Shrubs are important for grasslands; however, shrub encroachment has threatened the integrity of grasslands worldwide. Understanding shrub extent and local effects on encroachment can prioritize management. Studies that map low stature shrubs using an object-based approach in large areas of northern grasslands are limited. This study i) locates shrubs with an object-based approach using 30 cm colour-infrared aerial imagery and Support Vector Machine classification; and ii) investigates shrub distribution by topo-edaphic factors in the native fescue grasslands of the West Block in Cypress Hills Interprovincial Park, Saskatchewan, Canada. The overall accuracy of detected shrubs was above 92%. Loam flat regions, North-facing slopes, and areas with 0% to 25% slope rise are connected to high shrub cover and relate to soil moisture. Shrub presence is high closer to watercourse lines and waterbodies, and low closer to wetlands. This research can apply to other shrub encroached areas to facilitate shrub management worldwide.

Changes to historic fire and grazing regimes have been associated with the expansion of tree cover at forest–grassland boundaries. We evaluated forest expansion across a mosaic landscape in western Canada using aerial photos, airborne laser scanning, and field transects. The annual rate of forest expansion (0.12%) was on the low end of rates documented across North America and was greater from the 1970s to the 1990s than from the 1990s to 2018. Most forest expansion occurred within 50 m of established forests, and 68% of all tree regeneration in grasslands was within 15 m of the forest edge. The intensity of cattle grazing did not affect the tree regeneration density. Despite the slow pace of land cover change, grassland areas near the forest edge had an average of 20% canopy cover and 9 m canopy height, indicating the presence of tall but sporadic trees. The rate of forest expansion, density of tree regeneration, and tree cover within grasslands were all greater at lower elevations where trembling aspen (Populus tremuloides) and white spruce (Picea glauca) were the dominant tree species. We conclude that proportions of forest–grassland cover on this landscape are not expected to change dramatically in the absence of major fire over the next several decades.

Spongy moth (Lymantria dispar dispar) has caused considerable damage to oak trees across eastern deciduous forests. Forest management, post-outbreak, is resource intensive and typically focused on ecosystem restoration or resource loss mitigation. Some local forest managers and government partners are exploring developing technologies such as Unpiloted Aerial Systems (UASs, UAVs, or drones) to enhance their ability to gather reliable fine-scale information. However, with limited resources and the complexity of investing in hardware, software, and technical expertise, the decision to adopt UAS technologies has raised questions on their effectiveness. The objective of this study was to evaluate the abilities of two UAS surveying approaches for classifying the health of individual oak trees following a spongy moth outbreak. Combinations of two UAS multispectral sensors and two Structure from Motion (SfM)-based software are compared. The results indicate that the overall classification accuracy differed by as much as 3.8% between the hardware and software configurations. Additionally, the class-specific accuracy for ’Declining Oaks‘ differed by 5–10% (producer’s and user’s accuracies). The processing experience between open-source and commercial SfM software was also documented and demonstrated a 25-to-75-fold increase in processing duration. These results point out major considerations of time and software accessibility when selecting between hardware and software options for fine-scale forest mapping. Based on these findings, future stakeholders can decide between cost, practicality, technical complexity, and effectiveness.