Drought effects on wetland soils

Soils associated with wet or ephemerally wet environments cover an area of 12.1 million km2 globally and provide an estimated $27 trillion in regulatory services (e.g. water flow regulation, water purification, erosion prevention and nutrient cycling). Wet soils play a critical role in ecosystem functioning but are increasingly at risk due to increasing drought frequency and severity. To better understand the impacts of drought on wet soils, Stirling et al. (2020) conducted a literature review to examine changes in soil geochemistry in response to drought and the effects of drought on greenhouse gas (GHG) emissions. 

Stirling et al. found that the primary risk associated with drought is the oxidization of wet soils leading to increased acidity. This increased acidity resulted in metals held within the soils to leach into the water, decreasing water quality. Drought was also found to increase organic matter decomposition, and thus increase the release of GHGs such as CO2. While drier soils tend to result in lower methane (a more potent GHG than CO2) emissions compared to wet soils, drier soils can increase remediation challenges because of the fundamental biogeochemical changes resulting from drought conditions. Learn more here.

The effect of seasonal ground ice and peatlands in the western boreal plains

Peatlands in the Western Boreal Plains are abundant despite annual potential evapotranspiration often exceeding precipitation in any given year. One mechanism that supports the persistence of peatlands on the landscape is seasonal ground ice (SGI). SGI typically forms when ground temperatures reach below zero degrees celsius and differs from permafrost in that it melts annually.  

To better understand the role of SGI during the spring melt, Van Huizen et al. (2019) quantified SGI characteristics and examined microtopographical and hydrological processes during the melt period at a poor fen near Fort McMurray, Alberta. Van Huizen et al. found that SGI promoted increased evapotranspiration but that in a dry spring SGI can reduce evapotranspiration rates and in turn keep peatlands wet. SGI was also found to improve the resiliency of vegetation such as Sphagnum mosses by providing optimal conditions for photosynthesis early in the growing season. SGI contributes to peatlands' role as a source area for runoff and helps to maintain peatland abundance in the western boreal plains. Learn more here. 

Biophysical climate mitigation potential of boreal peatlands

Peatlands account for 15% of the globe's boreal land area, yet they are underrepresented in models designed to predict future regional and global climate. Peatland heat and water vapour exchange are critical for regulating boreal climates. Therefore, understanding how these dynamics differ between peatlands and upland forests is important for modelling boreal climate systems and understanding climate benefits of peatland conservation and restoration.

Helbig et al. (2020) used energy observations between the land and the atmosphere from North America, Europe and Russia to demonstrate the potential of peatlands to reduce summer air temperature and increase humidity. Researchers found that peatlands transfer more water vapour into the atmosphere than forests, while forests transfer more heat into the atmosphere, thus warming the air, compared to peatlands. Helbig et al. highlight the importance of considering peatlands in climate modelling, ecosystem assessments and land management decisions such as peatland restoration for climate mitigation. Learn more here. 
 

In northern peatlands where permafrost is found beneath the organic soils, the expansion of the frost can cause bulging and raise the permafrost area to create a small hill know as a pingo. DYK pingos can be as large as football stadiums and up to 70 meters tall?

Pingo is an Inuvialuit term that translates to "small hill". Pingos have been used by Inuvialuit people as navigation tools and as lookouts for scanning the landscape for caribou, and the seas for whales and seal. Learn more about pingos here.