Graduation Date

Fall 2016

Document Type

Dissertation/Thesis

Program

Master of Science degree with a major in Natural Resources, option Forestry, Watershed, & Wildland Sciences

Committee Chair Name

John-Pascal Berrill

Committee Chair Email

john-pascal.berrill@humboldt.edu

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Christa M. Dagley

Second Committee Member Email

christa.dagley@humboldt.edu

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Erik S. Jules

Third Committee Member Email

erik.jules@humboldt.edu

Third Committee Member Affiliation

HSU Faculty or Staff

Abstract

In its current fragmented distribution in 75 groves along the western slope of the Sierra Nevada, Sequoiadendron giganteum (SEGI) may be vulnerable to extreme shifts in environmental conditions such as warming temperatures and drought stress, which may reduce the already limited habitat for SEGI in native groves. Interest in outplanting of this iconic species for the objectives of genetic conservation and timber utilization due to decay resistance of heartwood would be supported by information on population variation to inform seed collection for these plantings. To that end, I assessed three SEGI common-garden trials which had been planted in spring 1981 at the USDA Forest Service Foresthill Seed Orchard (FSO), north of the current species range and at lower elevation, in summer 2009. My analysis of genetic variances and geographic patterns of variation among populations of SEGI stecklings (rooted cuttings) from a 23 grove sample (trial 1 and 2) revealed higher than expected genetic variances for tree size and form traits. Genetic variance of heartwood decay was low. The area of SEGI native grove origin and the extent of grove isolation were the strongest predictors of tree size at FSO, with the grove samples originating from larger and less isolated native groves growing best. Accounting for the effect of grove area, SEGI grove samples originating from higher elevation native groves with a history of past harvesting were largest by height. In mixed species plantings of SEGI seedlings and five mixed conifer species co-occurring in SEGI’s native range (trial 2 and 3) several mixed conifer species, including Pinus ponderosa (PIPO) and Pinus lambertiana (PILA) outgrew the SEGI seedlings. In plantings outside of SEGI’s native range, SEGI may be outcompeted by mixed conifers such as PIPO, particularly on dry sites at lower elevations.

Citation Style

Society of American Foresters

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