three p’s of shelterbelt success
Shelterbelt success:
There are three necessary conditions for shelterbelt success: planning, planting, and post-planting care.
Planning
The most important phase of shelterbelt planting is the planning phase. During the planning phase of the operation, the goal is to come up with a planting prescription suitable for the land type, area, and desired outcome.
3 row shelterbelts
If the purpose of the shelterbelt is primarily agricultural (e.g., to prevent soil erosion and block wind), the 3 row shelterbelt is the ideal choice. In a 3 row shelterbelt, species are chosen according to canopy type and growth pattern. The general rule for a 3 row shelterbelt is to plant a row of shrubs on the windward side, a row of fast growing deciduous trees in the middle, and a row of evergreens on the leeward side.
Row 1 (windward): Shrubs
Buffaloberry
Dogwood
Row 2: Fast growing deciduous trees
Poplar
Larch
Row 3: (Leeward) slow growing everygreens
Spruce
Pine
Some sources recommend up to 6 rows per shelterbelt. For most purposes, a 3 row shelterbelt should suffice to get the job done. That being said, there is a time and place for larger shelterbelts. If the purpose of the shelterbelt is to block unwanted odours (say, from a slaughter house), then a 3 row shelterbelt will not provide the intended benefit. In cases like these, it is best to go for more rows.
Spacing
Rows of trees should be spaced apart at intervals of 3-5 meters, and intertree spacing should be between 2.5-4 meters, depending on the type(s) of tree being planted. Larger intervals should be used for conifers and deciduous trees. Shrubs can be spaced closer together, or between the gaps between larger trees.
We recommend the 2-3-4 rule: 2 meters between shrubs, 3 meters between deciduous trees, and 4 meters between conifers.
Size of the shelterbelt
Once you’ve settled on an arrangement of rows, the next step is to decide on the number of trees to be planted. It may be the case that one leg of a shelterbelt only requires a single coniferous row of trees, while others require 3+ rows.
If the goal is to block wind, have a look at the prevailing winds in the area. Historical records and current wind conditions can be found through ACIS. Legs that run perpendicular to the prevailing winds will require more rows than legs that do not, and areas with strong seasonal winds will require more rows than areas less prone to high wind velocities.
Planting
Prepped v unprepped land
As a general rule, it is a good idea to prepare the land into which you will plant a shelterbelt. The purpose of preparation is twofold: (1) to break up compact grassmat, and (2) to expose plantable mineral soil. Land preparation can be done up to a year before trees are planted, but best not to leave it any longer than that.
Unprepped ground may also be planted, but it can be difficult. Grassmat and compact soil can make the process more challenging. Without planting experience, it is very easy to plant a poor tree in unprepped land. If you intend on planting into unprepped land, it is best to hire a professional.
Quality
The main rule of thumb is that the plug must be straight in the ground and covered on all sides with mineral soil. Avoid planting shallows, J-roots, and open holes.
Shallows: a tree that isn’t deep enough. A shallow tree is a tree whose plug is not fully covered by mineral soil. As such, the root system is at a high risk of drying out, and the tree has little chance of thriving.
J-Roots: a tree whose plug is bent. J-roots are caused by jamming a tree into a hole that’s not quite deep enough. A tree with a J-root might appear to be a good tree, and may survive a few years, but will eventually topple over.
Open holes: a tree planted in a hole that isn’t properly closed. Like shallow trees, trees planted in open holes are susceptible to drying out.
The extent to which it is easy to plant a good tree will depend on your prior planting experience and the type of land being planted. Planting raw land is difficult, but planting prepped land can be much easier. Other factors like rockiness, moisture content, loaminess, and compactness will contribute to the overall difficulty of planting.
Post-planting care
When it comes to shelterbelt trees, there are two tasks that any post-planting care regime must accomplish: (1) weed suppression and (2) irrigation.
Weed suppression
Weed suppression strategies come in two kinds: natural and artificial. Natural weed suppression involves installing a mulch layer around individually planted trees. It is the cheapest option available, but also the weakest method of suppressing vegetative competition. The surest way to prevent vegetative competition is to opt for artificial weed suppression, usually involving landscaping fabric or plastic mulch. Artificial methods tend to be more expensive - material and labour costs are both greater for artificial weed suppression compared to mulch.
Mulch
Choosing a mulch layer as your weed suppressant is the cheapest and most sustainable option when it comes to weed suppression. Install a mulch layer over each planted tree. The mulch cover should extend 50 centimeters from the tree on all sides, and should be 5-10cm deep.
When installing mulch around a planted tree, make sure to leave a gap around the tree itself. If a sapling is crowded by mulch, it is at an increased risk of root-rot. A length of 2-inch pvc can be placed over each individual tree while mulching to prevent contact between stem and mulch.
Landscape fabric
Landscape fabric is a sure way to decrease the vegetative competition around your newly planted trees. It is also costly. Traditionally, rolls of landscape fabric are unfurled along the entire length of a shelterbelt. This unrolling can be done either before or after planting, depending on a number of factors.
If the land is soft, prepped, and free of rocks, you should have no problems planting trees through the fabric. Once it is on the ground, use a sharp object to cut holes into the fabric at the prescribed spacing. Trees can then be planted into these slots.
If the ground is unprepped, or if there are any major planting difficulties involved, it is best to install the fabric after planting. To properly plant a tree in tough grounds requires some degree of microsite selection. In this case, planting through the landscape fabric is not a good idea, since there is no way to adjust the microsite once a slit has been cut into the fabric.
Irrigation
The second prong of successful shelterbelt maintenance is irrigation. The amount of water required varies by species, location, and environmental conditions. For most species, the danger of over-watering is just as great as not watering enough, so it is important to tailor your irrigation regime to the individual traits of your shelterbelt.
Drip irrigation
For some, the best option is to install a drip irrigation system. The advantage of doing so is that no special labour is required to water your trees. The disadvantage is cost. The cost of installing an irrigation system can exceed the cost of sourcing, planting, and mulching your trees combined!
For large tracts of land and commercial shelterbelts, the added cost is worth it. But for smaller projects, or for projects constrained by budget, the best option is to adopt a manual watering strategy. For the most part, trees will only need to be watered a few times a year, give or take, to help them power through summer draughts.
Whatever irrigation set up you choose, remember to pay close attention to the appearance of the young trees as you go about watering them. A thirsty tree will have a wispy, straw-like appearance. Its leaves may be cracked or brittle. An overwatered tree will look sickly, though not dry.
