Peatlands and wetlands

Restoring degraded peatlands can return them to a state of net carbon sequestration and enhance their ecosystem resilience, highlighting the importance of peatland protection and restoration in climate mitigation, according to a synthesis of evidence from temperate and high latitude peatlands.

Taking restoration action to reduce the impounding of wetlands in the contiguous USA will enhance the carbon sequestration potential of presently impounded wetlands by 0.91 Tg CO₂e y⁻¹, suggests an assessment of existing impounded wetland sites, potential restoration scenarios and emissions factors.

Mangroves provide ecosystem services but are threatened by anthropogenic activities. This study identifies priority areas that maximise the protection of mangrove biodiversity and ecosystem services. The authors show that biodiversity can be protected whilst maximising ecosystem benefits, with little or no increase in the protected area required.

Blue carbon benefit has not been compared among mangrove reforestation and afforestation pathways at the global scale. This study shows that mangrove reforestation could perform a greater carbon storage potential per hectare than afforestation as its higher nitrogen availability and lower salinity.

Land management scenarios that restore degraded swamp shrubland areas to swamp forest through blocking minor canal systems could substantially reduce peatland fire occurrence and associated greenhouse gas emissions, according to a machine learning and numerical modelling study.

Global in situ observations show greenhouse gas emissions from wetlands are lowest when the water table is near the surface, and therefore rewetting wetlands could substantially reduce future emissions.

During a period of drought, an intact tropical peatland in Indonesia released half the amount of greenhouse gases as was released from a degraded site, according to a direct comparison of eddy covariance measurements at a pair of peatland sites in Sumatra.

Coastal wetlands restored by Nature-based Solutions can trap more sediments than natural ones, and their efficiency is mainly determined by sediment supply, according to a meta-analysis of studies globally.

Rewetting agricultural peatlands first is the best strategy for reducing cumulative nitrous oxide emissions from European peatlands, according to an analysis of soil bulk density as a proxy for peat degradation.

Plant-available phosphorus declines in paddy soils as atmospheric CO₂ increases, according to long-term free air carbon dioxide enrichment experiments of rice plants.

Elevated atmospheric CO₂ reduces soil carbon accumulation and methane emissions from wetlands by changing soil redox potential resulting from increased oxygen fluxes produced by plants, according to a four-year field experiment.

Heterotrophic soil respiration and subsidence are enhanced by water table decline, with a meta-analysis estimating that soil respiration in drained peatlands across the globe release 645 Mt carbon per year.

Enhanced weathering in tropical peatlands may be an ineffective carbon dioxide removal strategy due to pH-induced increases in soil carbon leaching which lead to increased re-emission of carbon, according to model calculations constrained by observations from Sumatra, Indonesia.

A process-based carbon isotope biogeochemistry model substantially reduces uncertainty in regional and global estimates of the stable carbon isotopic composition of methane emissions from wetlands and suggests rising atmospheric concentrations are due to increased microbial emissions.

Microbial reduction and dissolution of reactive iron (III) mobilizes mineral-bound organic carbon, which contributes to carbon dioxide production and promotes methanogenesis and methane emission before complete permafrost thaw, according to an observational study along collapsing palsa hillslopes in Sweden.

Wetlands dominate methane emissions in Amazonia, with the largest emissions in the east but no discernible temporal trend, according to nine years of atmospheric methane observations across Amazonia.

Future changes in non-growing season conditions, particularly irradiance and temperature, will enhance carbon emissions from a northern peatland, according to projections with a data-driven machine learning model.

A dominance of slow-growing microbes reduces carbon loss in peatlands with predominantly woody vegetation and may help with peatland preservation under climate change, according to a comparison of microbial communities from different types of peatlands.

Physical analysis of processes universal to raised peatlands produces an equation that explains their morphology and carbon storage across biomes, from Alaska to New Zealand.

Northern peatland carbon sink plays a vital role in climate regulation. Here, the authors show that wildfire reduced peatland carbon uptake and enhanced emissions from degraded peatlands; climate change impacts accelerated carbon losses where increased burn rate and severity reduced carbon sink.

Atmospheric methane concentrations are increasing and a process-based model now estimates greater methane emissions from wetlands since 2007 than previous studies. Substantial increases in 2020 and 2021 contributed to record-high growth rates in the atmospheric methane burden.

We reconstruct the spatial distribution and timing of wetland loss through conversion to seven human land uses between 1700 and 2020, elucidating the magnitude and land-use drivers of global wetland losses to improve assessments of wetland loss impacts.

Between around 5,000 to 2,000 years ago, a drying climate in the vast peatlands of the Congo Basin triggered peat decomposition and carbon release to the atmosphere, implying that this region may be vulnerable to future climate change.

Changes in land use threaten the stability of carbon in Peru’s peatlands, which store almost as much carbon as the entirety of the above-ground Peruvian carbon stock but in 5% of the land area, according to maps of the extent and depth of peat.

Deforestation and drainage have made Indonesian peatlands susceptible to burning. Here the authors find that Indonesia’s 2015 fires resulted in economic losses totaling US$28 billion, while the area burned and emissions released could have been significantly reduced had restoration been completed.