The Beauty in the Bog

Peat can be cut or mined from peatlands for use as fuel, for growing plants, insulation, packaging and beauty treatments. But the bare peat left behind doesn’t support much life. Credit: nz_willowherb, Flickr, CC-BY-NC 2.0

A guest post by Dr Claire Wordley from Conservation Evidence.

Soggy, centuries-dead plants may not sound like they should be a global conservation priority. But peatlands – soils where water saturation prevents organic matter from fully decaying – store 500 billion metric tons of carbon worldwide. That’s more per metre than rainforests, and the equivalent of half of the carbon that is currently in the atmosphere. Peatlands also contain a wide variety of animals and plants, some of which only live in these wet habitats. Bitterns and bearded tits, ruffs and phalaropes, even tigers and orangutans, all call peatlands home.

Healthy peatland vegetation is fundamental to capturing carbon, housing biodiversity and regulating water cycles. This week, an online resource collecting the evidence for what works (and what doesn’t) to conserve and restore peatland vegetation has been published. This is the first chapter of the ‘wetland synopsis’, a three year project to gather the global evidence for the effects of interventions to conserve plant communities in all types of wetlands, run by researchers at Tour du Valat in France in collaboration with Conservation Evidence at the University of Cambridge in the UK.

Across the world, peat has been dug up to add to compost in garden centres, dried out to allow the planting of timber or crops, or even mined as a fuel to burn. As the peatlands are exploited, wonderful and fragile ecosystems are lost. The Dutch landscapes of polders and windmills? Built to keep water out of drained peatland. East Anglia’s arable desert? Once wet fenland on peat soils. Oil palm plantations in Indonesia? Planted after the lush peat swamp forests were cut and burned. But this is not the end of the story; people are working hard to conserve peatland vegetation, and even restore it to some places where it has been lost.

A healthy peatland can contain a mix of mosses, shrubs, trees and open water. Boardwalks allow people to explore and enjoy the bog without damaging the plants. Credit: Tania & Artur, Flickr, CC-BY-NC-ND 2.0

The ‘peatland synopsis’ collects together and summarises the evidence for 120 different ‘interventions’, actions that conservationists might take to conserve or restore vegetation on wet peat soils: areas like bogs, fens and peat swamp forests. The authors, led by Nigel Taylor, gathered scientific papers from over 220 journals, plus unpublished reports by NGOs and governments. Experts then scored the evidence for each intervention, to estimate the benefits of that intervention, any harms arising from it, plus the certainty in the evidence. The results are available for free on the Conservation Evidence website, and those related to restoration can also be found on the Restoration Evidence website, a new site devoted to collecting the evidence for the restoration of habitats globally.

So what can be done to stop the draining of the swamps, and to restore those that have been drained? The gathered evidence can show us the best strategies. ‘Rewetting’ peat, for example by blocking drainage ditches, was the intervention with the most evidence by far. It led to the recovery of bog and fen vegetation in many studies. Removing trees (usually plantation forests) along with rewetting, also tended to increase typical high-latitude peatland vegetation such as Sphagnum moss, cottongrass and sedges, although the precise effects depended on the site. Spreading mosses and other plants over bogs and fens often led to the establishment of typical bog and fen species, although again the success rates varied.

There are large areas of peat swamp in the tropics. It is important to monitor the effects of any conservation interventions, and report the results so others can learn what works and what doesn’t. Credit: CIFOR, Flickr, CC-BY-NC-ND 2.0

Some interventions, however, appeared not to work very reliably. Planting ‘nurse plants’ for peatland vegetation didn’t seem to help (in either tropical or boreal studies). Creating mounds or hollows in the peat surface before planting vegetation didn’t affect Sphagnum cover in Canadian studies, although one study in peat swamp in Thailand reported that planting trees into mounds of peat led to thicker stems. Adding root-associated fungi to plants before planting didn’t work for most of the 15 Indonesian species in which it was studied; however, in one study, some fungal treatments did slightly increase the growth and survival of one species.

There are many things we can do to help peatlands, as researchers, conservationists and individuals. Researchers can test more interventions that might be used to conserve and restore peatland plants – for over half the interventions studied, no evidence was found, and very few studies were found from tropical peatlands. These all represent important knowledge gaps. Conservationists can use the available evidence to make the best possible decisions about what to do with their peatland, and, where possible, test the interventions that they are undertaking and publish the results. Individuals can avoid buying compost containing peat (look for peat-free logos) and avoid palm oil, or buy certified sustainable palm oil products instead. And we can all learn to appreciate swamps, bogs and fens; if you live near a peatland nature reserve then visit, and marvel at the beauty in the bog.

Conservation Evidence website.