I'd like to throw out a suggestion that may be useful for a few foresters: Take a close look at your planting specs. To be clear, I'm not saying, "Let us plant shitty trees."
Instead, I'd like to take a close look at the science and math behind certain specs, specifically as they relate to spacing/density/excess. I'm going to refer to the FS 704 system which is used by BC government offices, and also used by many private mills throughout the province and in Alberta.
One of the goals when the FS 704 was designed was to build in a "spacing tolerance" to allow the planter some leeway in picking the best microsite, or the best spot to plant a tree. Yes, hitting a specific target density within a block is important, but the designers of the 704 system didn't want to be so rigid that planters would simply plant a tree at the perfect spacing every time, with no regard for how suitable that microsite was for the tree. If there was no spacing tolerance, the benefits of hitting density would be outweighed by decreased yields and increased mortality from trees being planted in poor spots. A planter might plant a tree in a pile of sticks or needles or chunky red rot, instead of planting in a microsite only 12 inches away that had appropriate soils.
In general, depending on the region, spacing tolerances usually allow for about a meter of tolerance. For example, if the target spacing is 2.7m between each tree (thinking in both the X/Y axis, or both "ahead" and "laterally") then a simple generalization is that a tree is considered to be good if the tree is somewhere between 1.7m and 3.7m away from all of the other trees around it. You don't want all of them to be only 1.7m away from the others, or all of them to be 3.7m away from the others; you want a healthy mix of some closer and some further, so the overall average spacing still balances out to be pretty close to the target (2.7m in this example). However, this variability or spacing tolerance allows the planters to feel more comfortable in looking for the best microsites for the trees, without having to worry too much that they're going to get faulted for "tree too close" or "missed spot" penalties. Having a spacing tolerance is ultimately what's best for the plantation, as long as the planters utilize the tolerance to hit the best microsites for the trees.
We've seen an increase over the past several years in the amount of FFT (Forests For Tomorrow) funding on reforestation contracts in BC, mainly due to wildfire restoration. Traditionally, the average target spacing on BCTS and MOF contracts within British Columbia was usually in the range of 1400-1600 stems/Ha (except on the coast). However, a lot of FFT funding is attached to projects and blocks where the target spacing has climbed to 2000 stems/Ha or even more. And I'm not disagreeing with this change. A lot of the wildfire damage has come in pine stands, for multiple reasons (pine is more dominant on dried ground, mountain pine beetle has killed and dried a lot of standing pine, etc.). Pine is a species which grows better at higher densities. If you're going to plant one stand at 2400 stems/Ha and another at 1600 stems/Ha, and you have pine for one stand and spruce/fir for the other, you're almost certainly going to plant the pine in the high density stand.
The problem is that while densities have frequently increased from 1600 stems/Ha to 2000 stems/Ha, there hasn't always been a corresponding drop in "minimum acceptable inter-tree distances" (MITD), more casually known as "minimums." The minimum spacing on 1600 stems was usually 2.0m between trees. Unfortunately, the minimums on some 2000 stem target densities are still set at 2.0m.
To be clear, for non-foresters who are reading this, a 2.0m minimum means that if you plant two trees and they're 2.1m apart, that's acceptable. If they're 2.0m apart, that's acceptable. If they're less than 2.0m apart, one of the two trees gets faulted as a "too close" tree, which gets counted as a quality fault under the FS 704 system, and a reduction in the assessed quality of the block means a reduction in payment to the planting company.
Let's look at the TARGET spacing distances that are required to meet various densities:
Under a target density of 1600 stems/Ha, all trees are supposed to be 2.7 meters apart (on average). This means that with a 2.0m minimum, the planter has at least 70 centimeters (on the close side) to work with. There's also a tolerance on the "further apart" side, but the method of calculating that exact distance is complex (it relates to "missed spot" assessments). Let's just focus on the close side. Under a target density of 1400 stems/Ha, the trees need to be about 2.9m apart, which means that the spacing tolerance before being assessed as "too close" has increased to 90 centimeters.
Let me switch focus for a moment here, and go back to the goal of hitting the best possible microsites for the trees. On some planting contracts, foresters ask for "obstacle planting" to come into play. This approach asks the planters to plant seedlings beside an "obstacle" to maximize growth and/or survival. Typically, logs and stumps are viewed as excellent obstacles (unless root diseases in stumps is a consideration). A planter can even consider a big rock to count as an obstacle if there are no stumps or logs that are close enough. There are different reasons why obstacle planting is useful. In cattle country, a cow is less likely to step on a seedling if it is very close to a stump or log. In the Alberta foothills of the Rocky Mountains, a tree planted on the correct side of an obstacle is possibly protected from chinook winter winds that lead to exposure and desiccation (snow is a good insulating blanket in the winter). Anywhere that extreme heat is a problem, a tree planted on the northeast side of an obstacle is usually protected from the hottest afternoon sun, at least for the first couple years. Expect obstacle planting to be useful then in both cattle country and in the most southern regions of Alberta and BC. The relative "direction" of the obstacle (in relation to the microsite for the seedling) is important when weather-related, and unimportant when cattle-related.
If a planter is being asked to seek obstacles, the spacing tolerance comes into play. Depending on the terrain, there may be anywhere from a few to a dozen "acceptable obstacles" in a plot. When there are less obstacles than trees, it becomes obvious that not every tree can have an obstacle. It also becomes obvious that the planter has to think carefully about where to put trees, in order to maximize the use of any obstacles that are available.
Let's say that there are only five useful obstacles in a given "plot" (a section of the block covering 50 square meters). Without delving deeply into the math, you can multiply the number of obstacles in a plot by 200 to come up with the expected number of obstacles in a full hectare (because 50 square meters is 1/200th of a hectare). So if you multiply 5 x 200 you get 1000 obstacles per hectare. You can use the same spacing chart above to see that the obstacles, on average, are about 3.4 meters apart.
If the "perfect spacing" for your next tree puts the tree in a very specific microsite, and you have a 70 cm spacing tolerance away from that spot, what is the chance that you'll be able to utilize a good obstacle if the average spacing between obstacles is 3.4 meters? You might be close enough to an obstacle to use it, or you might not be. You'll certainly be able to hit some of the obstacles in your piece, but not all. The math (and spacing rules) may make it impossible to hit all obstacles. But a larger spacing tolerance is better than a small one.
Going back to the high planting densities on FFT funded work (usually 2000 stems/Ha), the planters don't have a lot to work with in cases where the minimum has not be adjusted downward. For 2000 stem density, the average spacing is 2.4m. If the minimum is 2.0m, the planters only have 40 centimeters to work with. Look down at the ground (or floor) right now, and imagine that. If you put an "X" on a specific spot, you have only a little over fifteen inches of flexibility that you can use to move the tree from that "X" and still be within your tolerance. What's the chance that you'll be able to find an acceptable obstacle in that very small area?
If the MITD does not allow for sufficient spacing tolerance, it leads to planters planting in bad microsites, rather than encouraging good microsites.
My camp planted a BCTS contract last year with target spacing of 2000 stems/Ha, a minimum of 2.0m, and a requirement to try to utilize obstacles. It was terrible. The science made it almost impossible for the planters to meet all three requirements simultaneously. They made a valiant effort. When I said that 2000 stems/Ha was the priority, they could do it. When I said that no trees could be closer together than 2.0m, they could do it. And when I said that they should try to hit obstacles, they did it. In fact, they could even do any two of those three things simultaneously, with no problems. But doing all three simultaneously was almost impossible. My solution was to ask the forester what should be sacrificed. There wasn't much movement on minimums, and I was told that obstacles were really important, so I said that my only solution would be to tell the planters not to worry much about the density. I told them to consider obstacles and minimums to be very important. Although a density of 2000 stems/ha was requested, there were no penalties in the contract for planting a lower density. However, there were penalties for planting trees too close (B1, a quality fault) or not utilizing the obstacles. In the end, we ended up having tons of trees left over after we finished planting all the regular blocks on the contract, and we had to scramble to find a number of overflow blocks to accommodate the rest of the trees. This was a challenge, both for us and for the foresters. But in the end, it was the inevitable choice.
I see that a lot of contracts this year, in one region in particular, are once again asking for that difficult combination of 2000 density, obstacle planting, and a 2.0m minimum. That's unfortunate. I would think that the industry would realize that this is a big mistake, and these specs are very problematic for planters. And "problematic" leads to higher bid prices. The problem could be mitigated by reducing the MITD down to 1.6m as acceptable. Foresters would be more likely to achieve their planned densities, and there would be better utilization of obstacles. In many other regions, minimum spacing ranges from 1.5m down to as low as 1.0m.
For this year, I've asked my employer to bid especially high on those contracts, because I don't want my camp to work there. For foresters who are trying to manage their budgets, a bit of flexibility on these specs would lead to more competitive bidding. In the past, I've really enjoyed working with the foresters in the region that I'm referring to. But in the end, I have to think about the best interests' of my planters, and seek to work elsewhere.
If you want to follow public bid results on tree planting contracts within British Columbia, visit this link:
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