Date of Award

Fall 12-1-2006

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Geography, Geology, and Anthropology

First Advisor

James H. Speer

Second Advisor

Marion T. Jackson

Third Advisor

Ryan R. Jensen

Abstract

During the course of 25 years, plant specimens from several local locations have been collected and deposited into the Indiana State University (ISU) Herbarium by plant taxonomy students. The locations of some of these plots were reestablished in the spring of 2004. In each plot, all woody and spring herbaceous plants were collected from 26 February 2004 to 12 May 2004. These specimens were identified and compared to previous collections to examine species change in the context of gap dynamics. I compiled a species list for each plot and each preserve. Objectives for this thesis were to document plant diversity changes, to examine species richness for herbaceous and woody species, and to document disturbance patterns at Forest Park in Vigo County, Indiana. In total, I identified 70 families, 126 genera, and 222 species. I examined species to area relationships and found that larger plots do not have greater species diversity. I found a significant increase in diversity of spring ephemerals at the species level. Most plots had some exotics and those plots with gaps tended to have a greater number of exotics. Coefficient of conservatism values and floristic quality indices were calculated for each site. Forest Park had higher values than Kieweg suggesting that it more closely resembles pre-settlement forest conditions. Dendrochronological techniques were used to quantify canopy gaps in Forest Park to determine the effect of this disturbance on spring ephemeral diversity. Canopy gaps were selected within six plots. Climate data (temperature and precipitation) was used to visually determine if years of suppression were due to climate rather than gap effects. Release and suppression criteria were used to identify canopy gaps and tree responses. Large rings were also recorded for a better measure of tree response. Canopy gaps as recorded by ring-width release were compared to plant diversity data through time. Gaps were mainly created by one tree and were on average 337 m2 in size. An increase in the number of gaps resulted in a decrease in species diversity, but no change was detected with gap area. An increase in the number of gaps appears to increase the number of exotic species, but as gap area increases, exotics tend to decrease. Single or a series of large rings were better at recording gap events than the modified Lorimer and Frelich gap criteria. Shade tolerant trees respond more frequently to gap events than shade intolerant trees. On average, Acer saccharum experienced three major gap events in their lifetime and are sensitive to gap dynamics with numerous suppressions and releases in the trees. Fagus grandifolia is also sensitive to gap dynamics residing in the understory for several years. All other species are slightly sensitive to canopy gaps, with some rarely if ever recording them in their tree rings.

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