In The Garden: September 2018

Have you read “Tree: A Life Story?” by David Suzuki and Wayne Grady? If not, this prize-winning book is available through our library, and Greystone Books has just released a second edition. This small book, lovingly illustrated by Robert Bateman, traces the life of one native Douglas fir tree from its beginning hundreds of years ago to its recent demise and service as a forest nurse log.

This book enhances your appreciation of the web of life that characterizes our Point Roberts ecology. Looking at aerial photographs, one easily sees that our trees and forests distinguish us from Delta, which has only remnants of forests outside of Burns Bog. However, steadily but surely, we are losing our tree canopy, most immediately due to tree removal and more gradually to climate change. There are many reasons to slow down this loss.

First, mature trees are magnificent garden features. Douglas firs and western red cedars form the year-long green backdrop and sometimes even the core of our gardens. That certainly is the case in my neighborhood, with virtually every garden either revolving around a mature tree or separated from other properties by magnificent giants. A few gardeners elsewhere might gaze on a tall western hemlock or grand fir, although it is my impression that both are now largely confined to densely forested areas away from gardens.

It might surprise you that, with very few scattered ancient trees, our Point Roberts forests are secondary rather than old-growth forests. Fire and logging to clear farmland or space for houses and septic systems have taken their toll on our original forest. It has taken almost 100 years to regenerate much of our canopy. But now, when one looks at Point Roberts from the air or approaches it from Highway 17, what one sees are tall, dark, magnificent evergreens. Think of what Point Roberts would look like if it were clear-cut. I can’t really speak to your particular garden, but the gardens in my neighborhood would look suburban, exposed, and frankly sterile without their splendid giants.

But back to Suzuki and Grady’s book for another reason to slow down tree loss; this lyrically-written book drives home the fact that the regeneration of evergreens is fraught with hazards. Those trees that reach for the heavens have grown from small seeds that exist because their parents were spared the axe. Each Douglas fir’s parent went through a five-month ‘pregnancy’ before dropping a viable seed which fell into an hospitable environment with sufficient moisture and the right balance of sun and shade. As it grew, each sapling had to escape the actions of hungry deer, insects and drought. Douglas fir survivors can reach 25 feet in 20 years, but relatively few seeds and saplings will make it that far. So you can’t expect that a single mature tree removed will be naturally replaced within your lifetime. Nature left to its own devices will take years or decades to replace that tree, and up to 100 years to grow that replacement to mature size. Buying a small tree as a replacement is not a good option either, for many native evergreens grow much less vigorously in cultivated form than in natural form.

While infant native trees feed deer and insects, those that survive to maturity offer the environment even more. All trees absorb greenhouse gases, sequester carbon, and breathe out oxygen. Dropped leaves, needles and lichens form mats colonized by fungi, invertebrates, and micro-organisms that eventually break down the material down into soil. Birds and small mammals nest in branches. Pileated and other woodpeckers feed on insect invaders and Douglas fir seeds feed our native Douglas squirrel. Western red cedars host native caterpillars that transform into butterflies. All mature conifers provide year-round shade and shelter, but the high branches of mature Douglas firs in particular are favorite nesting and perching sites of eagles. In short, the contribution of a mature native tree to the natural ecology of Point Roberts is immense.

Do you want all this right next to your house? Given their root structures, Douglas firs and Western red cedars are not susceptible to blow-down until they are centuries old, as long as they grow on normal soil and are not damaged or climbed by ivy. They can, however, catch fire, which would be a sensible reason for removing a mature tree. Western red cedars with their high flammability are more likely to catch fire than many trees. So remove red cedars within 10 feet of your house and prune back branches that are within 15 feet of the ground to minimize fire hazard. But please consider leaving other trees to grow and enhance our natural landscape.

Beginning with this column, In the Garden will transition to a bimonthly column supplemented by occasional guest columnists. If you are interested in writing a guest column, please email RhianonAllen@dccnet.com.