Estimating seed crops of conifer and hardwood species

Abstract

Cone, acorn, and berry crops of ponderosa pine (Pinusponderosa Dougl. ex Laws. var. ponderosa), sugar pine (Pinuslambertiana Dougl.), Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), California white fir (Abiesconcolor var. lowiana (Gord.) Lemm.), incense-cedar (Libocedrusdecurrens Torr.), California black oak (Quercuskelloggii Newb.), tan oak (Lithocarpusdensiflorus (Hook. & Arn.) Rehd.), and Pacific madrone (Arbutusmenziesii Pursh) were evaluated over a 24-year period (1958–1981) from an area in northern California by an easy to use visual crop rating system. Seed-trap data, also for 24 years, were gathered for four conifer species. Together, these data provide the wild-land manager with knowledge on seed-crop quantity, quality, and timing. The visual rating system involves visually estimating the amount of fruit in trees and the proportion of trees with fruit, and ranking the crop by species. Regressions of sound seed and total seed on seed-crop rating are provided for the two species with the most seed crops: ponderosa pine and Douglas-fir. Regressions were significant at the 1% level, and coefficients of determination ranged from 0.58 to 0.76.