Northern Mesic Forest (Global Rank G4; State Rank S4)

!( Overview: Distribution, Abundance, !( !( !( Environmental Setting, Ecological Processes !( !( !( !( !( Northern Mesic Forest was historically Wisconsin’s most !( !( !( !(!( !( !(!(!( abundant natural community by far, providing the vegetative !( !( !(!( !( !( !( !( !( !( !( !(!( !(!( !( !( !( !( !(!( !( !( !(!( !( !( context within which many of the state’s lakes, rivers, streams !( !(!( !(!(!( !(!(!(!( !(!( !( !( !(!( !( !( !( !( !( !( !(!( !(!( !( !( !( !( !(!(!(!( !(!(!(!( !(!(!( !( !(!(!( !( !(!(!( !( !(!( !( !(!( and less extensive natural communities were embedded. Vast !(!( !(!(!(!( !( !(!( !(!( !( !( !( !(!( !(!(!( !( !(!(!(!( !( !( !( !(!(!(!( !( !( areas of Wisconsin north of the Tension Zone, estimated at !( !( !( !( !(!(!( !( !( !( !(!( !( !( !( !( !( !( !( !(!( !(!( !( !(!( !( !( roughly 11,750,000 acres by Curtis (1959) and Finley (1976), !( !( !( !( !( !(!( !( !( !( !( !( !(!(!( !( !( !( !( !( !(!( !( !( !(!(!( !(!( !( !(!( !( !( !( !(!(!( !(!( !( !( !( !( or about 33% of the land area of the state (almost 63% of !( !(!( !( !( !(!( !(!(!(!( !( !( !(!( !( !(!( !( !(!(!( !( !( !( !( !(!( !(!( !( !( !( !( !( !( !(!( !( !(!( !( !( !( !(!( northern Wisconsin), were covered by mesic forests com- !( !(!( !( !(!(!(!(!(!( !( !( !( !( !( !( !( !( !( !(!( !( !( !(!( !( !(!( !( !( !(!( !(!( !(!(!( !( !( !(!( !(!( !(!(!(!(!(!( !( posed of eastern hemlock, sugar maple, yellow birch, and !( !( !( !(!( !( !( !( !( !(!( !( !( !( !( !( !(!( American basswood. Between 50% and 68% of this forest !( !( !( !( !(!( !( !( was thought to be in old-growth condition (WDNR 2006). !( !( !( Currently only a minute fraction—well under 1%—of the !( !( millions of acres of Northern Mesic Forest that remain are in !( !( !(!( !( an old-growth developmental stage. !(

Northern Mesic Forest also occurred as outliers, in a nar- !( row strip along Lake Michigan from Marinette south almost to Milwaukee County, and at scattered locations in south- western Wisconsin’s unglaciated Driftless Area well south of the Tension Zone. Away from the climatic influence of Lake Michigan, sites supporting Northern Mesic Forest in southern Wisconsin are often on slopes with cool, moist, north- Locations of Northern Mesic Forest in Wisconsin. This natural community is broadly defined and highly variable. Some subtypes or ern or eastern exposures, often undercut by a stream and variants certainly merit recognition where adequate protection of sometimes receiving cold air drainage. The climatic, geologic, associated biodiversity values is a goal. The deeper hues shading the topographic, and edaphic attributes of the Driftless Area offer ecological landscape polygons indicate geographic areas of greatest these conditions, which are rare in other parts of southern abundance. An absence of color indicates that the community has and central Wisconsin. not (yet) been documented in that ecological landscape. The dots From a continental perspective, similar forests occurred to indicate locations where a significant occurrence of this community the east of Wisconsin in northern Lower Michigan, through- is present, has been documented, and the data incorporated into the Natural Heritage Inventory database. out much of Michigan’s Upper Peninsula, in parts of southern Ontario east of Lake Huron and north of Lake Erie, and east all the way to New England. Mesic forests also occurred in hardwoods.” Though this can be a convenient and useful split northeastern Minnesota, but eastern hemlock was very scarce for some purposes, it can also be quite artificial, or even con- and local there, and American beech was absent. fusing or misleading, as it ignores the impacts of the Cutover “Northern Mesic Forest” is a conceptually broad term that in reducing and even eliminating eastern hemlock (and other encompasses a diverse array of associations and variants, conifers) from large portions of northern Wisconsin’s mesic some with distinctive and recurring canopy and understory forests and may obscure important aspects of stand history, attributes. Stand composition varies owing to geographic loca- previous condition, and associated species or current manage- tion, landform, nutrient status, soil texture, humus type, and ment options and needs. disturbance history. Though the term Northern Mesic Forest Many of today’s northern hardwoods stands historically retains some value as a unifying concept for vegetation across contained a significant component of eastern hemlock, indi- large areas and multiple jurisdictional boundaries in north- cating that current composition is largely the result of fairly eastern North America, it has long been recognized that it recent past human disturbance rather than natural processes. comprises a varied group of cover types, habitat types (Kotar Research has shown that in some of the old-growth northern et al. 2002), assemblages, geographic variants, and plant asso- mesic forests of the Great Lakes states, dominance of the same ciations (Faber-Langendoen 2001). These in turn may offer forest patches was maintained by either eastern hemlock or quite different conservation and management opportunities. sugar maple for centuries, and perhaps even for millennia Sometimes stands with a significant coniferous component (Davis et al. 1995). (especially eastern hemlock) are referred to as “hemlock- Northern Mesic Forest occurs on a variety of glacial land- hardwoods.” Stands composed entirely or mostly of hard- forms, including ground and end moraines, outwash, drum- woods (especially sugar maple) are referred to as “northern lins, eskers, ice-walled lakeplains, mesic but well-drained alluvial terraces, and on the east side of the Door Peninsula wind leave characteristic and important structural features along Lake Michigan, even on stabilized sand dunes. Impor- such as standing snags, pit-and-mound topography, and large tant soils include silt loams, loams, sandy loams, and less coarse woody debris. These provide key habitat features that commonly, sands. Of the 66 stands of Northern Mesic Forest are used by a great number of forest plants and animals, includ- examined by Curtis (1959), the average pH was somewhat ing seedlings of some of the very trees felled by wind storms. acid, at 5.6. In some areas, clays and wind-blown silts (e.g., Other important natural disturbances affecting North- on silt-capped drumlins) were important, affecting drain- ern Mesic Forest include drought, ice storms, and fire. Fires age, nutrient availability, composition, and susceptibility to occurred due to human activities and lightning strikes but windthrow. Sites supporting mesic forest communities are well also where landscapes dominated by mesic forests were bor- drained and seldom if ever subject to severe droughts or pro- dered by fire-prone pine- or oak-dominated ecosystems. In longed saturation or inundation. Internal stand conditions are this situation, low intensity ground fires burned into and characterized by high humidity and dense shade. Soil texture sometimes through the mesic forests (examples of this can varies from coarse to medium on end and ground moraines, still be seen in a few ecological landscapes, such as the North- with fine-textured soils prevalent in or on the margins of gla- ern Highland, where the periodic ground fires that main- cial lakeplains and on some drumlins. In some areas, level to tained the eastern white pine-red pine forests there burned gently rolling ground moraine landforms also have layers of into the adjoining, more fire-resistant forests of eastern hem- windblown silt. Distinctive and ecologically important vari- lock, yellow birch, sugar maple, and American basswood that ants of Northern Mesic Forest may be associated with land- occurred on the more mesic sites). form, soil type, disturbance history, and geographic location. Virtually all of the Northern Mesic Forest in the Great The most common natural disturbance was windthrow, Lakes states was severely cut and subsequently burned during most often at small scales involving individual trees or small the latter half of the 19th century and first few decades of the patches of trees. Stand-replacing catastrophic windthrow at 20th century. In Wisconsin there are no reserves protecting larger scales was associated with severe storms such as down- substantial acreages of old-growth or old Northern Mesic bursts or tornados, which occurred infrequently at periods Forest (WDNR 2006), though in the parts of the Menomi- of several centuries or more (Canham and Loucks 1984). nee Indian Reservation in northeastern Wisconsin, which Medium-scale wind disturbances were also recorded at some escaped the direct destruction of the Cutover and subsequent locales, and these resulted in several distinct age cohorts of slash fires, the Menominee’s forests (managed since the mid- trees within a given stand and also ensured that conditions 1850s) have retained important structural and compositional occasionally occurred that would allow for the reproduction characteristics that have been greatly reduced or disappeared and growth of mid-tolerant tree species (Frelich and Lorimer elsewhere, such as stands of dominant conifers, large living 1991). Large trees snapped off, knocked over, or uprooted by trees, large standing snags, abundant coarse woody debris, and a multi-layered canopy. A key factor is that white-tailed deer populations have been relatively low, allowing important browse-sensitive species such as eastern hemlock, yellow birch, northern white-cedar, and others to reproduce and maintain their populations. Elsewhere in the state, all persisting old-growth remnants are small, many are isolated, and most have been seriously affected by the impacts of high white-tailed deer populations, exotic earthworms, and invasive plants. Community Description: Composition and Structure Old-growth and old stands were dominated by various com- binations of eastern hemlock (Tsuga canadensis), sugar maple (Acer saccharum), and yellow birch (Betula alleghaniensis). The most basic separation differentiates hemlock-hardwoods, Old-growth hemlock-hardwood forests such as this stand in north- in which eastern hemlock is the dominant or a co-dominant ern Vilas County were historically abundant across much of north- tree, from northern hardwoods, in which the canopy is com- ern Wisconsin but are now very rare. They offer unique attributes in posed almost entirely of broad-leaved deciduous trees, espe- terms of structure, composition, and function. Canopy dominants are eastern hemlock, yellow birch, and sugar maple, and this stand cially sugar maple. has retained a few supercanopy eastern white pines. The wire-leaved Canopy composition varies from heavy dominance by sedge-dominated peatland in the foreground would be classified by eastern hemlock to pure hardwoods. In Wisconsin the com- many wetland ecologists as a “poor fen.” Northern Highland Ecologi- munity is most diverse and complex to the north and east, cal Landscape. Photo by Eric Epstein, Wisconsin DNR. with several important species, including canopy dominants such as American beech (Fagus grandifolia) and eastern ginseng (Panax trifolius), hairy Solomon’s-seal (Polygonatum hemlock, dropping out farther west. American beech, for pubescens), twisted-stalk (Streptopus lanceolatus), American example, is limited in distribution to eastern Wisconsin and starflower Trientalis( borealis), and large-flowered trillium is most common in the counties bordering Lake Michigan. (Trillium grandiflorum). Eastern hemlock becomes increasingly rare west of Ashland On acid loams with low nutrient content and mor humus, County and the Apostle Islands. Closer to the Minnesota especially under a dense canopy of eastern hemlock (and border, hemlock occurs sporadically and at only a few loca- sometimes under American beech), the ground layer may tions, eventually becoming rare and no longer functioning be sparse, species-poor, and limited to scattered patches of as a forest dominant. Some of the groundlayer species show wood ferns, club-mosses, Canada mayflower, and moun- similar distributions. In part this is due to changing climatic tain wood-sorrel (Oxalis montana). Stands of heavily cut or conditions, which become drier to the west and favor a group burned hardwoods sometimes feature dense growths of the of boreal species to the north. sod-forming Pennsylvania sedge (Carex pensylvanica), which The dominant trees in Northern Mesic Forest include outcompetes or excludes some of the other native herbs. sugar maple, eastern hemlock, yellow birch, and American Nutrient-rich sites dominated by hardwoods and pos- basswood (Tilia americana). Close to Lake Michigan in east- sessing mull humus are capable of supporting a diverse and ern Wisconsin, American beech reaches its westernmost showy herbaceous flora. Early in the growing season, the range extremities. Though its distribution is quite limited in understory may be composed of a nearly continuous carpet our state, American beech was historically an important and of spring ephemerals and other wildflowers. Plants strongly sometimes dominant canopy species. Eastern white pine (Pinus strobus) was widely distributed across the north, though in the mesic forests, it occurred at very low densities of one or a few trees per acre. On mesic sites, eastern white pine, once established, was capable of achieving great stature and longevity. Among the other canopy associates were white ash (Fraxi- nus americana), American elm (Ulmus americana), red maple (Acer rubrum), northern red oak (Quercus rubra), bitternut- hickory (Carya cordiformis), and butternut (Juglans cinerea). Ironwood (Ostrya virginiana) is sometimes an important subcanopy tree. The shrub layer is seldom well developed in this community under the heavy shade and high canopy closure created by the dominant trees: sugar maple, American basswood, American beech, and especially, eastern hemlock. Shrubs commonly associated with Northern Mesic Forest include beaked hazelnut (Corylus cornuta), American fly honeysuckle (Lonicera canadensis), eastern leatherwood (Dirca palustris), and red-berried elder (Sambucus racemosa). Historically, Canadian yew (Taxus canadensis) was a dominant mesic forest shrub in parts of northern Wisconsin. The effects of heavy logging, post-logging fires, and heavy browse pressure from white-tailed deer (Odocoileus virginiana) have greatly reduced Canadian yew across northern Wisconsin, and it is now rare in or absent from many areas where it was formerly common. Some of the more widespread, characteristic, and repre- sentative groundlayer species are white baneberry (Actaea pachypoda), wood anemone (Anemone quinquefolia), wild sarsaparilla (Aralia nudicaulis), small enchanter’s-nightshade (Circaea alpina), blue-bead lily (Clintonia borealis), spinu- lose wood fern (Dryopteris carthusiana), intermediate wood Complex structure characterizes this old-growth forest remnant of yellow birch, eastern hemlock, northern white-cedar, and balsam fir fern (D. intermedia), fragrant bedstraw (Galium triflorum), over a dense shrub layer of mountain maple and Canada yew. Site common oak fern (Gymnocarpium dryopteris), shining conditions vary from mesic to wet-mesic. This stand was formerly part club-moss (Huperzia lucidula), stiff club-moss (Lycopodium of a lighthouse reservation. Devils Island, Apostle Islands National annotinum), northern tree club-moss (L. dendroideum), Lakeshore, Ashland County, Superior Coastal Plain Ecological Land- Canada mayflower (Maianthememum canadense), dwarf scape. Photo by Eric Epstein, Wisconsin DNR. associated with mesic forest on moist sites with rich soils southern parts of the state, see Chapter 12 (including Table include maidenhair fern (Adiantum pedatum), wild leek 10) in The Vegetation of Wisconsin (Curtis 1959). The dramatic (Allium tricoccum), sharp-lobed hepatica (Anemone acuti- variability exhibited in the herb layer of Northern Mesic Forest loba), broad-leaved toothwort (Cardamine diphylla), blue is an important consideration for managers and conservation- cohosh (Caulophyllum thalictroides), Carolina spring-beauty ists and may be strongly associated with landscape position, (Claytonia caroliniana), squirrel-corn (Dicentra canadensis), moisture class, soil chemistry and texture, disturbance history, false rue anemone (Enemion biternatum), yellow trout-lily and stand origin. (Erythronium americanum), Canadian white violet (Viola After virtually all of Wisconsin’s old-growth forests were canadensis), and several broad-leaved sedges, including white cut during the last half of the 19th century and the early part bear sedge (Carex albursina), plantain-leaved sedge (C. plan- of the 20th century, severe slash fires burned across much of taginea), and on the Door Peninsula of northeastern Wiscon- northern Wisconsin. The burned sites were often colonized sin, broad-leaved sedge (C. platyphylla). Most, though not all by pioneering species, especially quaking aspen (Populus of these stands, are hardwood dominated. tremuloides), white birch (Betula papyrifera), and pin cherry For a discussion of the basic humus types and correlations (Prunus pensylvanica). Today quaking aspen is regenerated with understory composition, the northern and southern via clearcutting and has remained an abundant, sometimes members of the ephemeral pairs, and a summary of understory dominant, forest cover type across much of northern Wis- plants found with greater frequency either in the northern or consin—much more so than it was prior to Euro-American settlement and the Cutover. Aspen is presently the second most abundant forest cover type in northern Wisconsin. Saprophytes are well represented in the Northern Mesic Forest and include beech-drops (Epifagus virginiana), Indian- pipe (Monotropa uniflora), and the coralroot orchids (Coral- lorhiza spp.). Fungi and lichens are also important members of the mesic forests. Several of these are quite specialized and strongly associated with certain tree species or forest developmental stages such as old-growth or older forests (for example, the lichen Lobarion pulmonaria or the fungus hemlock varnish shelf (Ganoderma tsugae). Rare plants strongly associated with Northern Mesic For- est include striped maple (Acer pensylvanicum), broad-leaf sedge, Mingan’s moonwort (Botrychium minganense), little goblin moonwort (B. mormo), blunt-lobed grape fern (B. oneidense), ram’s-head lady’s-slipper (Cypripedium arieti- num), giant rattlesnake-plantain (Goodyera oblongifolia), broad-leaved twayblade (Listera convallarioides), Indian cucumber-root (Medeola virginiana), Smith’s melic grass (Melica smithii), Braun’s holly fern (Polystichum braunii), and heart-leaf foam-flower (Tiarella cordifolia). American ginseng (Panax quinquefolius), a native herb sought in the wild by humans for its reputed medicinal quali- ties, is widespread though generally uncommon or rare in the mesic forests of the north. Ginseng is grown commer- cially in some areas, such as north central Wisconsin in the Forest Transition Ecological Landscape, and seeds obtained from Wisconsin growers (of unknown origin) are sometimes planted in the wild. Some of the rare or otherwise notable animals associated with the mesic forests of northern Wisconsin are gray wolf (Canis lupus), American marten (Martes americana), north- This old-growth stand of mesic hardwood forest features an excep- ern flying squirrel Glaucomys( sabrinus), woodland jumping tionally rich understory. Dominant trees are large sugar maple and American basswood. Representation of older rich hardwood forests mouse (Napaeozapus insignis), hoary bat (Lasiurus cinereus), within Wisconsin’s system of protected areas is almost nonexistent. silver-haired bat (Lasionycteris noctivagans), Northern Gos- The site is an alluvial “tongue” within the drainage of the Bad River. hawk (Accipiter gentilis), Red-shouldered Hawk (Buteo linea- Ashland County, Superior Coastal Plain Ecological Landscape. Photo tus), Black-throated Blue Warbler (Setophaga caerulescens), by Eric Epstein, Wisconsin DNR. Least Flycatcher (Empidonax minimus), four-toed salamander Zone, that is, in the southern parts of the community’s range. This is especially so in the Forest Transition, Northern Lake Michigan Coastal, and Central Lake Michigan Coastal ecological landscapes, where significant to severe fragmentation is the norm. Oddly, in the most northerly of Wisconsin’s ecological landscapes, the Superior Coastal Plain, forest fragmentation is also common due to ownership patterns and farms scattered throughout the areas east and west of the Bayfield Peninsula. In the Northern Lake Michigan Coastal and Central Lake Michigan Coastal ecological landscapes, much of the forest cover has been removed, and the primary cover types and dominant land uses are now agricultural, residential, and industrial. The remaining forests in these regions are highly fragmented, remnant stands are small and isolated, and hard edges constitute the ecotones between developed lands and forests. Invasive plants are widespread and have become common in some of these areas, and sometimes these species dominate the forest understories. Following the slash fires that accompanied and followed the Cutover, the forests in large areas of northern Wisconsin were converted from dominance by older stands of eastern hemlock, sugar maple, yellow birch, eastern white pine, and others to forests dominated by early successional species, especially quaking aspen and white birch. Throughout northern Wisconsin, the changes due to the Cutover and the limited recovery that was allowed to occur in later years have greatly affected stand composition, structure, and function. Across the community’s range, the small scale windthrow events that made up the predominant natural dis- This old-growth stand of northern mesic forest features a diverse turbance regime have been replaced by episodes of periodic canopy of eastern hemlock, sugar maple, yellow birch, American logging. The vast majority of the north’s mesic forests are far basswood, American beech, northern ed oak, and many others. A different today from the forests characteristic of the state supercanopy of huge eastern white pine and an occasional red pine add structural complexity. Menominee County, Forest Transition Eco- prior to Euro-American settlement. logical Landscape. Photo by Eric Epstein, Wisconsin DNR. The forces responsible for these changes include repeated logging episodes, the loss of conifers, the absence of key structural elements such as large trees, snags, and pit-and-mound (Hemidactylium scutatum), wood turtle (Glyptemys insculpta), microtopography, high white-tailed deer populations and and a butterfly, the West Virginia white (Pieris virginiensis). heavy browse pressure, the proliferation of invasive plants, The mesic forests of northern Wisconsin support a high the effects of invasive insects, earthworms, and diseases have diversity of breeding birds (Green 1995), including many for- all contributed to altering the northern forests from their his- est raptors and Neotropical migrants. Given the sheer extent torical condition. of these mesic forests, it’s likely that they support source Historically, a large percentage (50% to almost 70%) of populations for many of our native birds. Herptiles such as Northern Mesic Forest occurred in the older age classes (of frogs and salamanders make heavy use of mesic forests con- 100 years and more). Presently, old stands are now rare range- taining lakes, streams, spring ponds, and especially, ephem- wide, and in Wisconsin undisturbed, old growth stands (“rel- eral ponds. Older, intact stands with abundant coarse woody icts”) are exceedingly so (WDNR 2006). There are legitimate debris, provide excellent habitat for some herptiles and inver- opportunities to address this situation on state and federal tebrates associated with the moist microsites found in the ownerships (and perhaps others) through the public lands downed wood and for mammals finding suitable, sometimes planning process. In most managed stands, there has been a essential, habitat in snags and large living trees. loss, with little provision for recovery, of characteristic and ecologically important structural features such as large living Conservation and Management Considerations trees, large standing snags, large coarse woody debris, pit- Though Northern Mesic Forest remains an abundant natural and-mound microtopography, and a multi-layered canopy. community, dramatic changes to the patterns of forest have In some areas, important trees of low commercial value have occurred in those ecological landscapes bordering the Tension declined or been lost. This formerly included widespread or even locally dominant species such as eastern hemlock or and long-term conservation is feasible. Activities that are American beech. potentially incompatible need to be recognized early on and Important considerations for managers and conservation- addressed by planners, administrators, and members of the ists alike include excessive browse pressure from white-tailed informed public. deer, the impacts of exotic earthworms on soil structure and The ecological and economic importance of Wisconsin’s understory plants, the spread of invasive species such as garlic northern mesic forests is enormous. In aggregate, Northern mustard (Alliaria petiolate), emerald ash borer (Agrillus pla- Mesic Forest was and still is more abundant than any other nipennis), and continued simplification and homogenization natural community, affording unique opportunities to man- of our native forest ecosystems. Many of these factors affect- age at all scales, for the full spectrum of developmental and ing Northern Mesic Forests operate not only at the stand level successional stages, and for most, if not all, of the communi- but also at large scales across entire landscapes. ty’s many distinctive variants. The area occupied by Northern Among the major plant communities of the Upper Mid- Mesic Forest remains vast, and these forests provide viable west, only the mesic forest now exists in sufficient abundance habitat for huge numbers of species (including rarities and and over a wide enough range that that virtually all of its specialists, but also many of the common plants and animals associated species, natural processes, and management pos- we tend to take for granted at present). sibilities are, or could be, accommodated. The management Numerous other natural communities are embedded concerns noted above include the loss or decline of important within a large-scale matrix of northern mesic forest, offering species such as eastern hemlock, yellow birch, eastern white opportunities for dispersal and immigration and, for some pine, Canadian yew, and sensitive herbs; structural elements species and functions, increasing effective stand size. The such as large living trees, large standing snags, large coarse continuous forest cover in many watersheds exerts a positive woody debris, pit-and-mound topography and a multi-lay- influence on water quantity, water quality, and aquatic life in ered canopy; forest fragmentation and the related loss of large northern Wisconsin’s rivers, streams, and lakes (these influ- patches and increase in hard edge; excessive browse from ences extend into the southern reaches of some of our most white-tailed deer; damage to soils and the forest ground layer important and diverse riverine ecosystems), factors that are from exotic earthworms; and invasive plant encroachment. of immense benefit to local and regional economies as well Important plant pests and diseases in the northern forests as to the ecological well-being of the state. include Dutch elm disease (Ophiostoma ulmi), gypsy moth Because Northern Mesic Forest has been classified so (Lymantria dispar), emerald ash borer, and beech bark dis- broadly as a single community, it has been difficult for plan- ease (due to the combined effects of a scale insect and one of ners and conservationists to identify some of the charac- two fungi). The hemlock woolly adelgid Adelge( tsugae) has teristic variations and acknowledge important ecological not yet reached Wisconsin but could have devastating effects differences within the type across its northern Wisconsin on eastern hemlock stands here when and if it arrives. range. The realization that eastern hemlock, historically the Effective incentives are needed that would help owners dominant conifer in many of Wisconsin’s older mesic for- of forested lands protect rare forest variants, developmental ests, had been greatly reduced in abundance after the Cutover stages, or patch sizes. At the very least, this would help balance (especially by those providing raw materials for use by the the impacts of some of the existing incentives, which can pro- tanning industry) led many earlier attempts to protect stands mote simplification, homogenization, and fragmentation. It is of older Northern Mesic Forest to focus on stands in which an increasingly significant conservation need as there are sure eastern hemlock was dominant or well represented. to be conflicts with existing incentive programs that mandate Several of the important variants broadly encompassed harvest or promote early successional forests. On some public within Northern Mesic Forest include the following: lands, such as state and national forests, there have been efforts ■■ Floristically rich, mesic hardwood forests. These have at limited scales to protect the oldest, least disturbed stands. been noted on landforms such as ice-walled lakeplains This remains a valid goal as such stands are so rare, but such and alluvial river terraces with silty soils and high nutri- remnants are all very small (a few hundred acres at most) and ent availability. often have other severe conservation limitations. ■ If they are to be effective, conservation efforts, especially on ■ Some stands with partially impeded drainage and sea- large public holdings where there may be more management sonally high water tables (termed “hydromesic sites” by flexibility, must be broadened to extend protection to floristi- some foresters in Wisconsin) that include characteristics cally rich mesic hardwood forests, unusual or rare mesic for- of Northern Hardwood Swamp intermixed with rich mesic est variants (such as those with an intact eastern white pine hardwood forest elements. Ephemeral ponds may be very supercanopy where American beech or northern white-cedar common in such situations. (Thuja occidentalis) are significant canopy components, and/ ■■ Stands in northeastern Wisconsin in which American or with important internal features such as ephemeral ponds, beech is dominant or co-dominant (these occur on the streams, and rock outcroppings), and to include larger areas Door Peninsula, in parts of the Chequamegon-Nicolet of forest in which restoration of missing or absent features National Forest, and at a few scattered locations elsewhere). ■■ Stands in which conifers such as northern white-cedar, Also see: white spruce (Picea glauca), eastern white pine, and balsam Alverson et al. (1988) fir (Abies balsamea) are well represented in aggregate and Alverson and Waller (1997) occupy a significant part of the forest canopy. Augustine and deCalesta (2003) Bohlen et al. (2004) ■■ Stands in which browse-sensitive plants such as eastern Braun (1950) hemlock, northern white-cedar, Canadian yew, yellow Brown and Curtis (1952) birch, and liliaceous herbs are well represented and stable Brugam et al. (1997) (this is also a management and restoration issue). Canham and Loucks (1984) ■■ Anomalous stands of limited geographic distribution in Davis et al. (1992) which the dominants in older, intact occurrences are often Dunn et al. (1983) eastern hemlock, American beech, red maple, and some- Eckstein (1980) times northern white-cedar. Such stands have been docu- Fassnacht et al. (2015) mented on old dunes and sand ridges near Lake Michigan, Frelich (2002) often, though not always, on the margins of Great Lakes Frelich et al. (1993) embayments. Frelich and Lorimer (1985) Frelich and Reich (1991) To adequately represent “Northern Mesic Forest” from a Frelich and Reich (1996) conservation perspective, examples of each of these variants Frelich and Reich (2003) need to be identified, assessed, and considered for appropri- Goodburn and Lorimer (1998) ate management actions. A good case can be made that these Green (1995) recurring plant assemblages merit recognition as distinct Hale et al. (2006) entities by ecologists and others charged with ensuring that Hale et al. (2008) examples of the natural variability inherent in what we call Harris (1984) Northern Mesic Forest is perpetuated. Harris and Reed (2001) There are excellent opportunities to form or strengthen Lorimer and Frelich (1994) partnerships with managers of “working forests” on federal, Loss et al. (2013) state, tribal, county, and some private lands. It is also neces- Matula (2009) sary, however, to recognize those forest attributes and func- Mladenoff and Stearns (1993) tions that are falling through the cracks and that may not be Mladenoff and Pastor (1993) meaningfully accommodated by current management efforts. Mladenoff et al. (1993) National Council on Science for Sustainable Forestry (2006) Additional Information Powers (2005) For information on related natural communities, see the Powers and Nagel (2008 descriptions of Hemlock Relict, Northern Dry-mesic Forest, Randle (2006) Northern Wet-mesic Forest, Boreal Forest, Southern Mesic Rogers (1981) Forest, and Moist (Wet) Cliff in this chapter. The U.S. National Rooney (2001) Vegetation Classification (US NVC) type corresponding best Rooney (2009) to the more broadly defined Northern Mesic Forest group is Rooney and Waller (2003) CEGL005044 North Central Hemlock – Hardwood Forest Salk et al. (2011) (Faber-Langendoen 2001). Several of the important variants Singer and Lorimer (1997) we have mentioned and attributed to this community and that Stearns (1997) are briefly described above are also recognized as distinct asso- Stearns and Guntenspergen (1987) ciations in the US NVC. Examples include CEGL005008 Sugar Tyrrell and Crow (1994a) Maple – Ash – Basswood Rich Mesic Forest; CEGL002458 Tyrrell and Crow (1994b) Northern Maple – Basswood Forest; and CEGL005042 Great Wiegmann and Waller (2006) Lakes Hemlock – Beech – Hardwood Forest. Woods and Davis (1987)

FROM: Epstein, E.E. Natural communities, aquatic features, and selected habitats of Wisconsin. Chapter 7 in The ecological landscapes of Wisconsin: An assessment of ecological resources and a guide to planning sustainable management. Wisconsin Department of Natural Resources, PUB-SS-1131H 2017, Madison.

For a list of terms used, please visit the Glossary.

For a reference list, please see the Literature Cited.