This beautiful, mature second‑growth coastal temperate rainforest is only ten minutes from my house. I should get there more often, and perhaps I will after taking an interest in ecosystems in addition to geology. Today’s outing was an opportunity to begin acquainting myself with the ecosystem I inhabit, so I made an effort to identify several plants along Five Mile Drive, a road that circumnavigates the forest and is permanently closed to auto traffic. When I started walking along this path, this forest was nothing but a lot of green trees and stuff. My perspective changed over an hour or so, and about 2.5 miles.

This colorful maple tree is a native to Puget Sound. It earns its name because those deeply lobed leaves are up to a foot across. But what are its roles in this forest? CoPilot had a lot to say about that. The Big Leaf Maple is fundamental to this ecosystem because it creates a huge amount of leaf litter that contributes to the forest floor and thus supports a vast microbiome, as well as a nurturing environment for conifer seedlings. This large tree (50-150 feet) fills in gaps in the forest canopy, supplying shade and catching rainwater, as well as dew. Its dappled shade creates a diverse understory for new growth. It is important in the success of birds, insects, bats, squirrels, and deer. They all hang around it and depend on its large mass for homes and meals. Its large root system contributes to hydrologic stability by stabilizing slopes, slowing runoff (and erosion), retaining moisture, improving soil infiltration.

This large tree is native to SE Europe and they were introduced after the logging boom led to immigration. However, it is not an aggressive invader; this lovely tree does not form thickets, outcompete conifers, spread wildly, alter soil chemistry, suppress understory diversity, or create monocultures. In CoPilot’s words, “It’s a polite non-native.”

This nondescript shrub gives the forest its lush, evergreen understory identity. It is one of the top berry producers in the Puget Sound lowland forest but, more importantly, its berries ripen later in the season, extending the berry window into early fall. It also thrives in the acidic soils Douglas fir and hemlock create, in turn moderating soil conditions. It bridges the gap between ecological disturbance (i.e. logging) and late-successional forest. One could say that it serves as a node in the forest’s ecological web. This is an unrecognized keystone species in the understory.

Oregon grape is the huckleberry’s silent partner in keeping the understory secure because it is also an evergreen shrub. In addition, it supplements the food web by blooming in March-April, providing nectar when few other shrubs are in bloom. Its berries ripen by mid-summer, bridging the gap between early berry producers like salad and late huckleberries. It precedes huckleberry in forest succession but persists as the canopy creates a shadier understory.

Himalayan blackberry is less like the fruit-bearing huckleberry and Oregon grape, and more like the Trojan Horse. The fruit are abundant and sweet, produced for a long season, and loved by all the denizens of the forest; thus, they are spread like wildfire, colonizing the entire forest–without predators in Pt. Defiance. The result of this invasion includes impenetrable thickets, root masses that choke other species, spreading by long, arching canes, and monocultures. It kills all the other stabilizing shrubs and creates a single mass of Himalayan blackberry. If left unchecked it can destroy an entire ecosystem, including the conifers. Holy shit!

This nitrogen-fixing tree is the first responder when the forest is disturbed. As such it enriches soil, accelerates forest recovery, feeds the next generation of conifers, increases understory diversity, boosts fungal activity, and generally improves growth rates of proximal plants. Alder is the first tree to reoccupy damaged land, preparing the site for the conifers that will come later. Wherever alder stands exist, the biodiversity of the forest is increased. Because it gives so much to the forest, alders only live 40-60 years, thus acting as a continuous healing agent as a forest recovers from an environmental shock. This is the pioneer tree of the lowland forest. I hope it can defeat the Himalayan blackberry.

This view of the Tacoma Narrows bridge through the thick forest reveals a green landscape perched atop high bluffs overlooking Puget Sound. As far as the eye can see, from this vantage point, the forests were clear-cut to make profits and fuel the economic development of the Pacific Northwest.

But at what cost?