methane. Nature 2024; 631:744-745. [PMID: 39048686 DOI: 10.1038/d41586-024-02270-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
|
3
|
Ranniku R, Mander Ü, Escuer-Gatius J, Schindler T, Kupper P, Sellin A, Soosaar K. Dry and wet periods determine stem and soil greenhouse gas fluxes in a northern drained peatland forest. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 928:172452. [PMID: 38615757 PMCID: PMC11071052 DOI: 10.1016/j.scitotenv.2024.172452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 04/10/2024] [Accepted: 04/11/2024] [Indexed: 04/16/2024]
Abstract
Greenhouse gas (GHG) fluxes from peatland soils are relatively well studied, whereas tree stem fluxes have received far less attention. Simultaneous year-long measurements of soil and tree stem GHG fluxes in northern peatland forests are scarce, as previous studies have primarily focused on the growing season. We determined the seasonal dynamics of tree stem and soil CH4, N2O and CO2 fluxes in a hemiboreal drained peatland forest. Gas samples for flux calculations were manually collected from chambers at different heights on Downy Birch (Betula pubescens) and Norway Spruce (Picea abies) trees (November 2020-December 2021) and analysed using gas chromatography. Environmental parameters were measured simultaneously with fluxes and xylem sap flow was recorded during the growing season. Birch stems played a greater role in the annual GHG dynamics than spruce stems. Birch stems were net annual CH4, N2O and CO2 sources, while spruce stems constituted a CH4 and CO2 source but a N2O sink. Soil was a net CO2 and N2O source, but a sink of CH4. Temporal dynamics of stem CH4 and N2O fluxes were driven by isolated emissions' peaks that contributed significantly to net annual fluxes. Stem CO2 efflux followed a seasonal trend coinciding with tree growth phenology. Stem CH4 dynamics were significantly affected by the changes between wetter and drier periods, while N2O was more influenced by short-term changes in soil hydrologic conditions. We showed that CH4 emitted from tree stems during the wetter period can offset nearly half of the soil sink capacity. We presented for the first time the relationship between tree stem GHG fluxes and sap flow in a peatland forest. The net CH4 flux was likely an aggregate of soil-derived and stem-produced CH4. A dominating soil source was more evident for stem N2O fluxes.
Collapse
Affiliation(s)
- Reti Ranniku
- Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, 46 Vanemuise, EST-51014 Tartu, Estonia.
| | - Ülo Mander
- Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, 46 Vanemuise, EST-51014 Tartu, Estonia
| | - Jordi Escuer-Gatius
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 5 Fr.R. Kreutzwaldi, EST-51006 Tartu, Estonia
| | - Thomas Schindler
- Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, 46 Vanemuise, EST-51014 Tartu, Estonia
| | - Priit Kupper
- Department of Botany, Institute of Ecology & Earth Sciences, University of Tartu, J. Liivi 2, EST-50409 Tartu, Estonia
| | - Arne Sellin
- Department of Botany, Institute of Ecology & Earth Sciences, University of Tartu, J. Liivi 2, EST-50409 Tartu, Estonia
| | - Kaido Soosaar
- Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, 46 Vanemuise, EST-51014 Tartu, Estonia
| |
Collapse
|
4
|
Jeffrey LC, Johnston SG, Tait DR, Dittmann J, Maher DT. Rapid bark-mediated tree stem methane transport occurs independently of the transpiration stream in Melaleuca quinquenervia. THE NEW PHYTOLOGIST 2024; 242:49-60. [PMID: 37984803 DOI: 10.1111/nph.19404] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 10/27/2023] [Indexed: 11/22/2023]
Abstract
Tree stem methane emissions are important components of lowland forest methane budgets. The potential for species-specific behaviour among co-occurring lowland trees with contrasting bark characteristics has not been investigated. We compare bark-mediated methane transport in two common lowland species of contrasting bark characteristics (Melaleuca quinquenervia featuring spongy/layered bark with longitudinally continuous airspaces and Casuarina glauca featuring hard/dense common bark) through several manipulative experiments. First, the progressive cutting through M. quinquenervia bark layers caused exponential increases in methane fluxes (c. 3 orders of magnitude); however, sapwood-only fluxes were lower, suggesting that upward/axial methane transport occurs between bark layers. Second, concentrated methane pulse-injections into exposed M. quinquenervia bark, revealed rapid axial methane transport rates (1.42 mm s-1 ), which were further supported through laboratory-simulated experiments (1.41 mm s-1 ). Laboratory-simulated radial CH4 diffusion rates (through bark) were c. 20-times slower. Finally, girdling M. quinquenervia stems caused a near-instantaneous decrease in methane flux immediately above the cut. By contrast, girdling C. glauca displayed persistent, though diminished, methane fluxes. Overall, the experiments revealed evidence for rapid 'between-bark' methane transport independent from the transpiration stream in M. quinquenervia, which facilitates diffusive axial transport from the rhizosphere and/or sapwood sources. This contrasts with the slower, radial 'through-bark' diffusive-dominated gas transportation in C. glauca.
Collapse
Affiliation(s)
- Luke C Jeffrey
- School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW, 2480, Australia
| | - Scott G Johnston
- School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW, 2480, Australia
| | - Douglas R Tait
- School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW, 2480, Australia
| | - Johannes Dittmann
- School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW, 2480, Australia
| | - Damien T Maher
- School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW, 2480, Australia
| |
Collapse
|
5
|
Barba J, Brewer PE, Pangala SR, Machacova K. Methane emissions from tree stems - current knowledge and challenges: an introduction to a Virtual Issue. THE NEW PHYTOLOGIST 2024; 241:1377-1380. [PMID: 38267825 DOI: 10.1111/nph.19512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
This article is a Commentary on the Virtual Issue ‘Methane emissions from tree stems – current knowledge and challenges’ that includes the following papers: Barba et al. (2019), Bréchet et al. (2021), Covey & Megonigal (2019), Feng et al. (2022), Flanagan et al. (2021), Jeffrey et al. (2019, 2021, 2023), Kohl et al. (2019), Machacova et al. (2021a,b, 2023), Megonigal et al. (2020), Pangala et al. (2013, 2014), Pitz & Megonigal (2017), Plain et al. (2019), Putkinen et al. (2021), Sjögersten et al. (2020), Takahashi et al. (2022), Tenhovirta et al. (2022), Wang et al. (2016), and Yip et al. (2018). Access the Virtual Issue at www.newphytologist.com/virtualissues.
Collapse
Affiliation(s)
- Josep Barba
- CREAF, E-08193, Bellaterra (Cerdanyola del Vallès), Catalonia, Spain
- Universitat de Girona, E-17003, Girona, Catalonia, Spain
| | - Paul E Brewer
- School of Life Sciences, Arizona State University, Tempe, AZ, 84287, USA
| | - Sunitha R Pangala
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
| | - Katerina Machacova
- Global Change Research Institute of the Czech Academy of Sciences, CZ-60300, Brno, Czech Republic
| |
Collapse
|