Moist and wet forests are particularly valuable for biodiversity and help counteract the effects of climate change. However, many of these forests in Switzerland have been drained over the past few centuries.
Researchers from Eawag, WSL, and ETH, together with experts from the field, outline in a newly published guide the positive effects of moist forests and the measures needed to restore them. Restoring moist forests promotes biodiversity and benefits both people and animals.
Humans have significantly interfered with nature
Over the past few centuries, humans have significantly interfered with nature. As a result, wet forests—including floodplain, swamp, and bog forests—have been systematically drained or cleared to make way for forestry and agriculture. However, these forests provide unique habitats for a wide variety of living organisms. This diversity is to be promoted once again as part of Switzerland’s biodiversity strategy through the conservation, enhancement, and restoration of valuable habitats. Wet forests are at the center of these efforts. “Wet forests and their water bodies are often quickly discovered and adopted as habitats by amphibians, insects, and other species,” explains Karen Bussmann-Charran, a researcher in the Department of Aquatic Ecology at the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and a member of the Biodiversity Synthesis Center, a joint initiative of Eawag, the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), and ETH Zurich.
Restoring these habitats also promotes, for example, sphagnum moss, which can store large amounts of CO2. But many other organisms benefit as well: for instance, about 84% of all species in Switzerland can be found in floodplains; they are therefore particularly valuable for a large part of the country’s biodiversity.
How can forests be restored to their original state?
To provide practitioners with practical guidance for projects aimed at restoring these wet forests, the Biodiversity Synthesis Center formed a working group comprising experts from both research and practice. The group’s goal was to identify open questions on the topic and answer them in the most user-friendly way possible.
Minor structural measures are sufficient
In the resulting guide, the authors describe various possible approaches. Since wet forests are usually found in areas along riverbanks, in bogs, and in former floodplains, simple structural measures can, for example, restore the water balance. Filling in drainage ditches, removing drainage pipes, or restoring streams and rivers to their natural state are just a few of the possibilities. However, project managers can also enlist a natural—and even more cost-effective—helper: the beaver. In waterways colonized by these industrious builders, moist and wet forest habitats develop almost on their own, transforming the surrounding area into a biodiversity hotspot.
Moist forests come in various forms
Wet forests come in various forms—for example, as floodplain or bog forests, or as spring habitats. The new guide addresses possible measures for restoring these different forest types.
However, restoring former moist forests not only promotes biodiversity but also offers numerous benefits for people and animals in the context of advancing climate change. The water table is raised, thereby enhancing the forests’ resilience to drought and aridity. This stores water in the landscape and provides cool refuges for many living creatures. “This includes humans as well,” says Bussmann-Charran. The lower soil temperature and the resulting cooling effect are not limited to the forest area itself but also extend to adjacent residential areas. Water retention also contributes to flood protection.
Taking Concerns Seriously
However, restoring these areas is not without its challenges: “From a methodological standpoint, it can be challenging at times to locate all drainage ditches and render them permanently ineffective—our guide provides instructions and references to resources that can make planning and implementation more efficient,” explains Bussmann-Charran. It also often takes some persuasion to allay forest owners’ concerns, as a wet forest can be less productive and more difficult to manage. However, according to the aquatic ecologist: “Based on the experience of professionals in the field, once the measures are implemented, forest owners are often proud and happy about the resulting beauty and noticeable biodiversity.”
Guide
The guide “Promoting Biodiversity by Restoring Wet and Wetland Forests” is available in German and French. The content ranges from a compilation of arguments for restoring wet forests to methodological questions regarding the restoration of various categories of wet forests (e.g., floodplain forests, bog forests) and natural allies such as beavers, to aspects of the legal framework and project planning. The guide is intended to support experts and forest owners in the design, planning, and implementation of projects to restore moist and wet forests, thereby contributing to the promotion of biodiversity and other positive aspects of such habitats.
