UC Berkeley

Coast redwood (Sequoia sempervirens (D. Don) Endl.) is a valuable endemic and

important source of timber and carbon storage in California. This species is unique among

conifers in its ability to reproduce clonally through prolific sprouting. Due to extensive

timber harvesting, only ~5% of the native range of old growth redwood forest remains

uncut. Knowledge about clonal diversity and patterns throughout the range of coast

redwood may allow us to better understand the reproductive ecology of this species and

identify populations that may be at risk due to low genetic or genotypic diversity. In this

dissertation, clonal diversity and patterns are described in two paired one-hectare plots at

each of three old-growth redwood forests located at different latitudes within the native the

range of coast redwood. The impacts of clonal reproduction on spatial patterns in old

redwood forests are also explored. High levels of genetic and genotypic diversity were

present at all three study sites. Clonal diversity and structure did not seem due vary by

geographic location. Instead, variation between study plots may have been due to a

combination of local environmental factors and disturbance history. Clones were spatially

aggregated at all study plots, and clonal reproduction generally led to significant spatial

clustering at scales less than 10 m. The finding of high genotypic diversity suggests that

despite prolific sprouting, sexual recruitment still plays an important role in the reproductive

ecology of coast redwood. In order to emulate old forest reference conditions, second

growth forests should be managed to maintain high levels of clonal diversity. Additionally,

forest managers seeking to restore old forest characteristics should plant and thin to create

spatial patterns that mix single seed-origin trees and clonal clusters.