Lakeplain Oak Openings
Lakeplain oak openings are a fire-dependent savanna community, dominated by oaks and characterized by a graminoid-dominated ground layer of species associated with both lakeplain prairie and forest communities. Lakeplain oak openings occur within the southern Lower Peninsula on glacial lakeplains on sand ridges, level sandplains, or adjacent depressions. Open conditions were historically maintained by frequent fire, and in depressions, by seasonal flooding.
County Distribution Map
Global Rank: G2? - Imperiled (inexact)
State Rank: S1 - Critically imperiled
Lakeplain oak openings occur on dune features of sandy lakeplain in southern Lower Michigan. Lakeplain oak openings occur less commonly on silty/clayey glacial lakeplains with seasonally high water tables. Historically, lakeplain oak openings occurred in complex shifting mosaics with wet-mesic flatwoods, southern swamp, lakeplain wet prairie, lakeplain wet-mesic prairie, and mesic sand prairie, depending on water table fluctuations and fire frequency.
Soils are typically mildly alkaline, very fine sandy loams, loamy sands, or sands with moderate water-retaining capacity.
Lakeplain oak openings persist when fire, hydrology, and/or drought prevent canopy closure. The character of lakeplain oak openings can differ dramatically, primarily as the result of varying fire intensity and frequency, which are influenced by climatic conditions, soil texture, topography, and landscape context (i.e., proximity to water bodies and fire-resistant or fire-conducing plant communities). Infrequent, high-intensity fires kill mature oaks and produce openings with abundant scrubby oak sprouts (i.e., oak grubs). Park-like openings, with widely spaced trees and an open grass understory, are maintained by frequent, low-intensity fires, which occur often enough to restrict maturation of oak grubs. Frequent, low-intensity fires also maintain high grass and forb diversity by deterring the encroachment of woody vegetation and limiting single species dominance. Presently, the prevalent catalyst of fires is lightning strike, but historically Native Americans played an integral role in the fire regime, accidentally and/or intentionally setting fire to savanna and prairie ecosystems. In low areas, seasonally high water levels play an important role in maintaining the open condition of lakeplain oak openings.
Dominant canopy species of droughty sand ridges are black oak (Quercus velutina) and white oak (Q. alba). Bur oak (Quercus macrocarpa), pin oak (Q. palustris), and swamp white oak (Q. bicolor) are prevalent on flat, poorly drained areas. Canopy and subcanopy associates of ridges include hickory species (Carya spp.), green ash (Fraxinus pennsylvanica), and sassafras (Sassafras albidum). Canopy associates of swales include green ash, silver maple (Acer saccharinum), red maple (A. rubrum), and cottonwood (Populus deltoides). The ground layer consists of species typical of mesic sand prairie and lakeplain wet-mesic prairie. Ground flora of sandy ridges is characterized by big bluestem (Andropogon gerardii), bluejoint grass (Calamagrostis canadensis), Pennsylvania sedge (Carex pensylvanica), blazing star (Liatris spp.), little bluestem (Schizachyrium scoparium), and Indian grass (Sorghastrum nutans). Shrubs of sandy ridges include serviceberries (Amelanchier spp.), bearberry (Arctostaphylos uva-ursi), New Jersey tea (Ceanothus americanus), sweetfern (Comptonia peregrina), gray dogwood (Cornus foemina), American hazelnut (Corylus americana), hawthorns (Crataegus spp.), huckleberry (Gaylussacia baccata), cherries (Prunus spp.), sumacs (Rhus spp.), dewberry (Rubus flagellaris), and blueberries (Vaccinium spp.). Common ground flora in swales includes bluejoint grass, tussock sedge (Carex stricta), sedge (C. aquatilis), twig-rush (Cladium mariscoides), switch grass (Panicum virgatum), Virginia mountain mint (Pycnanthemum virginianum), and cordgrass (Spartina pectinata). Prevalent shrubs in swales include black chokeberry (Aronia prunifolia), buttonbush (Cephalanthus occidentalis), dogwoods (Cornus spp.), winterberry (Ilex verticillata), shrubby cinquefoil (Dasiphora fruticosa), and willows (Salix spp.).
Lakeplain oak openings and surrounding lakeplain prairie habitat once supported a rich diversity of invertebrates including numerous butterflies, skippers, grasshoppers, and locusts. Mound-building ants and numerous species of grassland birds also thrived in savannas and prairies. The fragmented and degraded status of Midwestern oak savannas and prairies has resulted in the drastic decline of numerous insect and bird species associated with savanna habitats and prairie and savanna host plants. On lakeplains and outwash plains with streams, beaver may have dramatically influenced the landscape by expanding wetland area, preventing the encroachment of woody species in seasonally flooded areas, and creating barriers to fire.
- Agalinis gattingeri (Gattinger’s gerardia, state endangered)
- Agalinis skinneriana (Skinner’s gerardia, state endangered)
- Angelica venenosa (hairy angelica, state special concern)
- Arabis missouriensis var. deamii (Missouri rock-cress, state special concern)
- Aristida longespica (three-awned grass, state threatened)
- Asclepias purpurascens (purple milkweed, state special concern)
- Astragalus neglectus (Cooper’s milk vetch, state special concern)
- Carex richardsonii (Richardson’s sedge, state special concern)
- Lactuca floridana (woodland lettuce, state threatened)
- Leucospora multifida (conobea, state special concern)
- Eupatorium sessilifolium (upland boneset, state threatened)
- Euphorbia commutata (tinted spurge, state threatened)
- Gentiana puberulenta (downy gentian, state endangered)
- Helianthus hirsutus (whiskered sunflower, state special concern)
- Helianthus mollis (downy sunflower, state threatened)
- Hieracium paniculatum (panicled hawkweed, state special concern)
- Hypericum gentianoides (gentian-leaved St. John’s-wort, state special concern)
- Lechea minor (least pinweed, state special concern)
- Leucospora multifida (conobea, state special concern)
- Linum sulcatum (furrowed flax, state special concern)
- Polygala cruciata (cross-leaved milkwort, state special concern)
- Polygonatum biflorum var. melleum (honey-flowered Solomon-seal, presumed extirpated from Michigan)
- Scirpus clintonii (Clinton’s bulrush, state special concern)
- Scleria pauciflora (few-flowered nut-rush, state endangered)
- Scleria triglomerata (tall nut-rush, state special concern)
- Spiranthes ochroleuca (yellow ladies’-tresses, state special concern)
- Sporobolus clandestinus (dropseed, state special concern)
- Tradescantia virginiana (Virginia spiderwort, state special concern)
- Ammodramus savannarum (grasshopper sparrow, state special concern)
- Atrytonopsis hianna (dusted skipper, state threatened)
- Cryptotis parva (least shrew, state threatened)
- Dendroica discolor (prairie warbler, state endangered)
- Elaphe o. obsoleta (black rat snake, state special concern)
- Elaphe vulpina gloydi (eastern fox snake, state threatened)
- Erynnis baptisiae (wild indigo duskywing, state special concern)
- Erynnis p. persius (Persius duskywing, state threatened)
- Euphyes dukesi (Duke’s skipper, state threatened)
- Lepyronia gibbosa (Great Plains spittlebug, state threatened)
- Lycaeides melissa samuelis (Karner blue, federal endangered and state threatened)
- Microtus ochrogaster (prairie vole, state endangered)
- Papaipema maritima (maritime sunflower borer, state special concern)
- Papaipema sciata (Culver’s root borer, state special concern)
- Papaipema silphii (silphium borer moth, state threatened)
- Prosapia ignipectus (red-legged spittlebug, state special concern)
- Sistrurus c. catenatus (eastern massasauga, federal candidate species and state special concern)
- Spartiniphaga inops (spartina moth, state special concern)
- Terrapene c. carolina (eastern box turtle, state special concern)
Biodiversity Management Considerations
Use of prescribed fire and restoration of hydrologic processes is imperative for maintaining an open canopy, promoting high levels of grass and forb diversity, and deterring the encroachment of woody vegetation and invasive species. Filling of ditches can contribute to the restoration of hydrologic processes. Fire intervals of one to three years bolster graminoid dominance, increase overall grass and forb diversity, and remove woody cover of saplings and shrubs. Where rare invertebrates are a management concern, burning strategies should allow for ample refugia to facilitate effective post-burn recolonization. Where feasible, fire management of lakeplain oak openings should include burning adjacent lakeplain prairies and other fire-dependent community types. Degraded lakeplain oak openings that have been long deprived of fire often contain a heavy overstory and understory of shade-tolerant species such as red maple and green ash, which can be removed by mechanical thinning, herbiciding, or girdling. Restored sites can be maintained by periodic prescribed fires and may require investment in native plant seeding where seed and plant banks are inadequate.
Monitoring and control efforts to detect and remove invasive species are critical to the success of restoration projects. Invasive species that threaten the diversity and community structure of either the dry beach ridges or wet swales of lakeplain oak openings include spotted knapweed (Centaurea stoebe), common St. John’s-wort (Hypericum perforatum), black swallow-wort (Vincetoxicum nigrum), white swallow-wort (V. rossicum), Japanese knotweed (Fallopia japonica), Kentucky bluegrass (Poa pratensis), Canada bluegrass (P. compressa), ox-eye daisy (Leucanthemum vulgare), hawkweeds (Hieracium spp.), sheep sorrel (Rumex acetosella), hoary alyssum (Berteroa incana), reed (Phragmites australis subsp. australis), reed canary grass (Phalaris arundinacea), narrow-leaved cat-tail (Typha angustifolia), hybrid cat-tail (Typha xglauca), purple loosestrife (Lythrum salicaria), Oriental bittersweet (Celastrus orbiculatus), common buckthorn (Rhamnus cathartica), glossy buckthorn (Frangula alnus), autumn olive (Elaeagnus umbellata), Eurasian honeysuckles (Lonicera morrowii, L. japonica, L. maackii, L. tatarica, L. xbella, and L. xylosteum), and multiflora rose (Rosa multiflora).
Native Americans utilized dune ridges on the lakeplain for settlements and trails, and it is quite likely that fires resulting from this use periodically spread to adjacent oak openings and prairies. Most lakeplain oak openings were cleared for agriculture, and either residential or industrial development. Within the few remnant lakeplain oak openings, alterations of groundwater hydrology and fire suppression have resulted in increased encroachment by woody species and succession to shrub and forest communities. Absence of fire in lakeplain oak openings causes decreased herb diversity, increased canopy and subcanopy cover, invasion of fire-intolerant species, and ultimately the formation of a closed-canopy oak community, often within 20 to 40 years. The hydrologic regime of the lakeplain and lakeplain oak openings has been drastically altered. Many lakeplain landscapes are artificially ditched and drained. Beaver activity has been eliminated in these systems for nearly 200 years.
There are two prominent forms of lakeplain oak openings that occur interspersed through ridge and swale topography. In both types, oaks dominate the tree canopy layer, and grasses and sedges make up the majority of the ground layer. The dry-mesic type occurs on droughty beach ridges and is typically dominated by black oak and white oak. The wet-mesic type, found on flat, poorly drained areas, is dominated by bur oak, pin oak, and swamp white oak, with a ground layer similar to lakeplain wet prairie and lakeplain wet-mesic prairie.
Similar Natural Communities
Lakeplain wet prairie, lakeplain wet-mesic prairie, wet-mesic sand prairie, mesic sand prairie, wet-mesic flatwoods, bur oak plains, oak openings, dry-mesic southern forest, dry sand prairie, dry southern forest, oak barrens, oak-pine barrens, and wooded dune and swale complex.
- Cohen, J.G. 2001. Natural community abstract for lakeplain oak openings. Michigan Natural Features Inventory, Lansing, MI. 9 pp.
- Faber-Langendoen, D., and P.F. Maycock. 1987. Composition and soil environment analysis of prairies on Walpole Island, southwestern Ontario. Canadian Journal of Botany 65: 2410-2419.
- Hayes, B.N. 1964. An ecological study of wet prairie on Harsens Island, Michigan. Michigan Botanist 3: 71-82.
- Nuzzo, V. 1986. Extent and status of Midwest oak savanna: Presettlement and 1985. Natural Areas Journal 6(2): 6-36.
For a full list of references used to create this description, please refer to the natural community abstract for lakeplain oak openings.
Kost, M.A., D.A. Albert, J.G. Cohen, B.S. Slaughter, R.K. Schillo, C.R. Weber, and K.A. Chapman. 2007. Natural Communities of Michigan: Classification and Description. Michigan Natural Features Inventory, Report No. 2007-21, Lansing, MI.