Once viewed as useless land, people have come to realise the value of wetlands for many reasons. They are ecologically significant in that they are often the home of many unique species of plants and animals, they play important roles in nutrient cycles, and they often act as water filters – water is cleaned as it passes through a wetland to another body of water.
A peat bog is an unusual system because, unlike normal soil where most organic material is close to the surface of the soil, a peat bog contains almost entirely carbon material that has been derived from the remains of plants that used to live in the peat bog and have built up over many thousands of years.
Peat bogs can be very deep, for example, the Kapua peat bog in the Hauraki area of the Waikato is up to 14 metres deep. This peat has been accumulating over about 18,000 years. The plant material that has been accumulated contains carbon that the plants originally processed from the atmosphere. This makes peat bogs enormous stores of atmospheric carbon. If changes occur that affect the hydrology or the plants of these wetlands, we run the risk of releasing the carbon back into the atmosphere.
Dave Campbell is a hydrologist studying the peat bogs in the Waikato. He says they are quite special and different to many wetlands around the world because some unusual vascular plants provide most of the material that accumulates as peat – sphagnum mosses fill this role elsewhere. Also, the Hamilton bogs can get quite dry during the summer months, and the plants and peat have some unusual properties that reduce the damaging effect of drying out.
Dave’s work contributes a valuable perspective on wetlands, especially because traditionally these environments have mostly been researched by ecologists and less by hydrologists.
Visit Dave Campbell’s website to learn more about carbon exchange in peat bogs.