Swine (Sus scrofa) have been introduced into many natural habitats throughout the world, and they have adversely affected the environment in most of those places. Basin marshes are unique, but dwindling ecosystems in Florida that are especially vulnerable to damage by feral swine. We estimated the amount of swine damage to the last remnant of a basin marsh system in Savannas Preserve State Park (SPSP), and to ecotones within the marsh. We also applied an economic valuation method for the swine damage that was based on the dollar amounts that wetland regulators have allowed permit applicants to spend in mitigation attempts to replace lost wetland resources. We found that swine damaged 19% of the exposed portion of the basin marsh in our study area. Seventy percent of the sample sites showed swine damage at the shoreline and 58% showed damage at the interface with the upland vegetation of the adjacent mesic flatwoods. The area damaged within our study site alone was valued between $1,238,760 and $4,036,290. These damage valuation estimates were considered conservative, because it was impossible to incorporate values for such contingencies as swine impact to state and federally listed endangered plants in SPSP, some of which are found nowhere else in the world. We also could not extrapolate an economic quantity to describe the threat posed by the swine inhabiting SPSP as a reservoir for transmission of diseases to domestic livestock.
We monitored cryptic herpetofauna at Savannas Preserve State Park, Florida, by combining artificial cover counts with a quantitative paradigm for constructing and calculating population indices. Weekly indices were calculated from two consecutive days of data collection each week for 7 months from mid-winter to mid-summer in three habitats. Seventeen species were observed at least once, and time trends using index values were followed for six species. Among these, abundance and seasonal pattern information were obtained for an exotic species (greenhouse frog) and a species identified by the Florida Committee on Rare and Endangered Plants and Animals as threatened (Florida scrub lizard). We identified winter as the optimal time in this area to monitor populations for conducting annual assessments. This combined observation and indexing approach could provide managers or researchers with an economical means to quantitatively index population trends for multiple cryptic herpetofauna species simultaneously. Using artificial cover to sample within a population indexing design can be generalized beyond monitoring herpetofauna. Other forms of artificial cover that can be used as observation stations include aquatic artificial substrates, artificial tree cavities, artificial reefs, and other artificial aquatic structures and artificial sea grass units, among many others, and a wide range of taxa are suitable for population monitoring using artificial cover as observation stations in the approach we present, including insects, soil invertebrates, micro and macro aquatic invertebrates, fish, crustaceans, and small mammals.
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