Publication Date

Fall 2012

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Studies

Advisor

William Russell

Keywords

Canopy ecology, Mendocino County, old-growth forests, Pygmy, Sequoia sempervirens, Spodosol soils

Subject Areas

Ecology; Environmental studies

Abstract

The tallest tree in the world is the coast redwood, Sequoia sempervirens, a species endemic to a 16-km-wide coastal belt extending from Big Sur, California, to southern Oregon. Old-growth redwood forests are home to other plant and animal species that depend on structural characteristics that have formed over hundreds of years. While a great deal of research regarding growth form and structure has taken place on highly productive stands, little work has been done on marginal sites, where redwoods are on the edge of their ecological tolerance. In the Northern California County of Mendocino, hydrophobic spodosol are host to endemic and adapted species called "pygmy." Such species include the rare bolander pine (Pinus contorta spp. bolanderi), pygmy cypress (Cupressus pygmaea), and a number of Ericaceous shrubs. However, the coast redwood has also been observed growing in this soil type.

Using previous soil and vegetation characterizations across the ecotone of the pygmy forest, this study focused on the structural characteristics of Sequoia sempervirens in a stunted stand of old-growth coast redwood in Mendocino County, California. Stepwise linear regression analysis showed total tree height and size to be correlated with soil nutrient levels as expected, but the number of epiphytes in the canopy of pygmy coast redwoods was not correlated with canopy complexity as expected. Instead, epiphyte abundance was significantly correlated with fire hollow volumes, suggesting fire to be a factor in canopy plant communities.

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