Seed Viability and Female Cone Characteristics of Mature Knobcone Pine Trees

As humans continue to alter ecosystems through land-use activities, revegetation projects will be one important way to restore or maintain impacted plant communities. Certain species, such as knobcone pine (Pinus attenuata Lemmon), have been used in some revegetation projects because of their preferable traits. Information on seed production and viability is critical to planning effective projects but is often limited for noncommercial conifer species. Here, we report on cone characteristics, seed quality, and germination rate from female cones collected in mature (63–71 years old) knobcone pine forests, northern Coast Range, California. Cones were divided into two age groups: brown (1–2 years old) and gray (3 years old). Gray cones were longer and had more unfilled seeds (40%) compared to the brown cones (23%). The number of seeds per cone depended on the extraction method, ranging from 93 to 95 seeds for brown cones and 61 to 96 seeds for gray cones. Germination rate for all seeds combined was approximately 80%. Although there are reports of old, serotinous knobcone pine cones containing viable seeds, it is unclear whether mature stands are important seed collection sources. Stands sampled in this work are still producing a viable canopy seed bank. As restoration projects trend toward using native species, information on the potential use of available seed bank and its viability is critical for planning.