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Home , Fen, Marsh, Paludification

PART IV: Management

BOGS AND

ogs and their close cousins-- are both considered peatlands, fens--are biologically fascinat- what sets them apart from each Bing . Their deep other is the source of their water layers offer a glimpse into the supply. Fens typically are fed by a geologic past--seeds, plant parts, steady source of ground water and even animals may remain whereas are usually enclosed intact in the acidic peat for thou- depressions filled by rain water. sands of years. If a or exists on your property, consider These unusual wetlands are yourself lucky as they are very rare. home to a variety of plants and ani- mals including unique bog lem- In Michigan, bogs and fens mings, pitcher plants, and sun- occurred historically as a result of dews. The familiar song sparrow glaciation, dating from about 8,000 and red-winged blackbird live there to 12,000 years ago when the last along with yellow-bellied flycatch- ice sheets retreated north, ers, and Nashville warblers, which although some bogs and fens are nest only in northern Michigan. pitcher plant only 3,000 to 5,000 years old. The American goldfinch, American retain water from precipitation, and retreat of these glaciers created woodcock, alder and willow fly- moss, which grows climates, and over time, catchers, and golden-winged and abundantly over the layers of peat of spruce and fir, which still chestnut-sided warblers are other found here. Common shrubs dominate in the north. However, birds that use them. Ruffed grouse include leatherleaf, bog laurel, bog bogs and fens began to form in eat the catkins of bog birches, rosemary and Labrador tea. areas that were too wet for most which often grow around the edges Blueberries and are to grow, and that had poorly of bogs and fens, and migrating also common. drained dark soils and cold water. ducks use their open pools. Although both bogs and fens are Because bogs attract insects, Although they occur through- similar types of wetlands as they shrews, mice, frogs, and toads, they also attract mink, , out Michigan, bogs are more herons, and other predators. numerous in the Upper Peninsula Moose also use these areas in the where they are found along the Upper Peninsula. In winter, the margins of and and in white cedar forests that often sur- depressions created by glacial round many bogs yield important activity. Many southern Michigan browse and cover for deer. bogs, however, were converted to muck farms, and in many other Bogs cases landowners felled the trees, Bogs are unique wetlands drained the bogs, and plowed the because their nutrient-poor sys- soil for agriculture. tems support a specific group of plant species. Such plants include Bogs often lie in frost hollows carnivorous species such as pitcher or other cold, wet environments plants, sundews, and bladderworts, where cold air and water are which eat insects and are able to trapped. On clear nights, heavier cold air settles to the ground and - bogs begin as flows down slopes and valleys reeds, sedges, and mosses around often ending in bog lakes or ponds. the edges of lakes formed by Although daytime surface tempera- glaciation. This vegetation slowly tures may reach 90 to 100 degrees expands across the entire lake sur- Farenheit, the root level of plants face, forming a floating mat of growing within a bog are typically peat. This mat slowly consolidates 45 to 55 degrees Farenheit. and is then dominated by sphag- Because of the great insulating num moss and other bog plants. quality of sphagnum moss, these Over time, the peat forms an areas rarely exceed 60 degrees impermeable layer and isolates the Farenheit. bog from the water table. Shrubs and trees then begin to move in. As bogs age, they tend to Thus, this process of natural suc- bulrush become more acidic. As peat accu- cession turns an open-water lake mulates in bogs, it becomes tightly into a forested wetland. This bonates, the water is usually neu- compressed by the weight of mate- process may also reverse itself dur- tral or alkaline. Fens are often rial lying over it, and the oldest part ing cooler and wetter periods and found on hillsides along lakes, turns into fine-textured black muck. become more open. streams, and rivers, which occur in This compressed peat becomes glacial outwash on sandy glacial impermeable, cutting off the bog lakebeds. Others are located in from the water table making it bogs are broad outwash channels. acidic, or mineral poor. Over time, formed by the blanketing of previ- Researchers distinguish among the older peat is colonized by ously dry land by overgrowth of several different kinds of fens: shrubs and then trees such as bog vegetation as it exceeds its fens, northern fens, pat- white pine, tamarack, and black basin boundaries. These bogs can terned fens, and poor fens. spruce. be brought about by climatic change, hydrological change Prairie fens are found in the There are two ways that bogs caused by dams or logging, former oak-savanna prairie region are formed in Michigan: kettle-lake or the natural advancement of a of southern Lower Michigan. They bogs, and paludification bogs. peatland. Once this blanket are very rich in and mag- These processes may take thou- advances and begins to accumu- nesium. Typical plants found in sands of years. In the Great Lakes late, the formerly mineral-rich soil prairie fens are switchgrass, region various estimates for form- is cut off from the water table cre- Indiangrass, big bluestem, sedges, ing a single foot of peat range from ating acidic conditions. This kills rushes, Indian plantain, and prairie 100 to 800 years. many existing trees and allows bog dropseed. The wettest part of a vegetation to dominate. prairie fen, which is usually found near the water source, is called a Fens "sedge flat" because members of Fens are somewhat rare in the sedge family dominate the veg- Michigan. They are peat-covered etation. The "fen " is the grassy wetlands that are springy largest part and is more diverse when walked upon. Fens are fed with many lowland prairie grasses by mineral-rich artesian groundwa- and wildflowers. Slightly elevated ter in the form of springs, rivulets, areas, especially around the upland flats, or saturated peat. The edge, also support tamarack, dog- constant supply of wood, bog birch, and poison sumac. being forced up through accumu- lating peat causes some fens to Northern fens are dominated appear higher than the surrounding by sedges and rushes and are terrain. Because the groundwater is found in areas of northern Michigan sundew rich in calcium and magnesium car- where bedrock is cov- BOGS AND FENS ered with a thin mantle of glacial Management shoe hares may help decrease drift. Marl flats are very common in Considerations the invasion of surrounding these places. Orchids, gentians, Bogs and fens are extremely dogwood, willow, and other and other plants may be present. sensitive to disturbance. Land-own- woody plants because these are Bulrush, spike rush, cinquefoil, ers cannot create bogs or fens on their preferred food in winter. sawgrass, and white cedar usually their property. Bog management surround northern fens. amounts to not disturbing the nat- •Avoid using fertilizers near any wet- ural succession process and hydrol- land. However, be especially careful Patterned fens have a gentle ogy. Modifying the bog to convert near fens as polluted runoff can alter slope of less than one percent per it to a will destroy fen vegetation, gradually increase mile, tend to have both acidic and the original plant community. over natives. alkaline areas, and feature strips of Harvesting the top layers of sphag- Remove invasive species such sedge-peat ridges only a few inch- num for commercial market will as garlic mustard, glossy buck- es high alternating with depres- damage the fragile . thorn, or purple loosestrife, sions. The depressions are wettest Researchers have little information whenever they appear in order with sedge and rush dominating. about the recovery rate of harvest- to avoid future problems. Besides sedges, the ridges may ed bogs but assume recovery is contain sphagnum, bog rosemary, probably very slow or may never •Do not alter water courses. bog birch, shrubby cinquefoil, occur. or water availability leatherleaf, and stunted white is a very important concept in spruce and larch. Patterned fens The following are options to maintaining bogs and fens. For tend to occur on larger flat outwash consider when managing bogs and example, changing water cours- or lake plain areas in the Upper fens: es typically causes the soil to Peninsula. dry out, which can lead to the •Protect the mineral-rich invasion of lowland and upland Poor fens are those peatlands groundwater source of fens and shrub species. Also, with reduced water flow and lower from pollution or drainage or additional water or drought mineral content. Consequently, the other alterations in hydrology. over several years can have a saturated peat is somewhat acidic. major impact on the health and These fens occur throughout the •Avoid diverting or damming condition of these wetlands. northern Lower Peninsula and water flowing out of fens. Draining adjacent uplands Upper Peninsula. Dominated by Mowing for hay and allowing might lead to a higher water sedges and grasses, poor fens lack livestock to graze can also table, which can also affect the the plant diversity of northern and destroy these unique wetlands. site. Also, do not dig a patterned fens. within the site. Because of their •Periodic burning in winter or importance and uniqueness, early spring may help to retard bogs, fens, and their adjacent the invasion of woody species, uplands should be left alone if but because fire can be damaging as well as beneficial, be sure to consult with local fire authorities and a resource professional. Historically, many fens burned along with the surrounding prairie and , which were set by Native Americans or lightning. Fire burned the mulch and top growth of the fen--the specialty plants--with little danger to the peat below because of the steady water supply. •Cottontail rabbits and snow- garlic mustard BOGS AND FENS

you want to maintain the exist- ing bog and fen.

•Create a buffer strip of at least 100 yards around the wetland. This can be done by planting shrubs or grasses, or by not dis- turbing the area. Do not devel- op roads or trails in the bog, fen, or buffer strip.

•If livestock have access to the site, be sure to fence around it because heavy use by cows, horses, or sheep can damage the vegetation, disturb the soil surface layer, and pollute the water with manure.

In summary, bogs and fens are highly unusual, important places. They are important to wildlife seek- ing secure cover where they can feed, nest, rear their young, and escape predators. They also pro- vide areas for many types of unique, threatened, and endan- gered plant and animal species. If you have a bog or fen on your property, enjoy its uniqueness and diverse plant and animal life.

FOR ADDITIONAL CHAPTERS CONTACT: Michigan United Conservation Clubs PO Box 30235 Lansing, MI 48909 517/371-1041

Private Land Partnerships: This partnership was formed between both private and public organizations in order to address private lands wildlife issues. Individuals share resources, information, and expertise. This landowner’s guide has been a combined effort between these groups working towards one goal: Natural Resources Education. We hope this guide provides you with the knowledge and the motivation to make positive changes for our environment.

FOR ADDITIONAL ASSISTANCE: CONTACT YOUR LOCAL CONSERVATION DISTRICT