Degree Name

Master of Science (MS)

Semester of Degree Completion

1996

Thesis Director

Thomas A. Nelson

Abstract

I studied the effects of group selection tree harvest on the availability, composition, and use of cavity trees, snags and cavities in the Ozark Mountains of northwestern Arkansas. Sixteen plots dominated by oaks and hickories that were 70-102 years old were surveyed prior to harvest. Tree species, diameter, height and number of visible cavities were recorded. In addition, 192 cavity trees were marked for wildlife observations during the summer and winter. Subsequently, plots were harvested by commercial contractors to either 15 or 19 m2/ha basal area, using either free or structural control thinning methods. A complete survey of all trees was taken after harvest, and observations of wildlife were conducted again.

Prior to harvest, plots averaged 12.2/ha cavity trees, 25.2/ha snags, and 94.3/ha cavities. Cavity trees, snags and cavities declined significantly (P<0.001). after cutting to 4.6/ha, 5.3/ha, and 45.5/ha, respectively. The composition and dbh of cavity trees were not changed by harvest; however, mean height was lower following harvest. The extent of thinning (15 m2 vs. 19 m2) did not affect the density of cavity trees, snags, or cavities. Similiarly, the method used to thin stands (free versus structural control) did not affect the number of cavity trees or cavities remaining; however, the thinning method did affect snag density with fewer snags, using the structural control method.

Wildlife use of marked trees during summer declined after harvest. This is probably due to surveys being conducted shortly after logging, which affects use by recent distrubance. However, winter use increased after cutting, probably because the few cavity trees left after harvest were marked and observances occurred months after initial disturbance. Dbh was the only significant factor influencing use by wildlife both before and after cutting. Blackgum (Nyssa sylvatica), red oak (Quercus rubra), and black walnut (Juglans nigra) were used most frequently and tended to be the most cavity-prone trees.

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