This story appeared in the Winter 2015 edition of Our Big Backyard, a quarterly magazine about parks and nature. Read more stories, plan an outing with a field guide, and find out more about fun nature events and classes.
Does one tree matter?
It does to the more than 50 arthropod species, including spiders and insects, which make their homes within the deep canopy of Douglas firs. And those spiders and insects matter to the dozens of species of birds that forage for arboreal arthropods to feed their young. One old-growth Douglas fir tree can serve as the base of a food web that benefits thousands of flora, fauna and fungi.
In the land conservation and restoration world, we sometimes focus on size: acquiring big parcels, restoring long reaches of streams, creating wide wildlife corridors. But small matters, too. Protecting a grove of trees or a tiny parcel of land can significantly benefit conservation and restoration efforts.
Metro recently acquired three parcels within the River Island Natural Area on the Clackamas River. Each parcel is about half an acre – less than the size of the Timbers’ soccer pitch. Alone, each parcel of land provides little in the way of protection for water quality or wildlife habitat. Yet, each was an essential acquisition. Acquiring them closed a gap in the protected natural area, allowing our large-scale restoration work to move forward.
Just as land acquisition happens on the large and small scale, so does restoration. Tucked within several of our larger natural areas are steep canyon walls with crevices, small areas of rock fall and rocky outcrops. These features are uncommon in our forest-dominated landscapes and might appear harsh and unwelcoming for wildlife.
But for an intriguing range of wildlife, these rocky features are five-star hotels. Long-tailed weasel, bushy-tailed woodrats, western skink lizards and rubber boas all shelter, forage or breed in these areas. Cliffs, caves and crevices are also used by several local types of bats, such as long-eared bats and big, brown bats.
These habitat features cover only a small fraction of the more than 17,000 acres of land that Metro protects, but we pay attention to them during our restoration work.
So how exactly do we restore rockfalls, cliffs and crevices? It’s mostly done through a process of subtraction and avoidance, with a little construction work where appropriate.
We subtract the invasive species, such as ivy and clematis, which aren’t inhibited by steep, rocky walls.
Occasionally, our restoration work includes placing large boulders or constructing piles of loose rock that wildlife use as basking or den-ning sites.
Then we avoid the areas. All wildlife species are sensitive to disturbance during certain times of the year, such as the breeding and rearing season. Bats and reptiles are particularly vulnerable to disturbance in winter. If they’re disrupted during winter hibernation, they must burn up precious energy with no way to replenish their reserves.
I don’t always know the full roster of wildlife using Metro natural areas, but I always assume some wild animal is taking advantage of every ecological niche, from the single, big tree to the crack in the cliff wall to the wild river reaches.