A study is being conducted to examine the impact of an invasive pest and the chemicals utilized to combat it on the wildlife inhabiting aged hemlock forests.
The hemlock woolly adelgid (HWA) has been causing significant damage to forests in southwestern Nova Scotia for nearly ten years. Efforts to control its spread have involved the application of insecticides such as imidacloprid and dinotefuran by Parks Canada, the provincial government, local groups, and private landholders.
However, Mathilde Christjansen, a master’s student at Mount Allison University in Sackville, N.B., highlighted the limited understanding of how the woolly adelgid and the insecticides employed against it are impacting other species. Christjansen emphasized that while imidacloprid targets insect nervous systems, it has also been detected in the brains of creatures like fish and tadpoles.
Instead of individually studying all species across various hemlock forests, the research team is focusing on a single small amphibian as an indicator of the ecosystem. According to Christjansen, the eastern red-backed salamander is sensitive to both environmental changes and pollutants, making it a valuable bioindicator for assessing overall forest health.
To conduct the study, scientists placed coverboards in forests last year, creating habitats for salamanders. They monitored these coverboards periodically to count and observe the salamanders underneath, measuring and tagging them during the process. Some of the forests under investigation are treated with either or both insecticides, while others remain untreated.
The team also conducted behavioral tests on the salamanders, including gently prodding them to assess their response to predation and flipping them over to observe their recovery speed. Christjansen explained that the salamander’s population size, health status, and comparative size with those in untreated forests could provide insights into broader ecosystem impacts.
Julia Riley, an associate professor at Mount Allison University and a Canada Research Chair in integrative wildlife ecology, underscored the salamander’s significance as a forest health indicator due to their adaptability to environmental changes and their substantial presence in forest ecosystems.
The study is investigating the effects of dying hemlocks on the salamanders. Chris Edge, a supervisor and scientist with the Canadian Forest Service, emphasized that as hemlock trees perish due to HWA infestation, they degrade the unique habitat characteristics that make these forests suitable for wildlife.
Salamanders have delicate skin that relies on ample moisture, so any decrease in forest foliage due to dying hemlocks could impact salamander populations and behavior. The study involves collaboration between Mount Allison University, the Canadian Forest Service, Acadia University, Environment and Climate Change Canada, and the University of Saskatchewan, as part of a broader examination of forest health in Eastern Canada.
Christjansen indicated that the study will continue until the following year, with data collected during the summer set to be analyzed. The findings will be crucial in understanding the broader implications of HWA infestation and insecticide use on forest ecosystems.
In conclusion, the study sheds light on the complex relationship between an invasive pest, chemical control measures, and the delicate balance of wildlife in hemlock forests.