Rewetting of drained forest wetlands: strategies for implementation and adaptation to future climate

Background

Sweden has extensively drained forest wetlands over the last 150 years to improve forest productivity. However, draining has negatively affected biodiversity, carbon sequestration, risks for downstream flooding, and forest growth resilience.

In a future climate, retaining extensive drained forests may

• increase risks of forest fires, droughts and floods;
• further increase CO2 emissions, degradation of biodiversity, water quality and opportunities for humans to experience and understand healthy ecosystems;
• contribute to new or more frequent outbreaks of infectious deceases;
• and escalate the spread and damage of bark beetle and other pests.

There is strong societal interest in reversing these risks by restoring drained wetlands. But is it possible to fully recover the many environmental and societal benefits associated with natural wetlands? And can restoration lead to any yet poorly understood environmental or societal risks?

Aim

Potential risks of wetland restoration have been insufficiently considered and explored. Existing research typically studied different aspects separately. This program studies how wetland restoration affects multiple aspects in the same experimental design, including 20 wetland restorations and 20 drained references wetlands, with varied landscape and design factors. The overall aim of this program is to determine where and how wetlands can be restored to maximize benefits and reduce negative impacts.

Subprojects

We will achieve our aim through a series of specific objectives connected to eight subprojects (SP) including one coordinating subproject (SP1).

The SP:s will evaluate where (landscape type) and how (design features) wetland restoration are most likely to:

• improve the water holding capacity in the wetland and surrounding soils (SP2)
• improve, or at least maintain, water quality in downstream waters, including methylmercury (MeHg), organic carbon (OC), and nutrient concentrations (SP3)
• reduce net GHG emissions (SP4)
• increase biodiversity and reduce vector-borne and zoonotic pathogens (SP5)
• reduce spruce bark beetle and other pest infestations (SP6)
• enhance environmental values for human recreation (SP7)

Furthermore, the program will:

• use data from SP2-SP3 to model the potential of wetland restoration to improve water holding capacity and water quality in a landscape scale and in a future climate (SP8).

The overall project (SP1) will:

• create a planning tool based on an integrated assessment, to guide decisions on where and how to restore wetlands to maximize benefits and reduce negative impact for the environment and society.

Participants outside of SLU

Freddie Lymeus, Uppsala University. Project leader, SP7.
Irena Creed, University of Toronto
Terry Hartig, Uppsala University
Peter Berg, SMHI