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Genetics Project
Geographic Variation in Longleaf Pine: Improving Deployment of Seed Source to Site (Dr. Lisa Samuelson and Tom Stokes)
Studies of geographic variation in longleaf pine are relatively few compared to the other southern pines and breeding programs have focused primarily on survival, initial height growth and resistance to brown-spot needle blight (for example, the Western Gulf Forest Tree Improvement Program). Research by Wells and Wakeley in the 1970s from the Southwide Southern Pine Seed Source Study demonstrated that significant geographic variation in survival, initiation of height growth, growth characteristics, and disease resistance exists in longleaf pine and limited provenance testing indicates that local seed sources may not always be the best. Work by Schmidtling and colleagues determined that in general, growth was related to latitude and minimum temperature with seed sources from warmer climates exhibiting faster growth when grown in a warm climate than sources from cooler climates. Other early studies summarized by Dorman in 1976 indicated geographic variation in the number of fibrous roots, timing of flowering, specific gravity and frost tolerance. In addition, longleaf from west of the Mississippi River has been reported to be more susceptible to brown-spot needle blight than sources east of the river.
A wider geographic range in longleaf seed sources is now available for planting, including montane sources. Given the substantial effort underway to restore longleaf pine throughout its native range, more information on site adaptability and the subsequent need for deployment of specific sources to different sites to increase survivability and growth is needed. Juvenile and mature longleaf pine have been shown to be sensitive to drought and over the next 25 to 50 years, temperatures and the frequency of extreme weather events in the southeastern U.S. are predicted to increase. These conditions combined with high runoff may reduce the amount of moisture captured and available for tree growth. Therefore, information on variability in adaptability of different seed sources to drought is also needed to match seed source to site and ensure long-term success of restoration plantings.
We are collecting preliminary data on seedling variation in drought tolerance, physiological processes, biomass allocation, growth and disease resistance in nine longleaf seed sources generously provided by the International Forest Company. This study will identify important variables to examine in out-planting studies in addition to standard attributes such as survival, duration of grass stage and brown-spot resistance. We are seeking support to implement field trials using different seed sources planted in replicated studies in as many sites and states as funding permits. Please contact Lisa Samuelson if you are interested in supporting this new endeavor to improve longleaf pine restoration!
