How effective is restoration at recreating wetlands?

mangroves-in-the-lamu-area-indian-ocean-coast-of-kenya_af60-2200x1476px_946x318_scaled_cropp

Anand Chandrasekhar, Geneva, 24 December 2013

Despite the challenges, hundreds of wetland restoration projects are in progress around the world. This raises the question of how effective these projects are in terms of increasing wetland area and improving wetland functions.

Wetlands are complex ecosystems. They are a combination of land and water habitats which change with the seasons or sometimes everyday. They owe their existence to unique combinations of water and sediment as well as natural vegetation. Unfortunately, the very complexity that defines wetlands makes it extremely difficult to restore them.

It also makes wetland restoration a very expensive process. Restoration costs start from around € 9000 per hectare for mangrove re-plantation and goes all the way up to € 11 million per hectare for a coral reef in the same region (South-East Asia). Money alone is not enough to restore wetlands. It can also take a long time depending on the type of wetland. For example, mudflats can be restored fairly quickly (1 to 10 years) while blanket, raised bogs that are important for carbon storage can take thousands of years to restore.

Despite the challenges, hundreds of wetland restoration projects are in progress around the world. It is estimated that US$ 3.9 billion is spent on wetlands in the U.S every year under the Clean Water Act alone. Not inconsiderable funds are allocated around the world for wetland projects such as planting mangrove trees. This raises the question of how effective these projects are in terms of increasing wetland area and improving wetland functions. Recent studies have cast doubts on the outcomes of ambitious wetland restoration projects. For example, an analysis of three water diversion outcomes of a $1 billion project to restore Louisiana’s wetlands shows disappointing results. More than two decades of satellite imagery showed that total vegetation and marsh area had not increased significantly despite redirecting water and sediments to these regions. In addition, these regions suffered greater damage during Hurricane Katrina than surrounding areas. Even when allowing for longer timescales, wetland restoration projects can fall short of achieving their goals in terms of ecological functions. A recent analysis of 621 restored wetlands shows that restorations cannot match the functions provided by equivalent natural wetlands even after 50 to 100 years.

One probable reason for disappointing results is that restoration activities are often approached like engineering projects. This often results in overlooking biological realities. For example, efforts to restore mangrove swamps mainly involve building nurseries and planting thousands of seedlings on coastal mudflats. In many cases after few years there is not much to show for all the efforts. An analysis of mangrove restoration projects in Guyana revealed that the mudflats were on average 20 inches lower than ideal in failed projects resulting in tree bottoms and roots spending too much time in saltwater which slowly killed them. Another mistake made during restoration is to attempt to recreate a fully functioning wetland that is identical to the original wetland. This is practically impossible given the number of variables involved in defining a wetland. Restoration should not be confused with re-creation.

The TEEB for Water and Wetlands Report acknowledges that in many cases, restoring a site will not lead to the same level of biodiversity of ecosystem service flows because ecosystem degradation has ensured that one or more thresholds of irreversibility has been passed. Instead restoration projects should focus on one or two objectives such as improvement of water quality or fish stocks and optimize management activities to achieve these objectives. Then nature should be allowed to establish itself under local conditions. This is a more realistic and cost-effective approach to wetland restoration in the long-term. Understanding the limitations of wetland restoration and focusing on delivering a few key benefits is always better than over-promising and under-delivering in the quest for the impossible.

About the author

anandAnand Chandrasekhar, is based in Switzerland and has a Masters in Conservation Biology from the University of Kent, UK and a Bachelors in Forestry from the Tamil Nadu Agricultural University, India. His experience extends to a wide range of environment issues including species conservation, environmental law and policy, natural resources governance, climate change and carbon markets. He now specializes in science and environment communications and enjoys developing thought-provoking content and challenging conventional thinking.

Disclaimer:

The views expressed in this blog are purely those of the author and do not necessarily reflect the views of TEEB and should not in any circumstances be regarded as stating an official position of TEEB.

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