How well can we model wetlands in tropical and boreal regions?
The role of wetlands in the global methane cycle is the subject of much current interest. Wetlands are generally accepted as being the largest, but least well quantified, single source of methane (CH4), with recent emission estimates ranging from 105-278 Tg yr-1. The majority of naturally-produced C...
| Main Authors: | , , , , , , |
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| Format: | Text |
| Language: | English |
| Published: |
2011
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| Subjects: | |
| Online Access: | http://nora.nerc.ac.uk/id/eprint/16257/ https://nora.nerc.ac.uk/id/eprint/16257/2/iLEAPS_Wetlands_Hayman_201109.pdf http://www.ileaps.org/sci_conf_book/pdf/20110415170106_iLEAPS_Abstract_Wetlands_20110415.pdf |
| Summary: | The role of wetlands in the global methane cycle is the subject of much current interest. Wetlands are generally accepted as being the largest, but least well quantified, single source of methane (CH4), with recent emission estimates ranging from 105-278 Tg yr-1. The majority of naturally-produced CH4 comes from bacteria in wetlands when organic material decomposes under water-logged anaerobic conditions. Their productivity is a function of (i) soil temperature (which governs microbial process rates); (ii) water table depth (which sets the depth of the CH4-generating region); and (iii) the carbon content of the decomposable substrate (which is modulated by factors such as precipitation, permafrost dynamics, vegetation cover, and topography). Tropical wetlands contribute ~75% of global wetland CH4 emissions. The largest fluxes are over South America, equatorial Africa and south-east Asia. These regions also have the highest uncertainties in CH4 emission. In the tropics, inundation by surface water is a particularly important mechanism for wetland formation, mainly because natural and human-induced variations in wetland extent lead to variability in water, heat, and CH4 fluxes. Here, wetland formation is driven by seasonal hydrological variability and a key control on the CH4 emissions is the water table level. Quantifying natural variability in wetland CH4 emissions is therefore vital not only if we want to understand the hydrological drivers of natural CH4 emissions, but also to avoid having natural variability mask anthropogenic emissions. Although the emissions of methane from the wetlands and lakes of the boreal region are smaller than those from tropical wetlands, the size and remoteness of the boreal region pose a significant challenge to the quantification of both terrestrial ecosystem processes and their feedbacks to regional and global climate. In recent years, Earth Observation (EO) data have demonstrated the potential to become a major tool for characterizing the main processes and estimating key ... |
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