What are peatlands?

Peatlands are areas that have accumulated layers of peat at their surface. Peat is usually comprised of dead plant remains, although it also can be composed of living or dead soil fauna as well. Peat commonly is defined as accumulated matter that is at least 30% organic matter by dry mass.   Peat thickness can vary tremendously even within a single site, although peat depths exceeding 3-4 meters is common in North America.

There are two main types of peatlands: bogs and fens. Bogs are ombrotrophic, which means that they receive all of their nutrient and water inputs from the atmosphere alone. Fens are minerotrophic, and do receive ground and/or surface water inputs that also may contain nutrients. While the main difference between bogs and fens may seem like hydrology, these two types of peatlands also can vary in water chemistry, productivity, and plant communities. Click here for some relevant literature.

What species are found in peatlands?

Fens are usually dominated by herbaceous plants such as sedges, reeds, and grasses, although woody species such as larch also are common in fens.   Rich fens often are dominated by brown mosses, and were originally named rich fens because of their rich biodiversity or large numbers of indicator species.    Poor fens are dominated by species in the genus Sphagnum, or the peat mosses.   Sphagnum mosses create harsh conditions for other plant species by creating acidic conditions as well as by impeding decomposition, which leads to nutrient deficiencies.   Thus, poor fens tend to be low in biodiversity, or are 'poor' in indicator species.

Bogs also are Sphagnum dominated systems, but also commonly have sparse black spruce (Picea mariana) canopies.   Leather leaf (Ledum groendlicum) and blueberries also are commonly found in northern bogs.

The nutrient poor conditions typical of Sphagnum dominated bogs and poor fens favours the presence of carnivorous plants such as sundews and pitcher plants.   These plants trap and digest insects for at least a portion of their nutrient requirements.  

Where are peatlands found?

Peatlands have a wide geographic region but are found mostly at high latitudes where they cover major portions of Alaska, Canada, Russia, and Fennoscandia. Click here for a map of the world's peatlands.

Peatlands and climate change

Over the past several thousand years, northern peatlands have accumulated organic matter as peat.   About half of this organic matter consists of carbon.   Thus today, peatlands represent one of the largest terrestrial carbon stocks, equivalent to about 30% of the world's soil carbon pool.   Much of this large carbon reserve lies at high latitudes that are expected to experience some of the most dramatic climate change.  

Our group broadly is interested in whether peatlands will continue to serve as a net carbon sink or whether climate change will cause them to switch towards a net source of atmospheric carbon.    The APEX (Alaskan Peatland Experiment) is designed to address some aspects of global climate change and what they mean for peatland carbon cycling.