What is the Edge Effect?
Every planting, whether in a garden, a plantation or even natural bushland has an edge effect where plants meet an open space. This open space means the plants along the edge are more exposed to the elements of wind, frost or sun. These elements are like bullies, constantly attacking the integrity of the plants till they succumb. This exposes the next layer of plants, and so the degradation continues, slowly and insidiously.
All plantings have an edge so what can we do?
A garden with a solid fence provides some protection from the elements, but not all plantings can be so lucky. Single trees in an open parkland type garden or paddock, are exposed to the elements all around. farm plantings that are long and skinny of two rows have an edge all the way around. But a planting with three rows will have one row that suffers less from the edge effect. Creating a planting with a greater middle, such as a square, is more effective.
Multiple layers of plants can help to mitigate the edge effect. These layers ideally consist of grasses, small shrubs, tall shrubs and trees. This allows the wind to be broken down as it moves through a planting.
Even in natural areas the edge effect can be seen, like the photo above, with plants struggling along the edges from the elements, but also from weed invasion. In suburban areas, this could be escaped exotic plants or introduced grasses, slowly making their way into the natural area. Or in rural areas with gorse, hawthorn, broom and blackberries. The weeds slowly invade the lower layers of ground covers, and the grassy and shrubby layer, till the integrity of the bushland is compromised, and we are left with only trees and weeds. The picture below shows gorse invasion along the edge.
When outdoors, we naturally seek out shelter from the elements, and what we like, plants also like . Understanding the edge effect helps when creating sheltered spots in a garden for barbeques and entertainment areas. Wind seems obsessed in finding us, so creating multiple layers of plants to create a hiding spot is ideal, and of course, this also creates the ideal habitat for birds also seeking shelter from the edge effect.
And so, just like us in our lives, it's about creating a strong centre so we are less vulnerable to the vagaries of those attacking our integrity.