Conservation of Terrestrial Salamanders Through Hemlock Woolly Adelgid Management in Eastern Hemlock Forests within Great Smoky Mountains National Park

Hemlock woolly adelgid (Adelges tsugae; HWA), an invasive aphid-like arthropod, was first documented on the east coast of the United States in the 1950s. HWA is an herbivore which primarily feeds at the needle base of hemlock tree species (Pinaceae: Tsuga). With no evolutionary defenses and few biotic controls, the eastern and Carolina hemlock (Tsuga canadensis and Tsuga carolinensis) serve as the primary diet of HWA in eastern North America. The invasive pest began to spread rapidly throughout the hemlock’s range causing defoliation and death of the trees within 4 – 10 years. With the loss of the foundational species, Tsuga canadensis, several microenvironmental changes were documented. Microenvironmental changes in response to biological invasions and anthropogenic forestry practices can lead to shifts in populations of physiologically sensitive taxa such as salamanders and their prey, terrestrial arthropods. National Park Service staff at Great Smoky Mountains National Park manage HWA by treating eastern hemlocks with the neonicotinoid pesticides, imidacloprid and dinotefuran. To measure indirect effects of eastern hemlock mortality, and HWA management, this study measured several parameters in hemlock-dominated stands that have been repeatedly treated by the NPS and stands which were untreated and where hemlock woolly adelgid has reduced the hemlock canopy. Our major objectives were to assess microenvironmental and vegetative community differences between managed and un-managed eastern hemlock stands and analyze those differences with respect to arthropod and woodland salamander abundance and/or diversity. A mixed effects ANOVA was used to compare mean soil organic matter (or duff) pH, substrate volumetric water content, vegetative litter depth, temperature, and arthropod diversity and abundance between managed and un-managed stands. A mixed effects linear model using elevation range as a random effect or block was used to model salamander abundance with the aforementioned continuous variables. While the microenvironmental parameters were not significantly different between stand types, order-level richness of arthropods, and woodland salamander abundance did significantly differ (α = 0.05). According to the linear mixed effects model, substrate moisture and forest management were the strongest predictors of salamander abundance (α = 0.05)

Application of advanced techniques for the remote detection, modelling and spatial analysis of mesquite (prosopis spp.) invasion in Western Australia

Invasive plants pose serious threats to economic, social and environmental interests throughout the world. Developing strategies for their management requires a range of information that is often impractical to collect from ground based surveys. In other cases, such as retrospective analyses of historical invasion rates and patterns, data is rarely, if ever, available from such surveys. Instead, historical archives of remotely sensed imagery provides one of the only existing records, and are used in this research to determine invasion rates and reconstruct invasion patterns of a ca 70 year old exotic mesquite population (Leguminoseae: Prosopis spp.) in the Pilbara Region of Western Australia, thereby helping to identify ways to reduce spread and infill. A model was then developed using this, and other, information to predict which parts of the Pilbara are most a risk. This information can assist in identifying areas requiring the most vigilant intervention and pre-emptive measures. Precise information of the location and areal extent of an invasive species is also crucial for land managers and policy makers for crafting management strategies aimed at control, confinement or eradication of some or all of the population. Therefore, the third component of this research was to develop and test high spectral and spatial resolution airborne imagery as a potential monitoring tool for tracking changes at various intervals and quantifying the effectiveness of management strategies adopted. To this end, high spatial resolution digital multispectral imagery (4 channels, 1 m spatial resolution) and hyperspectral imagery (126 channels, 3 m spatial resolution) was acquired and compared for its potential for distinguishing mesquite from coexisting species and land covers.These three modules of research are summarised hereafter. To examine the rates and patterns of mesquite invasion through space and time, canopies were extracted from a temporal series of panchromatic aerial photography over an area of 450 ha using unsupervised classification. Non-mesquite trees and shrubs were not discernible from mesquite using this imagery (or technique) and so were masked out using an image acquired prior to invasion. The accuracy of the mesquite extractions were corroborated in the field and found to be high (R2 = 0.98, P36 m2 (66-94%) with both approaches and image types. However, both approaches used on the hyperspectral imagery were more reliable at capturing patches >36 m2 than the DMSI using either approach. The lowest omission and commission rates were obtained using pairwise separation on the hyperspectral imagery, which was significantly more accurate than DMSI using an overall separation approach (Z=2.78, P36 m2. However, hyperspectral imagery processed using pairwise separation appears to be superior, even though not statistically different to hyperspectral imagery processed using overall separation or DMSI processed using pairwise separation at the 95% confidence level. Mapping smaller patches may require the use of very high spatial resolution imagery, such as that achievable from unmanned airborne vehicles, coupled with a hyperspectral instrument. Alternatively, management may continue to rely on visual airborne surveys flown at low altitude and speed, which have proven to be capable at mapping small and isolated mesquite shrubs in the study area used in this research