Last updated on October 23rd, 2023 at 09:01 pm
The amount of light a plant receives is important because it most often determines its growth in the riparian zone.
For a long time the simplified grid was used:
- sun: more than 8 hours of sunlight;
- semi-shade: from 4 to 8 hours of sunlight;
- shade: 2 to 4 hours of sunlight.
In order to better respond to complex sunlight conditions, another grid has been developed by a horticulturist from the Montreal Botanical Garden:
- full sun: more than 8 hours of sun during the hottest part of the day;
- light shade: light shade created by trees or buildings, accompanied by sunshine during most of the day;
- Semi-shade: 4 hours of sun or shade from the edge of trees or buildings during the hottest part of the day;
- shade: less than 2 hours of sunlight per day or shade from buildings or trees, but which provides minimal light;
- Dense shade: place that receives no sunlight, only indirect light.
It is important to remember that in a riparian buffer, especially in areas with trees, the level of sunlight varies over time. For example, herbaceous plants and shrubs in a newly planted riparian buffer will not receive the same amount of light four or five years later, when the trees have developed. Most often, full-sun plants will die out naturally and be replaced spontaneously by better adapted plants. However, it is sometimes necessary to intervene in order to ensure the effectiveness of the riparian buffer and especially to avoid runoff problems created by the death of certain plants. In some cases, pruning or the addition of better adapted plants must be considered.