Tree-of-heaven is an invasive, nonnative species that invades newly disturbed areas and forms large monospecific stands. It was surveyed from a vehicle along 5,175 km of roads in Virginia in 2004, 2005, 2010, and 2011. Fifty-eight percent of every 1.6-km road segment had at least one tree-of-heaven. Mean density of tree-of-heaven throughout the roads surveyed in Virginia was 39 km−1. The interaction between road classification (interstate, primary, and secondary) and physiographic region (mountain, piedmont, and tidewater) was significant; consequently, the density of tree-of-heaven along the different road classifications depended on the effect of the physiographic region and vice versa. Tree-of-heaven was fairly evenly distributed throughout Virginia ranging from 39 to 78% of 1.6-km road segments infested, but had a greater variation in density. Current areas with low densities could increase in density in the future. The highest density of tree-of-heaven was along interstate highways in the mountains (85 km−1), followed by the tidewater (63 km−1), and piedmont (46 km−1) regions. Primary roads had a moderate density of tree-of-heaven with a range of 24 to 36 km−1. Secondary roads had lower densities with 12 km−1 and 41 km−1 in the tidewater and mountain regions, respectively. Tree-of-heaven spreads primarily by wind-dispersed seeds from female trees, and populations bordering roadsides could serve as seed sources for further local and landscape spread.

Wapusk National Park is part of the Hudson Bay Lowlands in Manitoba and covers 11 475 km2. Lichen surveys were initiated in 2002 but none have reported all species incorporating broad habitat types or a baseline on which to make management decisions. The objectives of this study were: 1) to determine species diversity, including species richness and evenness of the lichens present; 2) to explore species distributions; and 3) to compare lichen growth form and substratum relationships among physiographic regions. Fifty-six locations in four habitat types (physiographic regions: open coastal beach ridge, forested coastal beach ridge, boreal transition forest, and peat plateau bog) and three burned locations were visited over nine years and specimens were collected at each location. A total of 276 species and subspecies were collected. One species is new to Canada (Buellia uberior Anzi) and ten species are new to Manitoba. Species diversity, evenness, and richness were highest in the coastal beach ridge. The open coastal beach ridge, boreal transition forest, and peat plateau bogs formed separate clusters in the non-metric multidimensional scaling (NMS) but the forested coastal beach ridge overlapped with the open coastal beach ridge. Unique species in each region may serve as indicators to monitor long-term changes. While the coastal beach ridge facilitates travel along the coast, it also represents the region with the highest need for intervention to conserve species diversity.