Professor Stephen C. Sillett

Current research

Save the Redwoods League’s Redwood Climate Change Initiative (Phase 2)—Sixteen 1-hectare plots in old-growth forests of Sequoia sempervirens and Sequoiadendron giganteum are being re-measured 5 years after plot installations to quantify rates of aboveground growth and carbon sequestration. Additional plots and individual trees throughout the geographic ranges of the species are also being measured.

Dendrochronology—Tree-ring samples collected during routine measurements are crossdated and curated by Allyson L. Carroll ( We use these samples to quantify tree ages, rates of productivity, and dendroclimatic relationships. Please contact Allyson via email with inquiries about this work.

Structural development of old-growth Douglas-fir rainforests—Four 1-hectare plots in Pseudotsuga menziesii forests of the western Olympic Mountains, Washington are being established to quantify aboveground biomass, rates of productivity, and arboreal biodiversity.

Biodiversity of old-growth redwood forest canopy—One 1-hectare plot and additional trees in Redwood Experimental Forest are being monitored for arboreal wildlife (diversity, behavior) and canopy microclimates (light, wind, temperature, humidity, soil moisture).

Allometric equations for the six tallest tree species—Having completed equations for Sequoia sempervirens, Sequoiadendron giganteum, and Eucalyptus regnans, work on the remaining 3 species (Pseudotsuga menziesii, Picea sitchensis, and Eucalyptus globulus) is underway.

Manipulating tree crown structure to accelerate development of old-growth characteristics in second-growth redwood forests—Twenty-four trees in six locations have been manipulated via a factorial experiment involving topping, pruning, and branch tipping to determine if trunk reiteration and limb development can be initiated in a time frame meaningful for management. If so, it may be possible to entice old-growth dependent species such as the marbled murrelet (Brachyramphus marmoratus) to colonize second-growth forests in the not-too-distant future.