Skip to main content

Catherine A Gehring

• Theoretical and empirical research has supported the hypothesis that plant–plant interactions change from competition to facilitation with increasing abiotic stress. However, the consistency of such changes has been questioned in arid and semiarid ecosystems. • During a drought in the semiarid south-western USA, we used observations and a field experiment to examine the interactions between juveniles of a foundation tree (Pinyon pine, Pinus edulis ) and a common shrub (Apache plume, Fallugia paradoxa ) in replicated areas of high and low stress. • The presence of F. paradoxa reduced P. edulis performance at low-stress sites, but had the opposite effect at high-stress sites. However, the intensity of the...
1 Recent research has demonstrated important linkages between above- and below-ground components of terrestrial ecosystems, but the relationships between aerial parasitic plants, such as dwarf mistletoes, and below-ground organisms, such as mycorrhizal fungi, have not been examined in detail. 2 We examined the relationship between dwarf mistletoe infection, host vigour and the ectomycorrhizal colonization and fungal community composition of pinyon pine (Pinus edulis) using a combination of field observations and glasshouse studies. 3 High levels of dwarf mistletoe infection were not associated with increased mortality or needle loss of infected pinyons, but infected trees had lower shoot growth. 4 Ectomycorrhizal...
Forest management, climatic change, and atmospheric N deposition can affect soil biogeochemistry, but their combined effects are not well understood. We examined the effects of water and N amendments and forest thinning and burning on soil N pools and fluxes in ponderosa pine forests near Flagstaff, Arizona (USA). Using a 15N-depleted fertilizer, we also documented the distribution of added N into soil N pools. Because thinning and burning can increase soil water content and N availability, we hypothesized that these changes would alleviate water and N limitation of soil processes, causing smaller responses to added N and water in the restored stand. We found little support for this hypothesis. Responses of fine...
ScienceBase brings together the best information it can find about USGS researchers and offices to show connections to publications, projects, and data. We are still working to improve this process and information is by no means complete. If you don't see everything you know is associated with you, a colleague, or your office, please be patient while we work to connect the dots. Feel free to contact sciencebase@usgs.gov.