Growth
Rocky Mountain Douglas-fir grows more slowly than coast Douglas-fir and is also much more cold tolerant. Tolerance of different environmental conditions varies among populations of Rocky Mountain Douglas-fir, especially among populations from the northern and southern Rockies. However, even nearby populations can differ in cold hardiness.
Root morphology is variable, but when unimpeded, a taproot forms within several years. "Platelike" root morphologies occur where growth is impeded. The most prominent lateral roots begin in the 1st or 2nd year of growth. Most roots in surface soil are "long ropelike laterals of secondary and tertiary origin". Fine-root production is episodic in response to changing environmental conditions; the average lifespan of fine roots is usually between several days and several weeks.
Rocky Mountain Douglas-fir reaches reproductive maturity at 12–15 years. It has winged seeds that are dispersed primarily by wind and gravity. In western Montana clearcuts, seeds were dispersed up to 250 m (800 feet) uphill from their source, but seedfall between 180–250 m (600–800 feet) was only 7% of that found in uncut stands. Other studies determined that seedfall in clearcuts beyond 80 m (265 feet) from seed trees was about 3% of seedfall in uncut stands where seed trees are close together. Well-stocked stands have resulted from seedfall from sources 1–2 km (0.6–1.2 miles) distant, but most Douglas-fir seeds fall within 100 m (330 feet) of their source. Small amounts of seed are dispersed by mice, chipmunks, and squirrels. Rocky Mountain Douglas-fir seeds are disseminated about twice as far as seeds of Ponderosa pine.
Read more about this topic: Pseudotsuga Menziesii Var. glauca
Famous quotes containing the word growth:
“Those who have been immersed in the tragedy of massive death during wartime, and who have faced it squarely, never allowing their senses and feelings to become numbed and indifferent, have emerged from their experiences with growth and humanness greater than that achieved through almost any other means.”
—Elisabeth Kübler-Ross (b. 1926)
“Rights! There are no rights whatever without corresponding duties. Look at the history of the growth of our constitution, and you will see that our ancestors never upon any occasion stated, as a ground for claiming any of their privileges, an abstract right inherent in themselves; you will nowhere in our parliamentary records find the miserable sophism of the Rights of Man.”
—Samuel Taylor Coleridge (1772–1834)
“This [new] period of parenting is an intense one. Never will we know such responsibility, such productive and hard work, such potential for isolation in the caretaking role and such intimacy and close involvement in the growth and development of another human being.”
—Joan Sheingold Ditzion and Dennie Palmer (20th century)