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    Author(s): Josh McDaniel; Janet S. Prevey; Connie HarringtonBrad St. Clair
    Date: 2019
    Source: Science Findings 216. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 5 p.
    Publication Series: Science Findings
    Station: Pacific Northwest Research Station
    PDF: Download Publication  (4.0 MB)


    To successfully reproduce, conifers must have impeccable timing—opening their female cones to receive pollen from the male cones of nearby trees. This timing is a response to temperature and other environmental cues. It is to the tree’s advantage to flower when risk of damaging frost is low, but early enough in the spring to take full advantage of the growing season.

    Douglas-fir is ecologically important and the cornerstone of the timber industry in the Pacific Northwest. Seed orchard managers carefully breed different populations of the species to produce seedlings that will thrive in particular areas in need of replanting. Understanding the environmental cues that influence the timing of flowering is important for predicting how reproduction and survival of trees will change in the future. To address this need, a team of researchers with the USDA Forest Service Pacific Northwest Research Station developed a model that predicts, within an average of 5 days, when Douglas-fir will flower. Seed orchard managers are using the model to plan and schedule time-sensitive tasks related to flowering in the orchards.

    The model highlights how both cool and warm temperatures influence the date of flowering for Douglas-fir. It can be used to predict how future changes in temperature could influence flowering times across the range of Douglas-fir under different climate predictions.

    Publication Notes

    • Visit PNW's Publication Request Page to request a hard copy of this publication.
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    McDaniel, Josh; Prevey, Janet S.; Harrington, Connie; St. Clair, Brad. 2019. Nature and Nurture: Genetics and Climate Influence the Timing of Flowering in Trees. Science Findings 216. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 5 p.


    Douglas-fir, phenology, climate change, reproductive budburst.

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