Date of Award

Summer 8-1-1984

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Life Sciences

First Advisor

Marion T. Jackson

Second Advisor

John O. Whitaker Jr.

Abstract

Magnolia tripetala L. occurs in Indiana as a disjunct from the Appalachian mountains populations. Currently, the known distribution of ~· tripetala in Indiana is confined to seven sites in Crawford County. The current status of ~· tripetala and the surrounding plant community was evaluated to aid in the future study, protection and management of this species, which is endangered in Indiana. Systematic random sampling of the tree stratum was done with belt transects. The sapling and seeding strata were sampled with subplots, placed along the belt transects. Permanent plots were established to enable future monitoring of what is currently prime habitat for M. tripetala. Flowering success rates and germination success were determined for M. tripetala. A species list was compiled for the study site. The tree stratum was found to be dominated by Acer saccharum Marsh., Fagus grandifolia Ehrh., ~· tripetala and~ rubrum L. The sapling and seedling strata were predominately composed of A. saccharum and A. rubrum. The high densities of ~· tripetala stems in the lower size classes and the sapling stratum indicate that reproduction is sufficient to maintain or expand the populations in Indiana. The lower percent importance for ~· tripetala in the seedling stratum reflects the clonal reproductive strategy of this species. Throughout its range, ~· tripetala is associated with moist soils and shaded ravines. The influence of topography at the study site iv was shown for several species, including ~· tripetala. Magnolia tripetala densities were higher on the more mesic exposures. Slopes at the bases of cliffs had a higher percentage of soil moisture than the corresponding exposures without cliffs. Magnolia tripetala reproduction, as indicated by sapling and seedling densities, was higher for most exposures with cliffs. Flowering sequence was shown to influence the fruiting success of M. tripetala. The later blooming flowers had a much higher percent fruit-set than early blooming flowers. The temporal separation of I stigmatic receptability and anthesis prevents the self-pollination of an individual flower. Self-compatibility between different flowers on the same plant was observed. However, fruiting success was lower for self-pollinated flowers than for flowers pollinated by other plants from the same ravine and plants from other ravines. The fruiting success rates may be linked to genetic similarity. Permanent plots were located at sites of prime ~· tripetala habitat. The permanent plots were also placed to include sites where Ailanthus altissima (Mill.) Swingle has become established. If trends continue, ~· al tissima may become a successful competitor with ~· tripetala. Monitoring of the permanent plots will help in future management decisions for the study site. One hundred fifty-seven vascular plant species were identified from the study site. Several species of special concern are well established in all ravines surveyed. The plant community as a whole is unique for Indiana and deserves future protection from man-made disturbances.

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