Progress 10/01/02 to 09/30/04
Outputs
OUTPUTS: The primary objective was to determine the occurrence of species of the red maple Section (Section Rubra) of the genus Acer, red maple (Acer rubrum L.) and its associate silver maple (A. saccharinum L.) in wetland of SE MI. It provides the basis for a model that demonstrates that red maple, from wetland sanctuaries of many kinds of landforms and ecosystems, spread into adjacent upland forests of the 20th century, whereas silver maple is completely absent. In the Washtenaw District of SE MI, research focused on 3 hierarchical levels of landscape ecosystems: Physiographic Systems, Landform-level Ecosystems, and Landscape Ecosystem Types. 204 - 10 x20-m plots were established in 3 Physiographic Systems, Ice-Contact Terrain, Moraine, and Lake Plain that included many distinctive kinds landforms and ecosystem types. Water-wells were established in 2004, and the hydrologic regime was determined for wetlands in Ice-Contact and Moraine Physiographic Systems. The main results were that red maple is a major dominant in remarkably diverse palustrine wetlands within each of the 3 Physiographic Systems. Its average overstory relative dominance was 37.8%, 37.0%, and 18.7% for Ice Contact, Lake Plain, and Moraine Systems, respectively. In contrast, silver maple was dominant primarily in Moraine and Lake Plain Systems. The occurrence of red maple is limited to ecosystems where the hydroperiod is characterized by lack of inundation during the growing season. In such ecosystems, the topsoil is moist or wet throughout the growing season. In contrast, silver maple is restricted to wetlands where the hydroperiod is characterized by inundation well into the growing season followed by a marked drop in the water table in the summer. In ecosystems where inundation did occur during the growing season, its average relative dominance was 84%, 63%, and 85% for Ice Contact, Lake Plain, and Moraine Systems, respectively. Regeneration of red maple is highly limited in wetland ecosystems of each Physiographic System due primarily to the low light irradiance of the vegetation, including the overstory, understory, and ground-cover layers. It is recruited to the understory and overstory only under conditions of high light intensity. Whereas red maple seedlings may be regarded as "understory tolerant" as juveniles, they are highly light requiring as understory and subdominant trees. Overall, the understory tolerance rating is confirmed as Midtolerant. The biodiversity of the ground-cover is markedly greater in red maple swamps than silver maple swamps, and efforts of wetland restoration or management should be aware this important difference. The multi-stem clonal habit and bole forking in the lower 10 m of the bole of overstory trees is pronounced and occurred in virtually every ecosystem. Because of spontaneous asexual regeneration, red maple is a very persistent species once it has become established in either wetland or upland ecosystems. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In conclusion, the research demonstrates the enormously wide variety of wetland ecosystems dominated by red maple in a very small but typical part of its range in Michigan and glaciated eastern North America. These wetlands were either adjacent to or surrounded by dry-mesic or dry ecosystems, which in the absence of fire are colonized by red maple, but never by silver maple. Also, the research provides a model of the overlooked geographic factor that facilitated the successful 20th century invasion by red maple into these dry-mesic and dry ecosystems from its swamp "home." The herbaceous biodiversity in red maple-dominated wetland ecosystems is markedly greater than those dominated by silver maple. In the future, significantly more emphasis is likely to be given to the use red and maple because of its expansion into former oak and pine forests. Therefore, it is important to conserve swamps ecosystems that provide the sanctuary or the ecological "home" for red maple where colonization of adjacent uplands is desirable. In addition, wetland ecosystems of southeastern Michigan which support red maple are highly diverse in herbaceous grOlmd cover, a finding that is similar to reports of red maple-dominated wetlands in the Northeast. Even more important than biodiversity, however, is the ecosystem diversity of wetlands at three hierarchical ecosystem levels--from very broad to very fine-scale units. Therefore, ecosystem management, recognizing that biodiversity is dependent upon ecosystem diversity, is a highly desirable approach in forestland management in eastern North America involving red maple and its associated plants and animals. Impact Statement The research demonstrates the remarkable diversity of red maple and silver maple in ecological systems of broad and fine scales in a tiny portion of the entire North American range of these closely related species of the genus Acer. Conservation of the many kinds of these ecosystems is important to maintain the regional and local gene pools of red maple, which now is the major species colonizing oak and pine uplands throughout eastern North America. Management of entire ecosystems (i.e., ecosystem management), including their total biodiversity, is the ecological basis for sustaining ecosystems and the living Earth.
Publications
- Yocum, M. R. 2005. Occurrence of red maple (Acer rubrum L.) in wetland ecosystems of southeastern Michigan. School of Natural Resources and Environment, University of Michigan, Ann Arbor. 228 pp.
- Lee, J. G. 2005. Landscape ecology of silver maple (Acer saccharum L.) in wetlands of southeastern Michigan. School of Natural Resources and Environment, University of Michigan, Ann Arbor. 181 pp.
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