<i>Sphagnum</i>-dominated Peatlands in North America Since the Last Glacial Maximum: Their Occurrence and Extent

Halsey, Linda A.; Vitt, Dale H.; Gignac, L. Dennis

doi:10.1639/0007-2745(2000)103[0334:sdpina]2.0.co;2

Cited by 94 publications

(88 citation statements)

References 85 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Peatland data and our model results imply that most of present-day peatlands did not exist or had small areal extents during the LGM. Our simulations do not include other peatlands that may have existed during the LGM or during the course of the Holocene, perhaps at lower latitudes as indicated by paleo records of Sphagnum (Halsey et al, 2000), but then disappeared over time due to changes in climates. By omitting "lost peatlands" we likely overestimate the northern net peatland C sink, as do all estimates based on peat-core data.…”

Section: Discussionmentioning

confidence: 99%

Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century

et al. 2013

View full text Add to dashboard Cite

The development of northern high-latitude peatlands played an important role in the carbon (C) balance of the land biosphere since the Last Glacial Maximum (LGM). At present, carbon storage in northern peatlands is substantial and estimated to be 500 ± 100 Pg C (1 Pg C = 10¹⁵ g C). Here, we develop and apply a peatland module embedded in a dynamic global vegetation and land surface process model (LPX-Bern 1.0). The peatland module features a dynamic nitrogen cycle, a dynamic C transfer between peatland acrotelm (upper oxic layer) and catotelm (deep anoxic layer), hydrology- and temperature-dependent respiration rates, and peatland specific plant functional types. Nitrogen limitation down-regulates average modern net primary productivity over peatlands by about half. Decadal acrotelm-to-catotelm C fluxes vary between −20 and +50 g C m⁻² yr⁻¹ over the Holocene. Key model parameters are calibrated with reconstructed peat accumulation rates from peat-core data. The model reproduces the major features of the peat core data and of the observation-based modern circumpolar soil carbon distribution. Results from a set of simulations for possible evolutions of northern peat development and areal extent show that soil C stocks in modern peatlands increased by 365–550 Pg C since the LGM, of which 175–272 Pg C accumulated between 11 and 5 kyr BP. Furthermore, our simulations suggest a persistent C sequestration rate of 35–50 Pg C per 1000 yr in present-day peatlands under current climate conditions, and that this C sink could either sustain or turn towards a source by 2100 AD depending on climate trajectories as projected for different representative greenhouse gas concentration pathways

show abstract

Section: Discussionmentioning

confidence: 99%

Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Sphagnum spores and peat basal dates both indicate southwards expansions of peatlands into the American Midwest and the east coast of the USA during the deglaciation between 16 and 12 kyr (Halsey et al, 2000;MacDonald et al, 2006). In Europe there is less direct pollen-or core-based evidence during the deglaciation, but van Huissteden (2004) presents some evidence for the expansion of peat layers in northern Europe during MIS 3, also a time period of abrupt shifts in atmospheric CH 4 .…”

Section: Peatland Methane Emission Modelmentioning

confidence: 99%

“…The second involves introducing new peat grid cells in North America and Europe. Over North America, 0.35 × 10 6 km 2 (equivalent to 35 % of the modern distribution for North America) of peatland was prescribed in the area south-west and east the Great Lakes consistent with the areal estimate of Halsey et al (2000) (their Fig. 8), whilst a similar area of peatland was added in northern Europe for comparison.…”

Section: Peatland Methane Emission Modelmentioning

confidence: 99%

Limited response of peatland CH<sub>4</sub> emissions to abrupt Atlantic Ocean circulation changes in glacial climates

Hopcroft

Valdes

Wania³

et al. 2014

Clim. Past

View full text Add to dashboard Cite

Abstract. Ice-core records show that abrupt DansgaardOeschger (D-O) climatic warming events of the last glacial period were accompanied by large increases in the atmospheric CH 4 concentration (up to 200 ppbv). These abrupt changes are generally regarded as arising from the effects of changes in the Atlantic Ocean meridional overturning circulation and the resultant climatic impact on natural CH 4 sources, in particular wetlands. We use two different ecosystem models of wetland CH 4 emissions to simulate northern CH 4 sources forced with coupled general circulation model simulations of five different time periods during the last glacial to investigate the potential influence of abrupt ocean circulation changes on atmospheric CH 4 levels during D-O events. The simulated warming over Greenland of 7-9 • C in the different time periods is at the lower end of the range of 11-15 • C derived from ice cores, but is associated with strong impacts on the hydrological cycle, especially over the North Atlantic and Europe during winter. We find that although the sensitivity of CH 4 emissions to the imposed climate varies significantly between the two ecosystem emissions models, the model simulations do not reproduce sufficient emission changes to satisfy ice-core observations of CH 4 increases during abrupt events. The inclusion of permafrost physics and peatland carbon cycling in one model (LPJ-WHyMe) increases the climatic sensitivity of CH 4 emissions relative to the Sheffield Dynamic Global Vegetation Model (SDGVM) model, which does not incorporate these processes. For equilibrium conditions this additional sensitivity is mostly due to differences in carbon cycle processes, whilst the increased sensitivity to the imposed abrupt warmings is also partly due to the effects of freezing on soil thermodynamics. These results suggest that alternative scenarios of climatic change could be required to explain the abrupt glacial CH 4 variations, perhaps with a more dominant role for tropical wetland CH 4 sources.

show abstract

“…How does the peatland C sequestration history from the NCB approach compare with other studies? In their analysis of soil chronosequence data, Harden et al (1992) indicated that peak peatland expansion occurred 8000-4000 yr ago in glaciated North America. Based on global land ecosystem reconstructions, Adams and Faure (1998) provided an estimate of carbon storage on land since the last glacial maximum.…”

Section: Peatland Changes Over Timementioning

confidence: 99%

Northern peatland carbon stocks and dynamics: a review

2012

Biogeosciences

602

418

View full text Add to dashboard Cite

Abstract. Peatlands contain a large belowground carbon (C) stock in the biosphere, and their dynamics have important implications for the global carbon cycle. However, there are still large uncertainties in C stock estimates and poor understanding of C dynamics across timescales. Here I review different approaches and associated uncertainties of C stock estimates in the literature, and on the basis of the literature review my best estimate of C stocks and uncertainty is 500±100 (approximate range) gigatons of C (Gt C) in northern peatlands. The greatest source of uncertainty for all the approaches is the lack or insufficient representation of data, including depth, bulk density and carbon accumulation data, especially from the world's large peatlands. Several ways to improve estimates of peat carbon stocks are also discussed in this paper, including the estimates of C stocks by regions and further utilizations of widely available basal peat ages.Changes in peatland carbon stocks over time, estimated using Sphagnum (peat moss) spore data and down-core peat accumulation records, show different patterns during the Holocene, and I argue that spore-based approach underestimates the abundance of peatlands in their early histories. Considering long-term peat decomposition using peat accumulation data allows estimates of net carbon sequestration rates by peatlands, or net (ecosystem) carbon balance (NECB), which indicates more than half of peat carbon (> 270 Gt C) was sequestrated before 7000 yr ago during the Holocene. Contemporary carbon flux studies at 5 peatland sites show much larger NECB during the last decade (32 ± 7.8 (S.E.) g C m −2 yr −1 ) than during the last 7000 yr (∼ 11 g C m −2 yr −1 ), as modeled from peat records across northern peatlands. This discrepancy highlights the urgent need for carbon accumulation data and process understanding, especially at decadal and centennial timescales, that would bridge current knowledge gaps and facilitate comparisons of NECB across all timescales.

show abstract

Sphagnum-dominated Peatlands in North America Since the Last Glacial Maximum: Their Occurrence and Extent

Cited by 94 publications

References 85 publications

Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century

Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century

Limited response of peatland CH<sub>4</sub> emissions to abrupt Atlantic Ocean circulation changes in glacial climates

Northern peatland carbon stocks and dynamics: a review

Contact Info

Product

Resources

About

Sphagnum-dominated Peatlands in North America Since the Last Glacial Maximum: Their Occurrence and Extent

Cited by 94 publications

References 85 publications

Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century

Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century

Limited response of peatland CH&lt;sub&gt;4&lt;/sub&gt; emissions to abrupt Atlantic Ocean circulation changes in glacial climates

Northern peatland carbon stocks and dynamics: a review

Contact Info

Product

Resources

About

Limited response of peatland CH<sub>4</sub> emissions to abrupt Atlantic Ocean circulation changes in glacial climates