The Douglas-fir Seed-Source Movement Trial, initiated in 2009 across multiple sites in Oregon and Washington, is now yielding important results. Measurements of some variables, such as cold hardiness, follow the same pattern across sites, giving scientists confidence in predicting future responses in populations of Douglas-fir and in developing seed-transfer guidelines. But the presence of less-consistent results across sites for other variables, such as drought hardiness, show the value of having multiple sites across a range of climate and soil conditions. Responses of needle cast diseases also demonstrate a strong relationship with seed-source environment. Moving sources from dry environments to ones which are substantially wetter increases the risk of symptoms associated with needle casts.
Many land managers have begun discussing potential future changes in plant responses with climate change and are discussing study results with upper management or advisory boards.