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| Introduction |
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What is the correct density? Windbreaks can serve many functions, including crop protection, snow control, livestock protection and as visual screens. Each of these purposes has its own range of appropriate densities. The density goals can be met by using the correct combination of tree/shrub type, number of rows, and within-row spacing between plants. Table 2-2 shows the recommended within-row spacing for specific purposes, according to the North Dakota Natural Resources Conservation Service.
Table 2-2. Within-row spacing by plant type to meet specific purposes. Note the range of appropriate densities for each goal. (From North Dakota NRCS Windbreak/Shelterbelt Establishment Design and Installation Guide.)
* The minimum square footage per plant means that a design using minimum within-row spacing will often require wider between-row spacing in order to ensure enough growing space for each plant. Adequate growing space per plant will maintain a healthy, vigorously growing plant, with a reduced chance of disease incidence, and a strong likelihood that lower limbs will be retained throughout the life of the planting.
** Rows of conifers or deciduous trees should not be planted within 25 feet of cottonwood, hybrid poplars or tree willows, nor should these plants be alternated within the row.
Not with one row � When planting multiple rows, use within 4ow spacings of a 40-70% dense planting.
The appropriate density depends on the goal of the windbreak. Densities greater than 80% are used for snow control and as noise barriers. Protecting livestock and building sites require 60-80% density. Traditional crop protection requires windbreaks with only 40-70% density while snow spreading needs low densities (35-60%) with very little at the bottom (trees pruned at least 10 feet high, no shrubs used in the windbreak).
The following �Density Quiz� offers real-life examples of windbreaks that may or may not be fulfilling their functions. This 10-question quiz will offer you the chance to improve your understanding of the appropriate windbreak densities. Although you don�t have to take the quiz to move on to Component 3 of this course, it�s highly recommended that you take it.
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What is the correct density? |
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