|Title||Ecosystem mediated occurrence and recruitment of Northern Red Oak (Quercus rubra L.) in northern lower Michigan|
|Year of Publication||2003|
|Academic Department||School of Natural Resources and Environment|
|Degree||Master of Science|
|Number of Pages||163 pp.|
|University||University of Michigan|
|City||Ann Arbor, MI|
Although significant declines in northern red oak (Quercus rubra L.) occurrence have been recorded on both mesic and dry sites over much of its range, localized regeneration is common where a seed source is present and site conditions favor its growth. The multi-factor classification of landscape ecosystems at the University of Michigan Biological Station (UMBS), in northern Lower Michigan, provided a site-specific context to assess the occurrence and recruitment of red oak over a range of site conditions within one local area. The occurrence of northern red oak was determined and compared for 16 upland ecosystem types nad 8 wetland types in outwash plain and moraine physiographic systems. Ecosystem factors that affect red oak occurrence were compared for six representative types of the inter lobate moraine, deep outwash plain over interlobate moraine, and high-elevation outwash plain landforms. Discriminant analysis integrating physiographic, soil, and vegetative variables confirmed the ecological distinctness of these ecosystems. Red oak comprised 15% - 45% of the basal area of the overstory layer in the dry, high-elevation outwash plain and dune ecosystems, but it was poorly represented in the understory. Its occurrence was low in all layers in more-mesic ecosystem types on the outwash plain and interlobate moraine landforms. A major exception to the poor overall recruitment of red oak was in a deep outwash plain over interlobate moraine ecosystem (type 59) where it comprised over 50% of the understory density and nearly half of the basal area. The combined influence of seed source, fine textured soil banding, and high available light beneath the patchy overstory facilitated oak recruitment despite the deer browsing. A study of red oak occurrence and recruitment among a series of four clearcut and burned areas in a dry outwash plain ecosystem indicated that many of the red oaks in all vegetative layers within the four treatments occurred in multi-stemmed clones. Recruitment following cutting and burning was probably limited root collar sprouts of cut or burned individuals. The red oak overstory at UMBS established under considerably different conditions (i.e., logging, repeated fires, and low density of deer) than what exist today. The occurrence of red oak in the overstoy is the legacy of its presettlement occurrence and the logging and post-logging fires.