table isotope analysis is a powerful tool for assessing plant carbon and water relations and their impact on biogeochemical processes at different scales. Our process-based understanding of stable isotope signals, as well as technological developments, has progressed significantly, opening new frontiers in ecological and interdisciplinary research. This has promoted the...
Dwarf mistletoes, obligate, parasitic plants with diminutive aerial shoots, have long-term effects on host tree water relations, hydraulic architecture, and photosynthetic gas exchange and can eventually lead to tree death. To investigate the long-term impacts of dwarf mistletoe on gas exchange of host western hemlock trees, I compared growth, gas...
The Penman‐Monteith equation is often used to estimate transpiration, but an important limitation to this approach, especially for mountainous forested sites, is an accurate estimate of canopy conductance averaged over the area of interest (Gs). We propose a method for estimating watershed‐scale transpiration using estimates of Gs derived from measurements...
This thesis consists of three manuscripts describing ecophysiological research on the cyanolichen Lobaria oregana. The first manuscript includes a re-evaluation of the assumptions underlying past estimates of N fixation by this species and provides an estimate of annual N fixation at the Wind River Canopy Crane (WRCC). Based upon litterfall...
Molybdenum is an essential component of biogeochemical cycling, most notably as a component of the nitrogenase enzyme used in biological nitrogen (N) fixation. While the important role of phosphorus (P) in limiting N fixation in ecosystems has been well documented, occurrence and prevalence of molybdenum (Mo) limitation is largely unknown....
The epiphytic lichen Letharia vulpina has been commonly sampled in-situ for nitrogen (N) deposition biomonitoring studies but has never before been transplanted for this purpose. In the high-elevation wilderness areas of southern California Letharia vulpina is generally uncommon, making in-situ sampling difficult. In this study, we compared thallus N accumulation...
In the mountains of central and southern California, high elevation wilderness areas lack epiphytic lichens that can be used to inform us about atmospheric deposition in multiple ways. Epiphytic lichens are capable of accumulating elements proportionally to the local atmospheric concentration, establishing them as commonly used biomonitor of key elements....
Buddleja davidii (butterfly bush) is a highly adaptable landscape plant known for pollinator attraction. Unfortunately, it is also regarded as an invasive plant in highly disturbed environments across the globe. It is an invasive species in Oregon, officially classified as a class B noxious weed in 2004. Currently the state...
Vietnam is considered one of the most climate change-vulnerable countries due to its high dependence on agriculture and its coastal location. Increased atmospheric temperatures caused by climate change also significantly threaten one of Vietnam's most important cash crops, robusta coffee (Coffea canephora). Suitable cultivation sites of robusta, which comprises 97%...
Lichens play many important roles in subarctic terrestrial ecosystems by fixing nitrogen, colonizing rock and gravel, stabilizing otherwise bare soil, adding significantly to vegetation biodiversity and serving as the primary food for caribou in the winter. In these chapters, I analyzed lichen community and ecological trait structure along environmental gradients,...