Wetlands are lands which are either covered by shallow water or have a water table close to the ground. Wetland has a vegetation cover that is water-loving or tolerates water, see Figure 1. Wetlands could be permanent or seasonal. These water-soaked areas are usually connected to a water body such as a river or a lake. Wetlands are of special importance because:
- They can reduce the damage caused by floods,
- They can be used for recreational activities,
- They can be used for timber collection,
- They play a key role in local ecosystems, and,
- They can inhale carbon dioxide in the air.
In Ontario, there are more than 35 million hectares of wetlands. Nipissing University offers a course called the Ontario Wetland Evaluation System. Climate change is expected to be negative feedback for the wetlands as they dry in a warmer environment. Toronto has lost 85% of its wetlands (Toronto and Region Conservation Authority). As such, the government of Ontario offers grants and incentives to encourage the residents to preserve wetlands (Government of Ontario, Wetland Conservation Strategy 2017-2030). Why does it matter so much for the government and the researchers?
Figure 1: Wetland in Ontario (credit: www.ontariowoodlot.com)
Wetlands are among major players in the carbon cycle. Wetland vegetation cover inhales carbon dioxide from the atmosphere. Along with water and sunlight, plants make their food out of these three. That is called photosynthesis. The difference between a wetland and other green areas (such as forests) that also perform photosynthesis is that a wetland ecosystem has a large capacity to store carbon that is 700 kilograms per hectare per year (3). Wetland plants have long roots and even can incorporate carbon into their leaves. Unlike forests, fallen plants do not quickly release carbon back to the atmosphere (www.eos.org). Northern wetlands are of special interest not only because Canada hosts lots of them, but because freezing cycles decrease the decomposition rate of wetland (www.asknature.org). This means that boreal wetlands can live for centuries and serve as natural weather purifiers (1). That is why more than 450 billion tonnes of carbon are stored in North American wetlands (2). But what happens when a wetland is disturbed/dried, either for a nice cottage or as a result of natural wildfire? Not only the wetland is not there to act as a carbon sink, but the stored carbon will also be released back to the atmosphere (4,5). For example, a fire in Indonesian swamps sent 16 million tonnes of carbon dioxide to the atmosphere per day (www.iucn.org). Therefore, the damage is two-fold. So, a powerful yet simple solution to regulate the climate is just let the wetlands be!
1) P.F. Sirin et al., Assessment of peatlands, biodiversity, and climate change, Published by the global environmental center (Kuala Lampur) and wetland international (Wageningen), 2008.
2) E. Gorham, Northern Peatlands: Role in the Carbon Cycle and Probable Responses to Climatic Warming, Ecological Applications, 1991
3) F. Pearce, Peat bogs hold bulk of Britain’s carbon, New Scientist issue 1952, 1994
4) V. Burkett and J. Kusler, CLIMATE CHANGE: POTENTIAL IMPACTS AND INTERACTIONS IN WETLANDS OF THE UNITED STATES, Journal of American Water Resources Association, 2007
Australian Government, Wetlands Australia, National Wetlands Update, September 2012, Issue 21