Nevins
Research
FOCAL TREE SPECIES
DRIVERS OF VARIATION IN TREE RESPONSES TO DROUGHT
Tree mortality from drought and many other compounding biotic and abiotic factors is increasing across the globe. In the northwestern US, more frequent and severe droughts are expected in the coming decades.
Understanding how forest communities are going to respond to drought and change in the future will be essential for effective predictions of changes to forest functioning, and management applications.
The central goal of my research is to investigate the drivers of variation in how tree species in the NW US respond to drought.
Top Right: Old growth Douglas Fir and Port Orford Cedar grove in the Six Rivers National Forest in northern California. Bottom Left: Forest in the Siskiyou National Forest in southern Oregon after a fire and severe drought.
TREE-MYCORRHIZAL FUNGAL ASSOCIATIONS AND FUNCTIONAL TRAITS
Mycorrhizal fungi associate with more than 90% of terrestrial vascular plants on Earth, in an intimate symbiosis that can confer important benefits to the host plant. These associations can improve tree resistance and resilience to drought by improving nutrient acquisition and water uptake. Tree traits, such as root architecture, are also fundamentally tied to these important functions, and are thought to vary in response to their mycorrhizal associations.
Combined, tree traits and mycorrhizal associations play an essential role in drought responses, tree demography, and the capacity of forests to perform important ecosystem services like supporting biodiversity and sequestering carbon. My work thus far has characterized the mycorrhizal fungal communities associating with my ten host tree species in sites from northern Washington to northern California. I have also sampled tree leaf and root traits at one old growth forest site, and am currently working to evaluate how mycorrhizal functions and host tree traits vary, and how this impacts tree survival and growth.
My central questions are:
1. How does drought and soil nutrient variation drive the community composition of tree-associated mycorrhizal fungi in the NW US?
2. Are the distributions of mycorrhizal functions and tree traits in an old growth forest community driven by the same or different processes?
3. Can assessing patterns of tree trait variation and mycorrhizal associations help us understand variation in tree survival and growth rates?
Upper Right: Ectomycorrhizal hartig net on roots of Tsuga heterophylla in southwest OR. Bottom: 1) Foliage of Abies procera in central OR; 2) Root sample of Cornus nuttallii in northwest CA; 3) Fungal mycelium in rhizosphere of Pinus monticola in northwest CA; 4) Fungal mycelium in rhizosphere of Abies amabilis in central OR.