Date of Graduation

5-2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Biology (PhD)

Degree Level

Graduate

Department

Biological Sciences

Advisor/Mentor

Smith, Kimberly G.

Committee Member

Krementz, David G.

Second Committee Member

Huxel, Gary R.

Third Committee Member

Stephen, Frederick M.

Keywords

Biological sciences; Forest bird community; Forest disturbance; Ice storm damage; Oak woodland restoration; Ozark mountains; Uneven-aged management

Abstract

Forests of the Ozarks are important breeding grounds for many bird species, each with specific habitat requirements. Natural and anthropogenic disturbance events can alter vegetational structure of forests, thereby influencing communities of breeding birds. The objectives of my study were to examine the response of breeding birds and their habitat to three types of forest disturbance: (1) uneven-aged management, (2) ice damage, and (3) woodland restoration. Avian and vegetation surveys were conducted during the 2008, 2009, and 2010 breeding seasons (May-June) in the Ozark National Forest, Arkansas. Each site was surveyed for birds four times a season using fixed-radius point counts. For objective (1), I compared control and thinned plots (n=32 total) immediately after treatment (1994, data from a previous study) and fifteen years post-treatment (2008). Although vegetation differed between treatments in 1994, avian species richness, community composition, and occupancy for three of four populations (representing different nesting guilds) were similar among treatments. Fifteen years later, original differences in habitat had diminished and bird communities were still similar between treatments. For objective (2), I compared sites with high and low ice damage (n=32 total) one year before and two years after a 2009 ice storm. High damage sites had more open canopy and woody debris ground cover, but avian species richness, community composition, and occupancy of three populations (representing different nesting guilds) did not differ between years for either treatment. For objective (3), I compared recently restored woodland and mature forest sites (n=16 total) for three years following restoration (burning and thinning). Restored sites resembled woodland, with open canopy and herbaceous ground cover. They also had higher avian species diversity and more early successional species, cavity-nesters, and some canopy-nesters. These differences diminished with time since fire. Overall, forest bird communities demonstrated resilience to small-scale canopy openings created by uneven-aged management and ice damage. However, when fire was introduced along with thinning, avian communities shifted towards those more typical of open woodland. To maximize habitat availability for the most number of species, managers should plan for areas of both closed-canopy forest and woodland ecosystems.

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