Trace Greenhouse Gas Fluxes in Upland Forests
Tree stems can act as a conduit for trace greenhouse gases (GHG) produced in the soil. However, the majority of studies describing tree stem fluxes of methane (CH ) and nitrous oxide (N O) have ₄) and nitrous oxide (N₂O) have ₂O) have focused on wetland ecosystems. Tree stem fluxes of GHGs on free-d...
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| Format: | Dissertation |
| Language: | English |
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ProQuest Dissertations & Theses
01-01-2018
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| Online Access: | Get full text |
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| Summary: | Tree stems can act as a conduit for trace greenhouse gases (GHG) produced in the soil. However, the majority of studies describing tree stem fluxes of methane (CH ) and nitrous oxide (N O) have ₄) and nitrous oxide (N₂O) have ₂O) have focused on wetland ecosystems. Tree stem fluxes of GHGs on free-draining soils are understudied, but they are assumed to be a source of CH and a weak source of N O. The work presented in this ₄) and nitrous oxide (N₂O) have ₂O) have thesis aimed to determine how climatic variables, soil abiotic conditions, and tree species influence CH and N O fluxes in forests on free-draining soil. Soil and stem CH and N O fluxes were measured in ₄) and nitrous oxide (N₂O) have ₂O) have lowland tropical rainforest in Panama, Central America and temperate woodland in the UK, using chambers installed on the forest floor or strapped to individual stems of two common tree species. Air samples were collected every two to four weeks during 5 months in 2014 and during November 2015 at the tropical site, and between February 2015 and January 2016 at the temperate site.Tree stem CH fluxes differed significantly between species at both sites and stem N O fluxes ₄) and nitrous oxide (N₂O) have ₂O) have also differed between species at the tropical site. However, there was little variation in soil CH or ₄) and nitrous oxide (N₂O) have N O fluxes. At both sites, tree-mediated CH fluxes declined from positive values (emission) at the ₂O) have ₄) and nitrous oxide (N₂O) have stem base to negative values (uptake) higher up. Stem CH fluxes generally increased significantly ₄) and nitrous oxide (N₂O) have with solar radiation, suggesting a link to photosynthetic activity mediated by tree water transport.Collectively, these results show that trees on free-draining soils could act as net sinks for CH₄) and nitrous oxide (N₂O) have and N O. These findings will improve GHG budgets because tree stem uptake is currently ₂O) have unaccounted for. In particular, if uptake of CH by tree stems on free-draining soils is widespread, ₄) and nitrous oxide (N₂O) have the global terrestrial CH sink could be much larger than currently estimated. |
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| ISBN: | 1658460758 9781658460750 |