Graduation Year

2010

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Biology

Major Professor

Thomas Crisman, Ph.D.

Keywords

Treefrog, Wetland, PVC, O. septentrionalis, Temporal

Abstract

Wetlands in densely urbanized landscapes display altered physical, chemical, and biological features; however, long term trends in these are poorly known. The purpose of this study was to determine if biological, physical, and chemical changes in isolated cypress domes are related to time since incorporation within an urban landscape. Sixteen cypress domes in Tampa, Florida were placed into four decadal age groups based on construction date of residential homes within 200 m of wetland edge, with multiples in each age group: 1970s, 1980s, 1990s, 2000s, and rural sites as regional controls. Each site was visited monthly from July 2008 until July 2009. Hylid treefrogs were monitored using PVC refugia and mating calls. Non-hylid anuran species were monitored using mating call surveys and pitfall traps.

Hydrology, pH, and conductivity were recorded, transects were made once at each site from wetland center to terrestrial edge in all four cardinal directions, and all trees greater than 8cm DBH were identified and measured for basal area. The dominant treefrog captured was the exotic O. septentrionalis, which was significantly more abundant in 1990s urban cypress domes than either rural sites or other urban decadal groups. The number of both the exotic O. septentrionalis and the native H. cinerea were positively correlated to more recent decades of development surrounding wetlands. H. squirella was detected at sites where O. septentrionalis was rare, and H. femoralis was found almost exclusively at rural sites. Hydroperiods of all urban cypress domes were three times longer on average than rural sites, and conductivity was significantly elevated at all urban sites.

In cypress domes within the 1970s decade group, the relative abundance of Florida "facultative wet" tree species was greater than "obligate wet" tree species suggesting encroachment of Acer rubrum into cypress domes possibly due to decades of fire exclusion. At these long isolated sites exotic plants such as Sapium sebiferum were most abundant. Results indicate rapid changes in both physico-chemical characteristics and anuran composition, and long term effects of decreased treefrog abundance and altered tree community structure following incorporation within the urban landscape.

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