Coast redwood planted outside its range outperforms the native Douglas-fir beneath an overstory of varying density

Restoration of conifer dominance and structural complexity in second-growth forests of northern California is a key management objective following historic logging and fire exclusion. We evaluated the performance of coast redwood ( Sequoia sempervirens ) and coast Douglas-fir ( Pseudotsuga menziesii var. menziesii ) nursery stock 8 years after planting following a retention harvest designed to enhance fine-scale heterogeneity in the spatial pattern of overstory tree retention. The study was conducted just outside redwood’s range in Humboldt County, north coastal California. Redwood exhibited higher survivorship over 8 years since planting, and had the same average height as Douglas-fir after 8 years, growing more rapidly and catching up in height over the last 2 years. Douglas-fir mortality was greater in areas of higher overstory retention. Canopy openness and soil relative water content were the strongest predictors of height and recent height increment. These early findings indicate that redwood can establish and perform competitively outside its natural range under the retention system, supporting potential expansion of its use in timber production and for other objectives such as wildfire resilience, carbon sequestration, structural complexity, and biodiversity enhancement. Continued monitoring will be essential to determine how varying retention levels and soil moisture dynamics influence the long-term development of planted conifers under a spatially-heterogeneous canopy.