PEATMAP is a GIS shapefile dataset shows a distribution of peatlands that covers the entire world. It was produced by combining the most high quality available peatland map from a wide variety of sources that describe peatland distributions at global, regional and national levels. The following sequence of comparisons to discriminate between overlapping data sources were used: (1) Relevance. The most important criterion was that source data are able to identify peatlands faithfully and to distinguish them from other land cover types, especially non-peat forming wetlands. (2) Spatial resolution. In areas where two or more overlapping data sources were indistinguishable in terms of their relevance to peatlands, the dataset with the finest spatial resolution was selected. (3) Age. In any areas where two or more overlapping datasets were indistinguishable based on both their apparent relevance to peatlands and their spatial resolution, the data product that had been most recently updated was selected. Recently updated products commonly contain much older source data, the period over which the latest revision source data were collected as the primary measure of the age of a dataset.

PEATMAP: Refining estimates of global peatland distribution based on a meta-analysis

Wise use of mires and peatlands

Peat landscapes will be in focus at the upcoming ‘Global Landscapes Forum: Peatlands Matter’ event, taking place in Jakarta on 18 May 2017. Find out more here.Wetlands are important providers of ecosystem services and key regulators of climate change. They positively contribute to global warming through their greenhouse gas emissions, and negatively through the accumulation of organic material in histosols, particularly in peatlands. Our understanding of wetlands' services is currently constrained by limited knowledge on their distribution, extent, volume, inter-annual flood variability, and disturbance levels. We present an expert system approach to estimate wetland and peatland areas, depths and volumes, which relies on three biophysical indices related to wetland and peat formation: 1. Long-term water supply exceeding atmospheric water demand; 2. Annually or seasonally water-logged soils; 3. A geomorphological position where water is supplied and retained. Tropical and subtropical wetlands estimates reach 4.7 million km2. In line with current understanding, the American continent is the major contributor (45%) and Brazil, with its Amazonian inter-fluvial region, contains the largest tropical wetland area (800,720 km2). Our model suggests, however, unprecedented extents and volumes of peatland in the tropics (1.7 million km2 and 7,268 (6,076-7,368) km3), which more than three-fold current estimates. Unlike current understanding, our estimates suggest that South America and not Asia contributes the most to tropical peatland area and volume (ca. 44% for both) partly related to some yet unaccounted extended deep deposits but mainly to extended but shallow peat in the Amazon Basin. Brazil leads the peatland area and volume contribution. Asia hosts 38% of both tropical peat area and volume with Indonesia as the main regional contributor and still the holder of the deepest and most extended peat areas in the tropics. Africa hosts more peat than previously reported but climatic and topographic contexts leave it as the least peat forming continent. Our results suggest large biases in our current understanding of the distribution, area, and volumes of tropical peat and their continental contributions.

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An expert system model for mapping tropical wetlands and peatlands reveals South America as the largest contributor

Digital mapping of peatlands – A critical review

Promising native tree species for reforestation of degraded tropical peatlands

Our limited knowledge of the size of the carbon pool and exchange fluxes in forested lowland tropical peatlands represents a major gap in our understanding of the global carbon cycle. Peat deposits in several regions (e.g. the Congo Basin, much of Amazonia) are only just beginning to be mapped and characterised. Here we consider the extent to which methodological improvements and improved coordination between researchers could help to fill this gap. We review the literature on measurement of the key parameters required to calculate carbon pools and fluxes, including peatland area, peat bulk density, carbon concentration, above-ground carbon stocks, litter inputs to the peat, gaseous carbon exchange, and waterborne carbon fluxes. We identify areas where further research and better coordination are particularly needed in order to reduce the uncertainties in estimates of tropical peatland carbon pools and fluxes, thereby facilitating better-informed management of these exceptionally carbon-rich ecosystems.

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Improving estimates of tropical peatland area, carbon storage, and greenhouse gas fluxes

. The Amazon plays a critical role in global atmospheric budgets of methane (CH4) and nitrous oxide (N2O). However, while we have a relatively good understanding of the continental-scale flux of these greenhouse gases (GHGs), one of the key gaps in knowledge is the specific contribution of peatland ecosystems to the regional budgets of these GHGs. Here we report CH4 and N2O fluxes from lowland tropical peatlands in the Pastaza–Maranon foreland basin (PMFB) in Peru, one of the largest peatland complexes in the Amazon basin. The goal of this research was to quantify the range and magnitude of CH4 and N2O fluxes from this region, assess seasonal trends in trace gas exchange, and determine the role of different environmental variables in driving GHG flux. Trace gas fluxes were determined from the most numerically dominant peatland vegetation types in the region: forested vegetation, forested (short pole) vegetation, Mauritia flexuosa-dominated palm swamp, and mixed palm swamp. Data were collected in both wet and dry seasons over the course of four field campaigns from 2012 to 2014. Diffusive CH4 emissions averaged 36.05 ± 3.09 mg CH4–C m−2 day−1 across the entire dataset, with diffusive CH4 flux varying significantly among vegetation types and between seasons. Net ebullition of CH4 averaged 973.3 ± 161.4 mg CH4–C m−2 day−1 and did not vary significantly among vegetation types or between seasons. Diffusive CH4 flux was greatest for mixed palm swamp (52.0 ± 16.0 mg CH4–C m−2 day−1), followed by M. flexuosa palm swamp (36.7 ± 3.9 mg CH4–C m−2 day−1), forested (short pole) vegetation (31.6 ± 6.6 mg CH4–C m−2 day−1), and forested vegetation (29.8 ± 10.0 mg CH4–C m−2 day−1). Diffusive CH4 flux also showed marked seasonality, with divergent seasonal patterns among ecosystems. Forested vegetation and mixed palm swamp showed significantly higher dry season (47.2 ± 5.4 mg CH4–C m−2 day−1 and 85.5 ± 26.4 mg CH4–C m−2 day−1, respectively) compared to wet season emissions (6.8 ± 1.0 mg CH4–C m−2 day−1 and 5.2 ± 2.7 mg CH4–C m−2 day−1, respectively). In contrast, forested (short pole) vegetation and M. flexuosa palm swamp showed the opposite trend, with dry season flux of 9.6 ± 2.6 and 25.5 ± 2.9 mg CH4–C m−2 day−1, respectively, versus wet season flux of 103.4 ± 13.6 and 53.4 ± 9.8 mg CH4–C m−2 day−1, respectively. These divergent seasonal trends may be linked to very high water tables (> 1 m) in forested vegetation and mixed palm swamp during the wet season, which may have constrained CH4 transport across the soil–atmosphere interface. Diffusive N2O flux was very low (0.70 ± 0.34 µg N2O–N m−2 day−1) and did not vary significantly among ecosystems or between seasons. We conclude that peatlands in the PMFB are large and regionally significant sources of atmospheric CH4 that need to be better accounted for in regional emissions inventories. In contrast, N2O flux was negligible, suggesting that this region does not make a significant contribution to regional atmospheric budgets of N2O. The divergent seasonal pattern in CH4 flux among vegetation types challenges our underlying assumptions of the controls on CH4 flux in tropical peatlands and emphasizes the need for more process-based measurements during periods of high water table.

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Seasonal variability in methane and nitrous oxide fluxes from tropical peatlands in the western Amazon basin

The Amazon plays a critical role in global atmospheric budgets of methane (CH4) and nitrous oxide (N2O). However, while we have a relatively good understanding of the continental-scale flux of these greenhouse gases (GHGs), one of the key gaps in knowledge is the specific contribution of peatland ecosystems to the regional budgets of these GHGs. Here we report CH4 and N2O fluxes from lowland tropical peatlands in the Pastaza-Marañón foreland basin (PMFB) in Peru, one of the largest peatland complexes in the Amazon basin. The goal of this research was to quantify the range and magnitude of CH4 and N2O fluxes from this region; assess seasonal trends in trace gas exchange; and determine the role of different environmental variables in driving GHG flux. Trace gas fluxes were determined from the most numerically dominant peatland vegetation types in the region: forested vegetation, forested (short pole) vegetation, Mauritia flexuosa-dominated palm swamp, and mixed palm swamp. Data were collected in both wet and dry seasons over the course of four field campaigns from 2012 to 2014. Diffusive CH4 emissions averaged 204.8± 23.5 mg CH4–C m−2 d−1 across the entire dataset, with diffusive CH4 flux varying significantly among vegetation types and between seasons. Net ebullition of CH4 averaged 4625.2± 752.1 mg CH4–C m−2 d−1, and did not vary significantly among vegetation types or between seasons. Diffusive CH4 flux was greatest for forested vegetation (469.3± 179.4 mg CH4–C m−2 d−1), followed by mixed palm swamp (279.5± 82.0 mg CH4–C m−2 d−1), M. flexuosa palm swamp (171.1± 20.1 mg CH4–Cm d−1), and forested (short pole) vegetation (149.2± 21.9 mg CH4– Cm−2 d−1). Diffusive CH4 flux also showed marked seasonality, with divergent seasonal patterns among ecosystems. Forested vegetation and mixed palm swamp showed significantly higher dry season (751.5± 290.4 and 457.6± 132.9 mg CH4–C m−2 d−1, respectively) compared to wet season emissions (31.9± 4.9 and 24.3± 12.9 mg CH4–C m−2 d−1, respectively). In contrast, forested (short pole) vegetation and M. flexuosa palm swamp showed the opposite trend, with dry season flux of 45.3± 12.3 and 97.2± 10.3 mg CH4–C m−2 d−1, respectively, versus wet season flux of 488.1± 64.4 and 285.1± 39.1 mg CH4–C m−2 d−1, respectively. These divergent seasonal trends may be linked to very high water tables (> 1 m) in forested vegetation and mixed palm swamp during the wet season, which may have constrained CH4 transport across the soil–atmosphere interface. Diffusive N2O flux was low (7.90± 4.93 μg N2O–N m−2 d−1), and did not vary significantly among ecosystems or between seasons. We conclude that peatlands in the PMFB are large and regionally significant sources of atmospheric CH4 that need to be better accounted for in regional emissions inventories. In contrast, N2O flux was negligible, suggesting that this region does not make a significant contribution to regional atmospheric budgets of N2O. The divergent seasonal pattern in CH4 flux among vegetation types challenges our underlying assumptions of the controls on CH4 flux in tropical peatlands, and emphasizes the need for more process-based measurements during high water table periods.

/pdf/corrigendum-to-seasonal-variability-in-methane-and-nitrous-3qdln98w7l.pdf

Corrigendum to “Seasonal variability in methane and nitrous oxide fluxes from tropical peatlands in the western Amazon basin” published in Biogeosciences, 14, 3669–3683, 2017

Wayne A. Murphy

Papers

Improving estimates of tropical peatland area, carbon storage, and greenhouse gas fluxes

Seasonal variability in methane and nitrous oxide fluxes from tropical peatlands in the western Amazon basin

Corrigendum to “Seasonal variability in methane and nitrous oxide fluxes from tropical peatlands in the western Amazon basin” published in Biogeosciences, 14, 3669–3683, 2017

Temporal variability in methane fluxes from tropical peatlands within the Peruvian Amazon