Seed supply is a key feature of tree population dynamics, and seed production may be indicative of environmental and biological drivers. This study examines cone production in upper-slope, true fir-hemlock forests of the Pacific Northwest, starting in 1959 to the present. Annual surveys of cone counts of Abies spp. (A. amabilis, A. concolor, A. grandis, A. lasiocarpa, A. magnifica, A. procera), Pinus spp. (P. engelmannii, P. lamberti, P. monticola), and Tsuga spp. (T mertsiana) have been conducted at sixty-one plots in 37 locations in nine national forests in Washington and Oregon (originally 10 national forests, but Mt. Baker and Snoqualimie were combined). At each site, a visual count is made of cone production in each of a number (20-30) trees in a stand of one tree species. At some plots, additional trees were added in the 1980s. Primary data include numbers of counts per tree per year, periodic measurements of tree diameter, and the names of the sites. These data illustrate the periodicity of cone production cycles, as well as longer trends associated with climate change and variability in the region.
Greg M Cohn, Jerry F. Franklin, John Moreau, Joseph E. Means, Julia A. Jones, Mark D Schulze
The original goal was to document the sizes of annual cone crops of upper slope conifer species to facilitate planning seed collection efforts and to elucidate this portion of these species life cycles. New goals are: to examine the spatial and temporal patterns of cone production in these species, to examine their relationships with weather patterns, and to provide an essential database to examine the potential impacts of climate change on cone production.