Feral swine damage to globally imperiled wetland plant communities in a significant biodiversity hotspot in Florida

Abstract

We studied rooting damage during five-years of feral swine control at Avon Park Air Force Range, a significant botanical biodiversity hotspot in peninsular Florida with many globally imperiled plant species and communities. While control reduced swine abundance, remaining animals consistently rooted the 49 studied sites in both middle-dry season (MDS) and late-dry season (LDS) each year. At each study site, we measured rooting with sub-meter accuracy. Neither total nor proportional area rooted differed in either season, across study years, or among plant community types: herbaceous seepage slopes, wet pine savannas, wet grasslands. The proportion of sites with damage during MDS was at least 25 % less than pre-control baseline. During LDS, the proportion of sites with damage increased over years but remained below the initial 2 years' MDS results. Fresh rooting frequency (rooting \1 week-old) across sites dropped precipitously from baseline and remained low for MDS. Fresh rooting frequency among sites during LDS was lower than MDS for all but year two of the study. Canopied habitat \50 m from a study site almost guaranteed rooting at the site each observation period. We propose actions for protecting wetlands, integrating swine control into other compatible land use practices, and improving swine control efficacy. While we measured damage amounts at each site very accurately, our approach of also considering frequency of rooting and frequency of fresh rooting across sites offers low-labor means to broadly assess swine damage and control Communicated by

Patterns of Non-Native Species Introduction, Spread, and Ecological Impact in South Florida, the World's Most Invaded Continental Ecoregion

“…People move to Miami from around the globe, acting as accidental (or intentional) dispersal agents. This has been the case since the early days of European colonization when Old World species were introduced with early settlers (Mack et al 2000), as is the case with feral pigs (Sus scrofa), which were introduced to Florida in the 1500s (Engeman et al 2016). The high volume of imported flora and fauna to global shipping ports in South Florida, such as the Port of Miami, creates more opportunities for non-native species to enter the local environment, and the increased accessibility of new source pools due to global trade expansion increases the total number of imported species (Seebens et al 2018).…”

Invasive Wild Pigs: A Significant Disturbance in Coastal Forests

“…Over time, these alterations to spatial distribution, regeneration, and recruitment of species can influence the canopy of a forest, as it can effectively halt the establishment of new young trees [63]. Additionally, the impacts of foraging by wild pigs can result in the local extinction of plant species [7,61,[64][65][66][67]. Local extinctions permanently alter the composition of the plant community, which can have significant and cascading impacts on the health and function of the ecosystem [7,68].…”

“…As discussed earlier, wild pigs are extremely opportunistic omnivores that will exploit high-value resources. As a result, pig-rooting, as a foraging technique, often leads to significant alterations to spatial distribution, reductions in plant cover, reproduction, and growth, and can contribute to local extinction; all of these impacts reduce competition for resources and increase the available space for invasive plants to become established in [7,61,64,66,69,77]. Similarly, the impacts of wild pigs on vegetative regeneration may also facilitate the establishment of invasive plant species by reducing competition and opening canopy cover in extreme cases [63,69].…”

Invasive feral swine damage to globally imperiled steephead ravine habitats and influences from changes in population control effort, climate, and land use

“…An economic perspective examining swine damage costs of steephead ravines provides useful information for documenting the need and validating the application of fiscal and human resources for protecting EAFB's natural treasures. Economically assessing damage requires placing a value on damage, which has been carried out for a variety of wetlands in Florida using expenditure data from Environmental Protection Agency (EPA) permitted mitigation projects (Engeman et al 2004(Engeman et al , 2016bKing 1998). These data provide an empirical, defensible, logical valuation for damaged wetland habitats, including previously at EAFB for feral swine damage to seepage slopes (Engeman et al 2007).…”

“…Because steephead ravines' wetland habitats are rare, they are not expressly enumerated among categories provided by King (1998). Thus, as for previous swine damage valuations for unique and rare wetlands in Florida (e.g., Engeman et al 2007Engeman et al , 2016b, we applied the median figure from King (1998) over freshwater wetland types (excluding prairie potholes) as an empirical "willingness to pay" value for restoration. The restoration cost estimate at the time of our final damage assessment in 2013, and after adjusting for 3% annual inflation rate since King (1998) presented the values, was $491,775/ha (King 1998;Zerbe and Dively 1994).…”