To my surprise, I learned from Rainer and West, “When soil is exposed to sunlight, rain and extreme temperature changes, it is damaged,” and its stored carbon is oxidized and released as carbon dioxide. “The longer a soil is exposed, the harder it is to vegetate later.”
Like many suburbanites, I’ve had the fond belief that unplanted areas would be fine for indefinite periods if they’re covered with mulch.
|I thought mulch was enough to protect soil.|
Apparently this is better than leaving soil bare to the elements, but it’s not the best approach.
It seems that roots and plants’ “underground storage organs” (more on this somewhat risqué phrase in a future post) are crucial for building functioning soil. The channels dug by roots open up space for air and water. When roots decompose in fall and winter, their organic material stays behind as humus, storing carbon and nutrients in the soil. That’s good for plants and good for the climate, too.
|Dense groundcover is healthier for soil|
Both author duos describe natural landscapes in terms of plant layers. Among the broad landscape types, my yard is closest to a woodland edge. In this kind of landscape there’s a canopy layer formed by trees, a woody understory of lower trees and shrubs, and an herbaceous layer of perennials and grasses, ranging down to the lowest plants that cover the ground.
This week I moved some bearded iris that were blocking our view of the fish pond and replaced some tired moss phlox (Phlox subulata) with five pots of bearberry (Arctostaphylos uva-ursi). Their spot is one of the most visible in the yard, within clear view of the kitchen windows.
|The fish pond in August|
The bearberry plants join the groundcover layer, and I hope they’ll stay low and neat-looking. I had pulled out some moss phlox a few weeks ago and left the soil bare before covering it with bark mulch last week.
|Bearberry and bare soil. I hope it will fill in next spring.|
Both sets of authors emphasize the benefits of a rich and diverse groundcover layer for providing habitat for insects and other small organisms. Native bearberry should help in this regard. I’ve certainly got lots growing at ground level. Over the years I’ve planted something in just about every inch of garden soil.
When I squeezed in those little plants I couldn’t resist bringing home, of course, it was to help the environment. As one of this year’s presidential candidates would say, “Believe me!” And I’m willing to do even more shopping for the sake of the earth.