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Volume 17 - March 2025
Wetlands
As we transition from winter to spring, the snow melts, the frozen lakes thaw and our wetlands come to life. Minnesota has several types of wetlands, each with widely varying characteristics. Some wetlands are dry for much of the year, others are almost always covered by water. Some wetlands have grasses and sedges, or can have shrubs or trees. They might be small, confined basins or might extend for hundreds of miles. Wetlands are among the most productive ecosystems in the world and play an integral role in the ecology of Minnesota.
In this issue of the Reader, we are highlighting some of the latest science around wetlands that examines a variety of topics, from the influence of climate change on mercury transport in boreal peatlands and our understanding of seasonal (ephemeral) ponds in the Great Lakes region, to soil properties and carbon sequestration rates of freshwater mineral soil wetlands, and impacts on calcareous fens. Additionally, the Minnesota Department of Natural Resources recently published the Status and Trends of Wetlands Report that provides an assessment of gains and losses of wetland acres in Minnesota and has contributed to peatland restoration initiatives that you can learn about on the For the Sake of Peat: Peatland Resilience Initiative in Minnesota website.
We hope you enjoy the selection of articles in this month's edition of the Reader!
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The Minnesota Research Reader is a collaboration between the Minnesota Department of Natural Resources and the U.S. Department of Agriculture Forest Service that provides a quick look at emerging research relevant to our work in the state of Minnesota.
This study, published in Water by Forest Service Northern Research Station and University of Minnesota researchers, explores peatlands in Minnesota and other boreal areas as sources of mercury that can be transported in watersheds, released as a gas, and bioaccumulate in food webs. At the Marcell Experimental Forest in northern Minnesota, methylmercury (the kind that can bioaccumulate) is increasing, with increased temperatures in peatland pore water. Landscape-level hydrologic cycles will be key to understanding the connection to downstream aquatic communities.
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A warming climate could result in higher levels of mercury in peatland runoff.
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Peatland restoration may reduce the downstream impacts of mercury.
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A better understanding of the direct effects of restoration on peatland mercury is needed, to maximize the benefits of restoration efforts.
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A collaboration of experts from Michigan Technical University, Forest Service Northern Research Station, Chippewa National Forest, and Superior National Forest, conducted a systematic review to define and quantify attributes of seasonal ponds, summarize mapping and inventory methods, and synthesize impacts on ponds in the western Great Lakes and northeastern United States. Seasonal ponds are challenging to identify, due to their small size, ephemeral hydrology, diverse vegetation, and occurrence across a range of settings. Yet, in order to inform their conservation and management, it is essential to understand seasonal pond distribution and how management impacts them.
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Seasonal ponds are important habitat for invertebrates, amphibians and birds.
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Forested buffers around season ponds appear to minimize the effect of harvesting on these ecosystems.
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Identifying seasonal wetlands remotely is best done with aerial imagery used in conjunction with topographic information and field surveys.
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Wetlands are often recognized as carbon sinks, with wetland restoration serving as a potential carbon mitigation tool. This research from the U.S. Geological Survey investigates how prairie pothole wetlands, including those in Minnesota, can accumulate increasing amounts of soil organic carbon.
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U.S. prairie pothole wetlands contain significant stocks of carbon.
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Wetland restoration in the region can increase carbon sequestration.
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Considering landscape position can help to maximize the carbon sequestration capacity of restored wetlands.
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In this paper, our neighbors at the University of Wisconsin examine the impacts of High Capacity Wells (HCW) on fen floristic quality and composition. HCWs are known to reduce groundwater discharge to fens and impact their floristic quality, but whether HCW impacts are predictive of fen floristic quality across large areas has not been studied. The researchers used Thiem equation-estimated drawdown as an indicator of regional HCW impacts to predict floristic quality, floral richness, and community composition in fens throughout their Wisconsin range.
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HCW influence was associated with a strong decline in floristic quality measures and native-species richness.
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Estimated drawdown was associated with the loss of high coefficient-of-conservatism graminoids and forbs, specialist species, and state-listed rare species.
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The abundance of non-native species and weedy natives increased with increasing HCW influence.
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