To the casual observer or the pilot of a low flying Cessna, the West Duwammish Greenbelt is densely green, decidely deciduously green. Big leaf maple and red alder dominate the upper story canopy, in areas these species are overmature, rotten, and falling over, but what lurks below in the “understory” contains a healthy palate of invasive plants – Himalayn Blackberry, English Ivy, English Holly, and several others. Sure there are brilliant exceptions where the invisible hand of the ecological restorationist has worked. But where are the conifers; the Douglas firs, cedars, and hemlocks?
In December of 2013, I assisted efforts with Garden Cycles – Steve Richmond in treating a 5 acre site near South Seattle Community College and the headwaters of Puget Creek. The approach was to cut invasives, paint the cuts with a concentrated form of glyphosate and leave the root system intact to die. Following this treatment we planted 1,000 temperate forest Puget Sound species, many, many conifers. Garden Cycles methodology is sound and follows the protocol of the Green Seattle Partnership on restoration; they are a high grade restoration firm in West Seattle.
However, when, I saw how many years of work (cuttings and conifer plantings) had occured before us, I was awestruck. This site has the typical glacial till clay soils of Seattle. And because of the structure of the forest, there is almost no organic humus, very little fungi, and scant sunlight. What grows is remarkable.
So what occurs after a successful planting? The heavy shade restricts plant growth of anything below: tree, shrub, or invasive plant. During the summer, the clay soils with limited surface fertility lock moisture in their pores and tree roots can’t obtain any moisture to photosynthesize correctly. Result: our plantings survive yet they struggle. Because of restrictive environmetal conditions, these conifer saplings energy resources are taxed during their primary years. They live but do not thrive. It is awesome to see these survivors, but the conditions of their struggle don’t meet the rigorous test of ecological restoration. Pockets of sunlight and patches of mulch would help correct these deficiencies. Other elements could include mychorizza and ants. Lets keep raising the bar on ecological restoration so that successes in the field generate more community enthusiasm for restoration.