Utilizing Plethodontid Occupancy to Assess Initial Ecosystem Responses to Invasive Plant Control Treatment in Central Hardwoods

This data reflects occupancy sampling of Plethodontid salamanders in West Virginia, USA across lands treated for invasive plant control. We hypothesized negative impacts on odds of salamander occupancy on treated sites due to loss of vegetative structure and increased predation risk. Our data identified decreased occupancy odds on treated sites, decreased occupancy odds on sites with lower canopy cover, and high interspecific variation in occupancy. Our results reflect potential indirect damage to Plethodontids and correlated ecosystem services from invasive plant control efforts. We collected vegetation and salamander data across 60 sites in West Virginia, USA, across 12 sampling occasions. Vegetation sampling was completed once and included vegetation data in 0.02 ha plot. Salamander sampling took place within the same plot, and included the use of visual and coverboard sampling, completed 12 times at each site. We also measured observation level variates, such as soil temperature at the time of sampling. We used a single-season, single-species occupancy model to test hypotheses, using the "unmarked" package in RStudio. To include multiple species, we coded each species as a factor with its own occupancy intercept. Additionally, to address a potential closure assumption violation, we coded Season as a covariate to observe occupancy odd differences between 'Spring' and 'Fall' sampling. The 'Treatment' covariate in our modeling is a binary covariate, meaning sites were simply treated for invasive species (1), or did not receive treatment (0). Therefore, while we see a decrease in occupancy odds between treated and untreated sites, we do not know what is driving this difference. Herbicide impacts, loss of vegetative structure, increased predation risk, or a combination of these could all be driving a larger 'Treatment' effect.