For us forestry people, the cycle of forestry is clear. You plant, you thin two or three times, you clear-cut, and then you start again. That’s what we are used to and what we are supposed to do. In many countries, e.g., Sweden it is mandatory according to the Forestry Act to reforest after a clear-cut. You can use natural regeneration instead of planting, but that still demands some actions, such as ground preparation. But what if you don’t do anything?
Managing the forest from the couch
We have written about reforestation and how it’s supposed to be done. We also wrote about how the forest manages itself if we don’t do anything, but that article was focused on old forests. But what if you just let it be after clear-cutting? Will there be a new forest then? Will it be profitable? The only thing that seems sure is that the cost of reforestation is zero, and that’s a good start – financially.
In the northern hemisphere birch is a pioneer species, meaning it’s the first species that comes up after a clear-cut or wildfire if nothing is planted. Here in Sweden, pine and spruce are the dominating species and what our forest industry asks for. Birch and other hardwood species have been “thinned away” for decades because of that, but since the certification standards have become more important that is now changing. And not only that …
With increasing pulpwood prices for birch in Sweden, the interest in it has increased among forest owners. As birch, as mentioned above, tends to come by itself, it’s tempting to just let the new clear-cut be and see what happens. Recent research claims that the chances are fair under the right conditions.
My colleague Torbjörn Johnsen at the sister site Skogsforum.se decided to have a look at a 20-year-old natural regenerated birch stand that hadn’t been touched at all since the clear-cut.
20 years ago, a sturdy spruce forest was harvested on this site. After that, nothing has been done. Today the stand is dominated by silver birch (Betula pendula). In wet areas along a ditch, some alder (Alnus glutinosa) grows, and single spruce trees are seen here and there. The tallest birches are approx. 15 – 20 meters (49 – 66 ft.) high.
No measurements were made in the stand (the height was estimated) but looking at the photo above it seems that the time now could be right for a thinning. Considering the form and size of the stems, and the high pulpwood prices, a harvester thinning would be profitable here. A thinning will make the tree’s diameter grow and 8 – 10 years from now the next thinning could be made. 25 – 30 years from now this stand can be harvested with nice thick birch timber.
Is it profitable compared to spruce or pine?
For the moment, the forest owner gets more for birch pulpwood than for spruce- or pine pulpwood. But that hasn’t always been that way. It differs over the years, has always done and will always do. Therefore, it’s difficult to give a good answer to the question. It depends on supply and demand, and wood prices.
One must consider that “doing nothing” means that you will have no costs for ground preparation (scarification) and planting. But for a good result, you must do at least one early pre-commercial thinning. If you do, you might get a profit already by the first commercial thinning, and then by all the coming actions up to the clear-cut.
Spruce would probably give more profit by the time of harvest, but the spruce has a longer cycle than birch. You can harvest the birch earlier and save time, and money(?). And, to get a good spruce stand you most likely must scarify and plant and, like the birch stand, do pre-commercial thinning.
You can’t stay on the couch too long
If you ask me (right now you have no choice), it seems a bit risky to just let a clear-cut be and do nothing. If you happen to have a stand like the one in the photo above, I can only congratulate you. But there is no way the ones who let this happen there, knew that the birch prices would be good in 2023, or that the stand would develop that good.
I recall working in Germany as a harvester operator in the 90s, and a German forester who asked me “How can you be so sure that pine and spruce will be marketable 100 years from now?” Well, what do you reply to that? He, of course, referred to the fact that we (Sweden) only grew pine and spruce for over 150 years.
Today we know that there are many benefits to mixed stands, Biodiversity, soil improvement, wildfire prevention, etc. Furthermore, the FSC (in Sweden) demands that at least 10 percent of the stems in all stands should be hardwoods by the time the stand is ready for clear-cut. That means that you must leave much more, maybe up to 40 percent, in the early thinning to achieve that.
If you leave a birch-dominated stand for free development too long, spruce will eventually take over. To get a mixed or a pure birch stand you need to be active and make sure the birch gets the space it needs. So, don’t stay on the couch too long.
There is a lack of knowledge about birch (and hardwood in general) management in Sweden. That is because the only commercial species that have been interesting are Scots pine (Pinus silvestris) and Norwegian spruce (Picea abies). This is slowly changing due to growing awareness about the risks of monocultures in the ongoing climate change. In the last 20+ years we have received more demands from the certification standards which also contribute to a growing will to grow mixed stands of soft- and hardwoods.
However, this knowledge is about to grow. An example of that is a doctoral thesis by Ms. Felicia Dahlgren Lidman at the Swedish University of Agricultural Sciences, SLU, called Natural Regeneration and Management of Birch, published in 2022. All in English, just click on the name of the paper here above and start reading.