Thickets of willow shrubs constitute biodiversity hotspots in low-arctic tundra. Shrubs thickets are expected to expand under climate warming, but expansion of efficient boreal herbivores into the tundra may counteract shrub encroachment. In northeast Norway, the outbreaking winter moth has expanded its range through the northern-boreal birch forest until reaching the edge of the low-arctic tundra on the Varanger Peninsula. In 2017 and 2018, we received reports of intensified moth outbreaks on willow thickets well beyond the birch treeline in this area. The local public and authorities expressed great concern over this development, and there was high demand for knowledge about the current extent and likely future development of these outbreaks. At present, however, poor knowledge about the suitability of willow as a host for the winter moth prevents us from telling if outbreaks on willow simply represent a “spillover” of larvae from birch, or if the winter moth will be capable of displaying outbreaks also in pure willow shrub tundra well beyond the arctic birch treeline. The project “Pioneering Pests” constitutes a series of pilot studies that will fill the most pressing knowledge gaps and test methods for monitoring moth outbreaks on willow. Specifically, we will test if the winter moth can complete its lifecycle on willow, if willow outbreaks require the presence of birch in thickets, if willow is a phenologically favorable host for the winter moth, and how outbreaks are distributed along a gradient running from the edge of the birch forest and into the tundra.
UiT Norges arktiske universitet
Project manager: Ole Petter Laksformso Vindstad
Project code: 352018