Photo (Source: https://www.newlifeonahomestead.com/swales/) A maturing berm – acting as swale – yard debris piled on contour to the land and planted over time – the woody compost creates moisture and nutrients to grow more plants and trees.
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By Brandon Bauer, Permaculturalist, Salt Spring Island – reproduced from Island Tides Regional Newspaper, March 8, 2007
With outdoor burning banned all summer long there is a tendency for a pile to accumulate in one corner of the yard. This pile usually consists of slash, branches, stumps, scrap wood, lumber with nails, perhaps a little cardboard, and other things generally called garbage or waste. These piles range from small home-sized to large development slash piles.
Energy can neither be created nor destroyed, and a tree is a battery collecting the sun’s energy. We know that smoke, when we burn wood, is pollution, or waste. Wait, there’s that ‘waste’ word again. Waste equals unused energy. We are actively polluting our air, our communities, and our families while wasting valuable unused energy.
Wood waste is biomass, or nutrient matter. The lifecycle of a tree starts as a seed. By using the carbon-based energy of its predecessors mixed with sun and water, it grows to be the largest living organism on the planet, defying gravity for as much as 120m.
At the end of its life cycle, a forest tree falls, bringing other trees down with it, leaving a twisted mass of crossed trunks and branches. Leaves and needles fall off depositing a collection of nitrogen and minerals on the forest floor. These initial nutrients awaken dormant soil organisms, the decomposers—various types of fungi, and micro fungi.
After these little creatures have finished breaking down complex carbon chains, then insects and other critters like sow bugs, termites, centipedes and even slugs come in. Along with water, these and other natural systems redistribute the tree’s (originally the sun’s) energy throughout the surrounding environment, making it accessible for the next generation of trees.
Imagine a group of trees standing on a hillside. What you see makes up only 50 to 55% of the total mass of those trees. The other half is living below the earth. When it rains, a tree uses its leaves and branches as a means of slowly funneling water to its trunk roots. Its leaves and needles slow the rain from pelting to earth and flushing away the food supply the tree has deposited on its own roots. Once the water has reached the forest floor, the woody litter holds the water, allowing it to percolate into the soil.
A tree in a forest environment holds the equivalent of its weight in water in the soil, and can support more than 10,000 living organisms in our climate. In the tropics, the number of organisms supported is ten times higher.
When our forests are cut, land de-stumped, and branches burned we set the stage for unnatural events. Do any Salt Springers remember what happened to Blackburn, Cushion Lake, and the Fulford-Ganges Road last winter? Two properties in the Blackburn Lake Watershed were cleared of trees. The resulting surge of run-off and sediment clogged culverts forcing the lake to overflow onto the Fulford-Ganges Road.
Berming is an Alternative
I am not saying that cutting trees is inherently bad and I am not telling anyone not to do it. I heat my home with wood and live in a wood home. I am also a carpenter and find wood to be an attractive building material. What I am recommending are more thoughtful land development and stewardship practices.
So what is a Berm? A berm is a giant woody compost. The difference between a berm and a compost pile is that with a berm you don’t have to turn, screen or move into your garden. A berm stays in place, and feeds the already present soil flora. You can add to it, you can make it a permanent fixture. Berms, over time, can become great wind, noise, and light screens. They can also be planted with trees that further protect your house from outside influences. If one were to quantify the potential mass of a development’s burn pile, it is the equivalent of one tree for every two trees-worth of lumber removed.
So, when we burn, one-third of the total biomass of a forest ecosystem ends up in the atmosphere. As we are beginning to learn, the greatest impacts humans have on our environment are carbon emissions and airborne particulate matter. Much of this gas and particulate could remain on the ground to breakdown. If we place this biomass in piles or rows across the contour of a slope, we begin to use our biomass to slow water, filter run-off and hold that precious water in the land.
Berms also make great habitat. Wrens, sparrows, towhees, and juncos are just a few of the native birds that move in and find a warm protected home. Berms also act as mulch or tree habitat. If we plant our berms with shrubs, hedges, and trees, then we can really take advantage of the rich biological activity happening in a constructed ecosystem.
From adding diversity to your gardens and homes, to saving water, blocking wind and noise, and creating habitat for local wildlife, berming has a place in a well-stewarded environment. We may want or need to harvest trees, yet this does not mean that we need to pollute the atmosphere while stripping the forest floor of all the available stored energy. Burning slash piles has a huge impact on your family, your community and your environment. The land belongs to the future generations of every living thing that exists today.