Trees at Stanford is an incredible project which maps the tree species on Stanford's Campus in California. Their website documents over 400 species! Stanford has employed botanists as faculty for over a hundred years, so this online-resource is very robust. The campus is home to many native species, particularly oaks. A great resource for amateur and expert botanists alike.
The site also links to tree walks in nearby areas created by the organization Canopy (https://canopy.org/our-work/tree-walks/), including one in my neighborhood!
https://trees.stanford.edu/
Researchers were interested in seeing the impact of traffic on nitrogen levels in a mixed-coniferous forest in my home state of California. With the rise of development and vehicles, they wanted to know how ecosystems have been changed. Their study focused on the Sierra Nevada region along Interstate-80 (high traffic) and Henness Pass Road (low traffic) where they collected lichen (L. vulpina ) samples along transects. Lichen was chosen because it is sensitive to environmental change and can uptake particles such as nitrogen. Samples were then dried and analyzed for N and C isotopes and trace-element values were found using inductively coupled plasma–mass spectrometry. Researchers found significantly higher N values near the high traffic road, where %N was negatively correlated from distance from the road. Zn and As were also higher around I-80. Nearby tree species did not significantly impact lichen cover. Lichen proved to be useful in showing differences between high and low traffic areas and could be used as a bioindicator in future research.
Bermejo-Orduna, R., McBride, J. R., Shiraishi, K., Elustondo, D., Lasheras, E., & Santamaría, J. M. (2014). Biomonitoring of traffic-related nitrogen pollution using Letharia vulpina (L.) Hue in the Sierra Nevada, California. Science of the total environment, 490, 205-212.
https://doi.org/10.1016/j.scitotenv.2014.04.119
