Regional Landscape Ecosystems of Michigan, Minnesota, and Wisconsin
SUB-SUBSECTION VII.1.1. Standish
DISCUSSION: Sub-subsection VII.1.1 is a flat clay and sand lake plain, part of the Saginaw lake plain to the south. The sub-subsection is separated from the remainder of the Saginaw lake plain because of its shorter growing season, which results in significant differences in forest vegetation and in human land use.
ELEVATION: 572 to 850 feet (174 to 259 m).
AREA: 1,359 square miles (3,520 sq km).
STATES: Michigan.
CLIMATE: See subsection.
BEDROCK GEOLOGY: Glacial deposits are up to 250 feet thick, but localized exposures of Mississippian age bedrock occur throughout Arenac County at the northern edge of the sub-subsection (Akers 1938). Glacial drift thicknesses are 50 feet or less along the shoreline throughout the entire sub-subsection.
Sub-subsection is underlain by Mesozoic (Jurassic) and Paleozoic (Pennsylvanian and Mississippian) bedrock (Dorr and Eschman 1984, Milstein 1987). Jurassic red beds, consisting mainly of sandstone, shale, and clay, with minor beds of limestone and gypsum, are located beneath the inland margin of Sub-subsection VII.1.1. Pennsylvanian sandstone, shale, coal, and limestone underlie the southern part of the sub-subsection; Mississippian limestone and gypsum are to the north. Gypsum is mined at Alabaster in the north.
LANDFORMS: Sandy lacustrine deposits far exceed lacustrine silts and clays. The northern third of the sub-subsection is a large glacial delta, which has thick, droughty sand soils. The Au Sable and Rifle Rivers have created deep, steeply eroded gorges through the thick sands (Dorr and Eschman 1984, Burgis 1977).
The lacustrine sand plain to the south is a mosaic of large, poorly drained basins and flat, droughty plains. The elevational differences between the poorly drained basins and excessively well drained plains can be a matter of just a few feet.
The poorly drained basins can be several miles in area. Many of the basins contain thin peat soils, which have probably accumulated in the last 3,000 to 4,000 years. Small, steeply sided, transverse dune ridges occur throughout these embayments; these ridges probably formed when meltwater streams were depositing abundant sands into the shallow embayments of the pro-glacial lakes.
Intermediate drainage conditions between the very poorly drained basins and the excessively well drained plain occurr over large areas. The soils of these areas are generally poorly drained, with indications that both windthrow and fires were common.
Fine-textured lacustrine deposits and fine-textured moraines, reworked by water, are concentrated along the inland and lake margins of the sub-subsection.
LAKES AND STREAMS: Most of the few lakes in the sub-subsection are concentrated within small areas of end moraine and ice-contact topography. Tawas Lake occupies an old embayment of Lake Huron, separated from Saginaw Bay by numerous beach ridges. Several large rivers are concentrated on the sand lake plain, including the Au Sable, Au Gres, Rifle, Tittabawassee, Molasses, and Pine.
SOILS: Soil drainage conditions are discussed in the LANDFORMS section; most of this discussion concerns the sandy part of the sub-subsection. The predominant drainage classes on the sand lake plain are very poorly, poorly, and excessively well drained. Predominant drainage classes on the clay and clay loam soils of the lake plain include poorly drained, moderately well drained, and well drained. The soils on the small areas of ground and end moraine are primarily moderately well drained or well drained loams and clays. Soils of the sub-subsection are classified as gently sloping Haplaquepts plus Haplaquods (USDA Soil Conservation Service 1967).
PRESETTLEMENT VEGETATION: On the droughty delta deposits along the Au Sable River, jack pine barrens were the dominant vegetation, with white pine, red pine, and some black oak and white oak on fire-protected sites (Comer et al. 1993a, b). Other areas of dry sand plain also supported jack pine-northern pin oak barrens.
Large abandoned embayments, several miles inland from the present Saginaw Bay shoreline, supported bogs or shrub swamps with stunted trembling aspen or jack pine. The transverse dune ridges supported open oak-pine woodlands, with white pine, red pine, white oak, black oak, and bigtooth aspen.
Flat areas of the sand lake plain with poorly drained or somewhat poorly drained mineral soils supported forests of white pine, red maple, and trembling aspen. On the flat, sandy lake plain were numerous swamp types, including swamps dominated by northern white-cedar, tamarack, black ash, hemlock, white pine, and maple, and combinations of these species.
Well-drained sites on the flat clay plain supported forests of hemlock and beech, sugar maple, and basswood. Hemlock and white pine increased on more poorly drained sites. On poorly drained sites on the clay plain, there were also extensive tamarack swamps, cedar swamps, black ash swamps, and maple swamps, as well as shrub swamps dominated by speckled alder and willow.
Loamy or clayey soils on the flat ground or end moraines supported forests of hemlock and northern hardwoods with sugar maple, beech, white pine, and hemlock. The fine-textured end moraine located just west of Tawas has sandy soils on its surface. It supported jack pine barrens and open, burned-over grasslands.
Along the present shorelines of Saginaw Bay were extensive areas of swamp forest, wet prairie, and coastal marsh. The swamp forests supported both hardwood and conifer species. Marshes were most extensive at the mouths of the Rifle and Pine Rivers in Arenac County, where there was also wet prairie. Several of the embayments contained wide complexes of parallel beach ridges and swales. The swales were dominated by aquatic macrophytes or swamp forest; the ridges were dominated by a diverse mix of hardwoods and conifers. The higher beach ridges near the lake shore were dominated by white pine and red oak.
NATURAL DISTURBANCE: Windthrow was common in the forests near the Great Lakes shoreline, resulting from a combination of strong winds off Lake Huron, flat topography, and poor drainage conditions. Water level fluctuations along the Great Lakes shoreline resulted in cyclical floristic variation within the coastal marshes and extensive mortality within the coastal swamp forests.
In the GLO survey, fire was noted as common on the jack pine-dominated barrens of the Au Sable River delta.
PRESENT VEGETATION AND LAND USE: Agricultural land use is less intensive on this part of the lake plain than in sub-subsections further south because of both colder climatic conditions and a prevalence of sandy soils. Drainage ditches have been constructed on both the clay lake plain and on the flat parts of the loamy or clayey ground and end moraines. Clay soils on the lake plain are used as pasture. Moraines are farmed for both row crops and pasture. No examples of mature forest are known in either the clay lake plain or the fine-textured moraines. Sandy soils have been less intensively converted to agriculture than other portions of lake plain further south.
Much of the poorly or excessively drained lake plain is managed for either timber or recreational use. The delta of the Au Sable is managed largely by the Huron National Forest for timber. Both jack pine and red pine plantations cover much of the delta.
A large strip mine is located near Alabaster. Urban development in this sub-subsection is most intensive around Tawas, Standish, and Au Gres.
Native vegetation, bogs and shrub swamp, persists on the poorly drained, abandoned embayments on the lake plain. Upland vegetation on the transverse dune ridges of these embayments has changed considerably; white oak, black oak, and bigtooth aspen persist, but white pine and red pine are generally lacking.
The jack pine-dominated barrens of the Au Sable River delta have been converted to closed-canopy plantations of jack pine or red pine.
Some of the swamps along the Lake Huron shoreline have been converted to agriculture, but those that persist appear to have forest compositions relatively similar to those recorded by GLO surveyors.
Many of the marshes along Lake Huron have been manipulated for waterfowl management, and dikes have been constructed for water control. Small areas of marsh remain intact. Small remnants of prairie may also exist here.
Boat slips and channels have also been constructed along many sections of shoreline, resulting in varying degrees of marsh destruction.
RARE PLANT COMMUNITIES: Small areas of wet prairie (lakeplain prairie) may persist.
RARE PLANTS: Cirsium pitcheri (Pitcher's thistle).
RARE ANIMALS: Chlidonias niger (black tern).
NATURAL AREAS: Michigan Nature Association Preserve: Frink's Pond.
PUBLIC LAND MANAGERS: National Forests: Huron; State Forests: Au Sable; State Parks: Harrisville, Tawas Point; State Wildlife Areas: Wigwam Bay; State Environmental Areas: Rifle River, Pine River, White's Beach.
CONSERVATION CONCERNS: The jack pine plains along the lower Au Sable River have been considered for expansion of habitat for the Kirtland's warbler. A few of the shallow peatlands on the sand lake plain have undergone little intensive forest management and appear to be of potential natural area quality; however, little detailed biological information is available.
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