Nevins
Research
FOCAL TREE SPECIES
DRIVERS OF TREE DEMOGRAPHY IN RESPONSE TO CHANGING ENVIRONMENTS AND SHIFTING DISTURBANCE REGIMES
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 other environmental stress and disturbance 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 tree demography in the NW US, by integrating both above- and belowground perspectives to understand tree responses to environmental variation and disturbance.
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 TRAIT-BASED APPROACHES
Mycorrhizal fungi associate with more than 90% of terrestrial vascular plants on Earth, and are fundamental to nutrient cycling, carbon storage, and plant productivity across diverse ecosystems. Symbiotic associations with mycorrhizal fungi can improve tree resistance and resilience to drought and other stressors by improving nutrient acquisition and water uptake. Tree traits, such as root architecture, are also fundamentally tied to these important functions, and have been documented 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 has characterized the taxonomic and functional composition of mycorrhizal fungal communities associating with tree species in sites from northern Washington to northern California. I have also measured tree leaf and root traits at one old growth forest site, and have evaluated how mycorrhizal functions and host tree traits vary, and how this impacts tree growth.
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.