What’s on our hillsides?
Lower elevations of the south Okanagan Valley are covered by three types of plant associations: grass, sagebrush and forest. Each has its distinctiveness and appeal. This article focuses on two major trees: Douglas-fir and Ponderosa Pine.
Many people can’t tell one from the other but recognizing a tree as a Douglas-fir or a Ponderosa Pine is easy! The most obvious features that distinguish the two are the cones and the needles. Pine cones are stout, broadest at the base, almost as broad as they are long, and relatively large; an average pine cone would be 10 cms (5 inches) long and 8 cms (3 inches) broad. Pick up a cone, but do it carefully or you’ll drop it quickly because you’ll get stuck by the small prickles, one at the tip of each cone scale.
Douglas-fir cones are smaller (about 6 x 3 cms), cylindrical and lack prickles. Their most distinctive features are the large bracts, protruding well beyond the ends of the cone scales.
Looking at the needles, it is their length that distinguishes the pine from the Douglas-fir. Pine needles are about 20 cms (8 inches) long and Douglas-fir needles are short, up to 3 cms (1.3 inches). In addition pine needles are attached to the twig in a bundle of three, whereas Douglas-fir needles are not in bundles.
Old trees of both species can be magnificent. Because Ponderosa Pine and Douglas-fir are the major timber producing trees of western North America most of the big trees have been logged. But a few big trees remain in the Okanagan Valley like one in the Penticton area that is 4.9 m (16 feet) circumference and 38.7 m (127 feet) tall.
Some features of these trees are fascinating or unusual. One is the 2-years that it takes for the seeds of Ponderosa pine to ripen. Douglas-fir flowers in the spring and the seeds are mature in 3-4 months. But pine cones are not ripe the first autumn and continue to grow the next spring and summer, finally the seeds are released the second autumn after fertilization. On a hot day pine bark may give off a faint odor of vanilla. And pine bark flakes off in pieces shaped like those in a jigsaw puzzle.
Although trees may seem to be pretty solitary, a close look reveals a community of organisms inhabiting the tree. Recently squirrels in our neighborhood began gnawing the pine cones apart to eat the still green seeds. The diet of Clark’s Nutcrackers is almost entirely seeds of Ponderosa and Whitebark Pines. The Nutcrackers also cache seeds often in the soil at the base of clumps of grass. Many of these seeds are hunted-up later and eaten but some are overlooked and germinate thus spreading the pines about the countryside. Seeds are food for Pygmy Nuthatches, Mourning Doves, Quail and other birds. Red Crossbills have beaks modified so they can pry apart the cone scales and use their tongue to flick out the seeds. There are several populations of Red Crossbills. One population has beaks specialized to extract seeds from pines, in another the beak is adapted to feed on spruce seeds and so on.
A variety of insects live in the pines. In late July adult Pine White butterflies appear and make their distinctive short, slow, convoluted flight around the tops of large Ponderosa Pines. Eggs are laid at the base of needles where they overwinter. The following spring the caterpillars emerge from the eggs and feed on the relatively succulent new needles. Tiny (3-4 mm long) Western Pine Beetles are responsible for many patches of dead Ponderosa Pines on the hillsides. The beetles tunnel under pine bark, depositing spores of a Blue-stain Fungus as they go. Disruption of water flow from the roots to the needles by the beetles and fungus is sufficient to kill the tree. Here three major groups of organisms (plants, insects and fungi) are interacting. The complexity of such relationships illustrate the power of Nature.
Ponderosa Pine and Douglas-fir are adapted to the climate, soils and moisture of the South Okanagan. Whether big or small they are beautiful trees and they should be used more often in large landscape projects, if for no other reason than they require less watering than exotic trees like maples, cedars and spruces.
The South Okanagan Naturalists’ Club’s next meeting is September 23 in the United Church, 696 Main St., Penticton at 7:30 pm. Dr. George Scotter, renowned author, botanist, and parks planner, will talk on NAHANNI – PAST, PRESENT, FUTURE. The Nahanni National Park Reserve in northern Canada is now nearly seven times the size of the original established in 1972. It permanently protects over 30,000 square Km of Boreal wilderness, an area the size of Vancouver Island. The Nahanni is now one of the world’s greatest protected areas, taking its place alongside Banff and Jasper. How did this all happen? Come and hear Dr. Scotter tell about the history of this spectacularly beautiful landscape and how it became a park. He was a member of the original team that studied the area for its national park potential. All are welcome.For details contact Glenda at 250-462-7500.