The North Central United States is divided into several physical provinces based on geologic and topographic features. UNDERC lies in the Northern Highland Province which is the southernmost extension of the Canadian Shield. This province is characterized primarily by Precambrian bedrock (igneous and metamorphic) which is capped by a thin layer of sedimentary rocks left by the Paleozoic seas. On top of this are glacial deposits left by the Woodfordian and Valderan substages of the Wisconsinan glaciers. The Valderan glaciation (approximately 12,000 years ago) was the last of the Wisconsinan age and modified most of northern Michigan and parts of northeastern and northwestern Wisconsin.
Located in the Highland Lake District, UNDERC lies in an area where the glacial deposits are young and the drainage system is poorly developed. This district serves as the headwaters for many major river systems (i.e. Wisconsin and Menominee), and as much as 40% of the district is either open water or swamp. The surface deposits are indicative of the glacial retreat consisting of either infertile, sandy, pitted glacial outwash or boulder and clay morainic deposits (unsorted, unstriated deposits left at the active edge of the ice). Therefore, the soils are generally unsuitable for agriculture. As a result of their composition, the soils also have a reduced capability for cation exchange leaving them very susceptible to acidification. Such susceptibility aids in the formation of bogs.
Many of the lakes in this region are kettle lakes (formed by buried ice which, when melted, left a depression that intersects with the water table). Other lakes originate from irregular depressions in the ground moraine or from areas scoured out of bedrock as the glaciers passed. Swamps and marshes are often associated with the latter type of lake. In this case, the depression may not have been deep enough to form a lake or is a vestige of a lake that has filled with vegetation and sediments.
Since UNDERC is at 46° N latitude, it can be expected to remain cool during much of the year. Climatological maps classify the region as "humid microthermal" which is no dry season with cold winters and cool, long summers. Average temperatures in January range from -4°F (-20°C) to 14°F (-10°C). The average date of the last killing frost is June 3; therefore, it can still be quite cool early in the summer season. In general, the lakes on the property are clear of ice by the last week of April, but ice can remain as late as May 15.
Average temperatures in July range from 61°F (16°C) to 70°F (21°C), although it may get quite warm in protected, low lying areas. The relative humidity during July averages 60 to 70%. Dominant winds come out of the west.
Annual precipitation ranges between 20" (50 cm) and 40" (100 cm) of snow and rain. The region has more than 1" (2.5 cm) of snow cover for over 120 days in an average year. The first frost of the fall usually occurs around September 21, although frosts can occur during any month of the year. During late October or early November, the lakes freeze over until the following May. Ice may attain thicknesses in excess of 32" (82 cm).
LIMNETIC COMMUNITIES: LAKES AND BOGS
Limnetic communities basically consist of two components: the nekton (free-swimming organisms - i.e., fish) and the plankton (organisms subject to movement by the currents). The plankton are further divided into phytoplankton (photosynthetic organisms), zooplankton, and bacteria and viruses. Most research on plankton at UNDERC has been directed toward the phytoplankton and zooplankton. Using sunlight as energy, phytoplankton fix and store inorganic carbon and are the basis of the food web. Each lake on the UNDERC property has its own particular assemblage of algal species, but most contain these major groups: Cyanophyta (blue-greens), Chlorophyta (greens), Chrysophyta (golden-browns, including the diatoms), Pyrrhophyta (dinoflagellates), and Cryptophyta (cryptomonads).
The primary consumers in these lakes are the herbivorous zooplankton. Many zooplankton species feed preferentially on appropriately sized algae (algal body form can also be important). Smaller zooplankton such as Keratella cochlearis feed on smaller algae. Larger zooplankton such as some cladocerans and copepods (both crustaceans) and larval fish filter a larger range of algal sizes. The food web progresses with the secondary consumers. Carnivorous zooplankton include Mesocyclops and Epischura (both copepods), and Chaoborus (phantom midge) larvae. Planktivorous fish (including the young of most fish species and all age classes of the minnow family Cyprinidae) are also secondary consumers. Piscivores such as the northern pike (Esox lucius), muskellunge (Esox masquinongy), smallmouth bass (Micropterus dolomieui), and largemouth bass (Micropterus salmoides) constitute the tertiary consumers, feeding upon smaller fish and even an occasional frog, snake, or bird!
Other fish species commonly encountered at UNDERC include:
The food web within any ecosystem is very complicated. Different life stages of specific organisms can have very different food preferences. Also, within any group of zooplankton or aquatic insects, species often exploit several food sources which makes characterization of diet type difficult. As a further complication, many zooplankton migrate vertically and horizontally within the water column; Daphnia species are noted for this behavior.
Historically, nutrient load (mainly phosphorus) was considered responsible for the abundance of phytoplankton in a lake. However, recent research (much of which has been conducted at UNDERC) shows that the amount of algae in lakes can also be altered by manipulating fish populations. Whole-lake experiments exploring the relationships between fish populations and the plankton are currently underway in Long, Peter, and Paul lakes.
Most of the Northern Forest in this area is now largely second-growth consisting chiefly of aspen-birch, pine, or swamp-conifer with some red or sugar maple-hemlock (Northern mesic hardwood forest). Heavy logging over most of Michigan's Upper Peninsula between 1880 and 1910 is responsible for the lack of old-growth forest. Major cuttings on UNDERC property occurred between 1900 and 1902 with the last logging operations taking place in 1968. Before 1930, the usual practice was to clear cut. At that time, pine was the target species such that entire stands of hardwoods were cut down for access to one or two pines. On property, a single narrow swath of white pine was not cut; records indicate this stand originally consisted of >80 old-growth pines. Today, about 20 of these pines remain across a 6-acre spread, amidst a stand of mature second-growth hemlock.
A problem that emerged from this practice was fire which commonly swept through the slashings left by the logging operations. During the 1930s, however, changes in economics (species preferences) and approaches to fire protection led to more conservative logging practices. Twenty years later, stands of aspen, birch, and cherry covered most of the area; and 30 years after that, significant quantities of pine and balsam began to appear beneath the established canopy.
Selective logging (mostly aspen in the 1950s and early 1960s) and stumpage removal (of hemlock, hardwoods, etc.) did occur on the property until ca. 1967. Personal correspondence alludes to continued cutting into the 1970s (of aspen), but no large-scale timber harvests have been recorded in the last three decades.
Other more common sources of disturbance to the forest include downbursts and tornadoes. Often locally high winds cause downbursts among the trees in an area creating a gap in the canopy. These windthrows range in size from several miles to several yards in diameter and are very common in this region of the United States. Detailed accounts of such windthrows date back to the 1860s and 1870s and help to illustrate their importance in the ecology of the Northern Forest. Windstorms were reportedly responsible for the loss of nearly half of the remaining old growth pines in ca. 1914 (for information on this pine stand, see Stearn's 1950 article in our Publication section). Furthermore, a tornado in the 1960s knocked down a large stand of timber just south of Moccasin Lake. Fires frequently follow such wind destruction further modifying the environment before new vegetative growth can begin to establish itself.
Differences in species composition between the original forest and that which replaced it, called succession, has been well documented and is quite obvious in areas of disturbance. Aspen and birch are pioneer species that often colonize after windthrows or fires. Usually, a stand of aspen serves as a shelter crop for more shade tolerant species (such as white pine, red or sugar maple, and hemlock) that can grow under a full canopy such as white pine, red or sugar maple and hemlock. Generally, a particular assemblage can be predicted to be the ultimate stand after sufficient time has passed. However, the path of succession is affected by many factors including the frequency of disturbance and seed availability. Therefore, a complete and predictable series is rarely, if ever, attained.
Trees commonly encountered at UNDERC include:
The Highland Lake District supports a large number of wetlands. These areas are important not only because they occupy a large portion of the land area, but also because they satisfy many other functions. Wetlands play an important role in nutrient cycles, have a high water-retaining capacity (storage and regulation of water flow), and can be extremely productive.
There are three main types of wetlands at UNDERC: bogs, shrub carrs, and marshes. Shrub carr is a shrub swamp containing dense thickets of evergreen or deciduous shrubby species. Where shrub carrs are dominated by alders (Alnus incana), as they commonly are at UNDERC, they are important in the nitrogen cycle. Like some legumes (i.e., peas and beans), alders fix nitrogen in their roots and thus replenish an often limiting nutrient in the soil.
Soft-stemmed plants (e.g. cattails, grasses, sedges) are characteristic of marshes. The soils can either flood periodically or constantly be saturated with water. Where there is open standing water, marshes also support a host of submergent and emergent aquatic macrophytes. Marshes often form along the borders of lakes or streams.
Bogs are characterized by acidic conditions and often have a surrounding forest of tamarack and black spruce. The floor is covered by a thick layer of Sphagnum moss. Where there is open water, a floating mat of Sphagnum and ericaceous shrubs extends out onto the lake surface. The tough roots of the shrubs hold the mat together. Bog shrubs include the commercially important cranberry, Labrador tea, leatherleaf, and bog rosemary. UNDERC bogs commonly harbor orchids, insectivorous pitcher plants, and sundews.
Dead plant material (peat) continually accumulates in bogs reaching several feet in thickness and forming the base of the bog. Decomposition is extremely slow because of the lack of oxygen and the antibacterial properties of Sphagnum. Often, bogs develop from kettle lakes or depressions because there is little or no water flow through the lake creating a relatively isolated system and magnifying the effects of acidification and low decomposition rates.
Plants commonly encountered in the bogs and bog lakes at UNDERC include:
Macrophytes, or higher aquatic plants, abound in the lakes and streams of UNDERC and offer considerable material for study. Because aquatic macrophytes are the largest sessile organisms in freshwater ecosystems, they have a great effect on the physical, chemical, and biological environment. They have a major impact on light extinction, temperature, water flow, and substrate quality, as well as effects on the chemical environment. Oxygen, dissolved organic carbon, and dissolved nutrients (nitrogen and phosphorus) all are influenced by the rate of macrophyte growth and decomposition.
Biologically, aquatic macrophytes seem to satisfy many roles. Some macrophytes provide a favorable substrate for epiphytes (attached algae and microbes). The epiphytes are an important food source for many freshwater gastropods (e.g. snails, Lymnaea). Also, epiphytes can significantly alter the effect a macrophyte has on its surrounding environment by influencing the production and dissolved substance exchange of the complex.
In some situations, the macrophytes are grazed directly. The rusty crayfish, Orconectes rusticus, was responsible for significantly reducing the biomass of some macrophyte species in enclosure/exclosure experiments conducted in Trout Lake. By providing a potential food source, aquatic macrophytes can have an effect on the distribution of many freshwater invertebrates. Aquatic macrophytes also provide refuge for many fish species during varied life stages. Nesting fish can also influence the distributions of certain macrophytes. UNDERC harbors more than 40 species of macrophytes in two distinct community types. Lakes with harder water support dense beds of shrubby macrophytes such as Potamogeton species, coontail (Ceratophyllum demersum), and Bidens . Lakes with soft, clear water are vegetated by lawns of short-statured species such as Lobelia dortmanna , Eriocaulon (pipewort), and Eleocharis . Most of the UNDERC lakes contain yellow and/or white water lilies.
Many species of large and small mammals occur with regularity on the property. These include White-tailed Deer (Odocoileus virginianus), American Black Bear (Ursus americanus), River Otter (Lontra canadensis), Beaver (Castor canadensis), Porcupine (Erethizon dorsatum), Raccoon (Procyon lotor), and Coyote (Canis latrans). Over the past few years, grey wolves (Canis lupus) have reappeared on the property. For a full list, click here.
The avian fauna is extremely rich as a result of the varied habitats available. Most striking of these are Bald Eagles (Haliaeetus leucocephalus) and Common Loons (Gavia immer), both of which breed on the property. Also abundant are a variety of birds specifically associated with wetlands. Ducks in the area include the Mallard (Anas platyrhynchos), Wood Duck (Aix sponsa), and Common Merganser (Merganser merganser). Great Blue Herons (Ardea herodias) can commonly be seen wading along lake shores. UNDERC is also along the migratory route of many birds that do not permanently inhabit the area. Migratory birds include the Least Sandpiper (Erolia minutilla) and the Greater Scaup (Aythya marila). For a full list, click here.
Reptiles of the area include: Common Snapping Turtle (Chelydra serpentina), Wood Turtle (Clemmys insculpta), Western Painted Turtle (Chrysemys picta belli), Red-bellied Snake (Storeria occipitomaculata), Eastern Garter Snake (Thamnophis sirtalis), Northern Ring-necked Snake (Diadophis punctatus edwardsi; rare), and Eastern Smooth Green Snake (Opheodrys vernalis). There are no poisonous snakes native to the area. For a full list, click here.
Amphibians found on the property include: Mudpuppy (Necturus maculosus; rare), Central Newt (Notophthalmus viridescens louisianensis; rare ), Blue-spotted Salamander (Ambystoma laterale), Spotted Salamander (Ambystyoma maculatum), Red-backed Salamander (Plethodon cinereus), Four-toed Salamander (Hemidactylium scutatum), American Toad (Bufo americanus), Northern Spring Peeper (Pseudacris crucifer), Eastern Gray Tree Frog (Hyla versicolor), Pickerel Frog (Rana palustris; rare), Mink Frog (Rana septentrionalis), Northern Leopard Frog (Rana pipiens), Green Frog (Rana clamitans), Wood Frog (Rana sylvatica), and Bullfrog (Rana catesbeiana). For a full list, click here.
The insect fauna of UNDERC is rich and varied. Aquatic insects are unusually abundant with diverse populations of mayflies, stoneflies, dragonflies, and caddisflies. A visiting authority on Odonata commented that he had never seen such large assemblages of some of the dragonflies. Systematic survey of the aquatic insects is ongoing. A reference collection of aquatic forms is currently being accumulated. A survey of the mosquito species has been under way for the past 20 years. Thirty-one species have been found to date, most of them members of the Aedes communis or Aedes excrucians groups. Treehole-breeding Aedes , pitcher-plant-breeding Wyeomyia , and aquatic reed-breeding Mansonia all are abundant. There are also locally intense populations of black flies (Simulium), noseeums (Culicoides), deer flies (Chrysops), and horse flies (Tabanus). As would be expected with abundant deer, there is a dense population of ticks, Dermacentor variabilis. Bloodsucking arthropods can make life unpleasant in late May-July unless one uses ample repellent. By late August, the biting arthropods are no longer of consequence.
California-group encephalitis viruses circulate in local deer and small rodents. Tickborne Lyme Arthritis occurs in nearby sites in Vilas County. There are ample opportunities for studying wildlife disease cycles that are maintained by biting flies and arthropod ectoparasites.
Habitats: northern hardwood forests, lakes and wetlands
