Atlantic Forestry January 2021
/Planning for resilience
How’s the old woodlot going to hold up to climate change?
by David Palmer
On Nov. 10, when a workshop was held in the scenic Picadilly Hills just east of Sussex, N.B., to discuss forest management in relation to climate change, the temperature was a heavenly 23.4 degrees Celsius – which seemed fitting, just to underscore the point.
The event – hosted by the Southern New Brunswick Forest Products Marketing Board (SNB), the New Brunswick Federation of Woodlot Owners (NBFWO), and Community Forest International (CFI) – was the culmination of two years of work and study that led to the development of a practical guide entitled “Climate Change Resilience and Carbon Storage Silvicultural Prescriptions for the Acadian Forest Region” (aka, the C&C Decision Tree). The manual, commissioned by CFI, was prepared by Gareth Davies, with input from Megan de Graaf. Following release of the first draft in 2019, CFI partnered with the NBFWO to refine this management tool, and to deliver “capacity-building activities” for forestry professionals. The project has been financially supported by Natural Resources Canada and New Brunswick’s Environmental Trust Fund.
“At-risk species won’t be doing so well, whereas resilient species will have good growth,” said Megan de Graaf, of Community Forest International. “If you follow these keys, and if you manage your forest to become more resilient to climate change, then you are inherently growing more wood.” (David Palmer photo)
The workshop offered lots of great information, and generated lots of thoughtful discussion, causing me to re-examine the way I look at my woodlot. (More on that later.) We visited four sites, but before we got started, Chris Spencer, manager of SNB, urged us to think outside the proverbial growth-and-yield box: “Now that we are looking at these stands and recognizing what’s in front of us in terms of climate, it forces you to question. What species are going to be challenged in the future, and what ones are going to prosper? Are the boreal species that we tend to put a lot of commercial weight on going to be able to tolerate the changes that are anticipated?”
Spencer then led us through the C&C Decision Tree. The only prerequisite to following the steps is a basic understanding of forest ecosystems and a knowledge of how climate change is expected to affect forest composition and species resilience. Megan de Graaf, of CFI, has made the latter part easy by summarizing and compiling the research in 2018. Under a moderate climate-change scenario for the period between 2040 and 2070, no species disappear – but there are clear winners (such as beech, Red maple, ironwood, White pine, and Red oak) and clear losers (Balsam fir, Jack pine, White spruce, and Large-toothed aspen, among others).
The first site was a 40-year-old Red spruce stand that was thinned 10 years ago. The Decision Tree presented us with a series of questions:
Is the stand dominated by a single effective age class? Yes.
Is it in the stand initiation stage? No, it’s already well established.
Is it in the stem exclusion stage? You bet.
Is the canopy composition acceptable?
We need to hit the pause button before answering that fourth question. Prime growing conditions for Red spruce are in the cool, damp, coastal climate associated with the Bay of Fundy and most of Nova Scotia. Many people think of the Maritime region as having a homogeneous climate, but that is far from the case. In 2020, Fredericton experienced 68 days when the temperature exceeded 25 C, while Yarmouth managed only 12 days; parts of Nova Scotia’s South Shore, in Zone 6, are often snow-free all winter, whereas northern New Brunswick is typically buried under two metres of snow, and is solidly in Zone 3. Under a moderate climate-change scenario, Red spruce is expected to persevere, especially in its optimum Maritime habitat – but further inland, where significant warming is expected, it may come under stress. Sussex is on the cusp – much warmer, but still somewhat influenced by the Bay of Fundy.
The experts in our group predicted this stand would do fine if left alone for another 40 years, but since there was little regeneration, another option was posited by Spencer: “Maybe we can sequester more carbon if we do a light thinning and try to establish the next crop.”
Leaving that question hanging, we moved across the road and upslope about 100 metres into a mixed, uneven-aged stand comprising White spruce, White pine, Red maple, and Large-toothed aspen. Here there will be winners (the pine and the maple), and losers (the spruce and the aspen). Options include waiting five years and re-assessing; scattering Red oak acorns; and roughing up the ground by harvesting the spruce and poplar, to improve the seedbed for White pine.
Our third stop was lunch – chicken wraps, super-size peanut butter cookies, and drinks – providing enough energy for the slog uphill through a thick carpet of leaves to an upland hardwood site. This stand was dominated by sapling-stage diseased beech and a few older trees that were in decline, with a sprinkling of ironwood, White birch, Red maple, and Sugar maple. Here and there, a clean, healthy beech appeared.
From a climate perspective, beech is expected to do well. So too are ironwood and Red maple, while Sugar maple is expected to hold its own. What to do? The site was a fuelwood operator’s dream, yet we knew that if the beech were cut, the openings would become choked with suckers. Even though beech is climate-resilient, it is not desirable, due to its 96 percent rate of infection with canker. The Decision Tree asked us: “Can desirable regeneration be established through silvicultural treatment?” A “no” answer led to the recommended treatment: understory planting of low-risk intermediate to shade-tolerant species. A few scattered seedlings of White pine were already getting a foothold, so this would be a strong candidate.
It was a good day, providing valuable new perspectives on forest management options. There are many woodlot owners whose primary objective is not to produce timber, but rather to have a place for recreational enjoyment, cutting firewood, and protection of wildlife. I count myself among that group, although I still enjoy watching trees grow and seeing the changes that come about after a harvest. To manage successfully for an uncertain climate future, you must know what you have on your woodlot, and what condition it’s in, and then take corrective action if necessary.
FRESH EYES
For the remainder of the fall, I spent a lot of time studying our own woodlot through fresh eyes, and thinking about what it would mean to apply the lessons learned – specifically, how climate change will affect each individual species. Our most abundant species is Red maple, followed by Balsam fir, cedar, Large-toothed aspen, Yellow birch, scatterings of all three spruces, and a few ancient White pines.
The good news is the Red maple, New Brunswick’s most populous hardwood, whose range extends from Florida to Newfoundland. This opportunistic species is already expanding its presence in the forest, and it is expected to prosper under climate change. There are plenty of younger trees to replace the older ones that I target for firewood, which are starting to crash to the ground. However, management for carbon storage calls for leaving some full-cycle trees to live out their whole lives, then replenish soil carbon with their rotting trunks, so I might have to fine-tune my firewood harvest strategy. That aligns with the idea of leaving a few old bruisers as fodder for the Pileated woodpecker who inhabits the woodlot.
Balsam fir, especially on woodlots in southern New Brunswick, is a problem child. Like Jack pine, and Black and White spruce, it is a boreal species, and much more at home in the Christmas Mountains or the Cape Breton Highlands. Much of the fir on our woodlot dates back to budworm attacks in the late ’70s that killed the overstory and laid down a blanket of new fir, which has been thinned and is now approaching merchantability. It has been afflicted by lots of pests – the Balsam woolly adelgid a few years ago, and now the Balsam gall midge. The midge was so bad in Charlotte County this fall that wreath makers had trouble finding good tips. Contending with the fir will be our biggest priority for the next five to 10 years.
As for White pine, there are some old giants, and a bit of regeneration from them, so one strategy might be to encourage this species’ re-establishment while selectively removing merchantable fir and maintaining shelterwood conditions. White pine is expected to do well under a warming climate, and it could potentially replace the struggling fir during the next century. A loamy knoll near the camp might provide a suitable trial area for starting that transition, which could include underplanting if natural regeneration doesn’t adequately respond.
The climate jury is still out on my favourite tree, the Yellow birch, but its current range extends south into New Jersey, so I am not worried about its imminent demise. There is a band of them growing by the little seasonal brook that skirts the woodlot, and I have been nursing them along for the last 30 years. The Ruffed grouse come at dusk and scale their branches, looking for seeds that have not yet been dispersed. Like cedar, spruce, tamarack, and Grey birch, Yellow birch just love a freshly bulldozed roadbed; they all crowd together on the verge, as I puzzle over how many can be retained while still keeping the road open.
Next to fir and Red maple, cedar grows best on the woodlot, thanks to an underlying bed of lime. When local markets boomed 25 years ago, we cut 200 cords or so, but lots remain. Many of the elders exceed 100 years, while young ones pop up everywhere, in the shade or in the open. Like Yellow birch, cedar is expected to persevere in a warming climate, even though it prefers more northerly habitat. Except for the occasional brute that may be harvested for a specialty project, the old cedar will be preserved, while new growth will be protected and cherished.
Large-toothed aspen is abundant on the woodlot, and it’s in great shape, with some approaching two feet in diameter, although a few are starting to upend. It is a wonderful tree, with vitamin-rich buds that are a favourite snack food of Ruffed grouse, and pure white wood that makes superb trim and mouldings. Oddly, the PICUS climate model predicts the decline of more southerly Large-toothed aspen, while suggesting that Trembling aspen, a boreal species, will persevere. Our arboreal bible, Trees in Canada, shows the range of Large-toothed extending well down the Atlantic seaboard, so I am hopeful for the future of this distinctive and cheerful species.
When it comes to spruces, the few scattered Whites are tall but tired-looking. They will be spared the saw for the time being, and may become legacy trees. The Red spruces, on the other hand, are younger and perkier, and they appear to be on the rebound. By scuffing the duff layer and exposing mineral soil as we diligently reduce the fir population, we may help new spruces in getting established, and maybe the woodlot is close enough to the Bay of Fundy to support healthy Red spruce. The small contingent of Black spruce occupies a pocket wetland that they share with tamarack and cedar, and they will be left alone unless somebody needs a canoe paddle.
You may have gathered that the plan for increasing our woodlot’s climate resilience involves a lot more harvesting than is currently taking place. The only way to change forest composition is to guide the transition through careful harvesting (and possibly planting). Assuming a growth rate of one cord/acre (five cubic metres/hectare), which is adding 80-90 cords a year to the growing stock of our woodlot, my measly annual harvest of four or five cords hardly amounts to a hill of beans. Moreover, harvesting is not incompatible with carbon storage. In fact, commercial thinning will yield as much carbon storage over 30 years as doing nothing – and more if the trees are afflicted by insects and disease that cripple their CO2 uptake.
The final word goes to Megan de Graaf, who pointed out, “Climate change resilience is the primary objective, carbon storage is secondary, and timber production is a by-product. However, at-risk species won’t be doing so well, whereas resilient species will have good growth. If you follow these keys, and if you manage your forest to become more resilient to climate change, then you are inherently growing more wood.”