climate adaptation

Anyone Tapping Yet?

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When to tap?  That is the question.  And when it comes to maple sugaring, that is THE question.  Currently, we are in the holding position at our Mansfield sugarbush and thankful for the cold temperatures that have descended on the region.  The longer the woods stay cold, the closer our trees will get to meeting their chilling requirement, and the more optimistic I will be when we do eventually start our season.  Put simply, if trees don’t sleep well, they can wake up cranky!

When we look to the south along the Ohio River, I see more good signs of zero accumulated growing degree days since the start of the year.  Note, this does not account for any warm spells we had around Christmas.

With that map in mind, a peek at online chat forums like the Maple Trader’s Ohio Forum reveals that several folks are already tapped in part or in full (January 2nd in Ross County, another early report out of Muskingum County).  Looking even further south to states like Kentucky and West Virginia, only early tappers were rewarded with last year’s ultra-warm and sporadic 2023 season.  That likely pushed some producers to move their tapping date earlier on the calendar.  Still, others are crossing their fingers that last year was an anomaly and going with a more traditional schedule again for 2024.

Taking the forecast up top at face value and speaking directly to our Mansfield site, there aren’t many (if any) quality freeze-thaw cycle days for a truly big run in the next 2 weeks.  If we do decide to tap in a week or so, we should at least get all our lines flushed and spot check the vacuum on the system while we wait for better conditions to kick things fully in gear.

Come back next week for a post from Les Ober where he discusses the question of tap timing and the effects of El Nino as we all wring our hands and stare into muddy crystal balls in search of the right answer to our question!

What Triggers Bud Break? Monthly Maple REVIEW

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A brief introduction to this new feature – Monthly Maple Review – we review a research article once each month to spotlight key findings, investigate curiosities, and uncover important implications for Ohio’s maple producers.  Please comment below if you have thoughts, ideas, insights, or questions.  And if you stumble on to a new maple article and want to see it highlighted in a Monthly Maple Review, please reach out to me via email – karns.36@osu.edu.

“Bud Break in Sugar Maple Submitted to Changing Conditions Simulating a Northward Migration” by Ping Ren and colleagues.  This article was published in 2021 in the journal Canadian Journal of Forest Research.

In our first Monthly Maple Review, we looked at producer attitudes and behaviors regarding climate change and its projected impact on maple.  For this our second installment, we focus on how a simulation experiment predicts climate change will effect bud break in sugar maples.

As climate shifts and range-restricting thresholds follow, plants and animals must adapt and keep up with changes or risk being left behind.  Many organisms are well-suited, at least from a mobility standpoint, for keeping up – take birds and their gift of flight for instance.  Other species likely face serious challenges; the American pika is commonly pointed to as an example.  Pika are small, marmot- or groundhog-like creatures that live in treeless alpine habitat in the Rocky Mountains.  It is easy to imagine pika being literally stranded on mountain peaks above timberline unable to migrate and keep up with shifts in suitable range.  Many plants are also considered less adaptive to shifting conditions and may not be able to move into higher latitudes or elevations necessary to keep up with suitable growing conditions; sugar maples are no exception.

In emergency scenarios, assisted migration is a solution whereby humans literally help other organisms keep up with shifting climate conditions.  Already, experiments have been conducted with many plant species, including some trees such as the whitebark pine, to verify suitability of growing conditions beyond the current limits of the species distribution.  Will sugar maple or other maple species need a special assist from us?  No one knows for sure, but studying what factors drive bud break is a small step to understanding if they are likely to need our help in the future.

The essence of Ping Ren and team’s experiment was to examine bud break under controlled conditions while varying temperature and photoperiod (also known as day length).  The experiment’s most basic hypothesis was that “photoperiod outweights temperature in initiating bud break when the chilling requirement in unfulfilled.”

To understand the study’s results, we first need to wrap our minds around 3 main environmental factors, or signals – the variables we believe most plants are responding to when they wake from winter dormancy and start to stir towards bud break.  First, winter chilling – more intense and longer periods of cold during the heart of winter contribute to chilling.  This deep freeze is what resets the annual clock of trees and influences the trigger of growth reactivation.  Perhaps it is worthwhile to think of chilling as similar to a human experiencing a prolonged session of deep sleep.  Second, spring temperature – this is just what it sounds like.  In a simple system, cooler spring temperatures may wake plants from deep sleep more slowly than a rapidly warming and sudden onset of spring (check out a series we did in winter 2022 on growing degree days to better under the role of spring temperature).  And finally, photoperiod – more commonly known as day length.  The most important thing to note on this final factor is that while any given year might vary in terms of winter chilling or spring temperature, length of day is fixed and will always be fixed regardless of where climate change takes us.

While each factor in isolation is relatively easy to understand, it is the complicated interactions between winter chilling, spring temperature, and photoperiod that likely determine the actual timing of bud break in a species.  This study ran 2 experiments that essentially confirmed the hypothesis that sugar maple bud break is more determined by photoperiod than by spring temperature when the requirement for chilling is not met.  Let’s put that another way – during winters that do not put sugar maples into a deep sleep for long enough (winter chilling), day length has more of an effect on bud break timing than how cool or warm spring temperatures are.  In other words, the experiments confirmed the authors’ central hypothesis.

Let’s unpack that a bit more and talk about some take home messages.

Resetting a sugar maple’s internal clock is accomplished primarily by meeting the chilling requirement – being cold enough for long enough.  When that chilling requirement is not met, it takes additional and louder signals to wake up a tree from dormancy to initiate bud break.  While this might sound a bit counterintuitive, the fact is that waking up a tree from a deep sleep is easier and more predictable than trying to wake up a tree that has been tossing and turning in its winter bed.  Under changing climatic conditions, warmer winters may result in unmet chilling requirements that ultimately result in delayed bud break thereby shortening growing seasons.  But remember, winter chilling is just the first consideration.  What about spring temperatures?

At face value, most sugarmakers understand the effect of a warm spring – trees break bud faster.  In a cool spring, buds stay closed longer and the sap season might last a bit longer too.  In a worst case scenario, climate change wreaks complete havoc on winter weather not allowing sugar maples to adequately chill and temperatures jump back to springtime highs so quickly that any sap season is effectively crowded right off the calendar.  That’s where day length seems to play a crucial and important role.

Think of day length/photoperiod as a speed governor on a go-cart.  I hate so-called governors growing up.  I wanted to ride my go-cart at top and dangerous speeds, but my parents set the speed governor so that I could only drive certain speed limits.  When spring temperatures warm abruptly and it seems that the sugar maples might break bud extraordinarily early, length of day pumps the brakes and slows down that process regulating it closer to normal.  Essentially, photoperiod may be a crucial regulating factor to keep sugar maple bud phenology more on track than would be expected otherwise.  In the authors’ own words – “Because day length will not change under climate warming, photoperiod becomes ultimately limiting when bud break in sugar maple occurs too early.”

So where does that leave us?  Will sugar maple need our help in assisted migration as conditions change faster and faster into this and coming centuries?  Time will tell, but if this study teaches you nothing else – you can certainly walk away with 2 big takeaways.  First, trees are remarkably complex organisms.  And second, trees have a few tricks up their sleeves!

Climate Change & Maple: Who Cares?! Monthly Maple REVIEW

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A brief introduction to this new feature – Monthly Maple Review – we review a research article once each month to spotlight key findings, investigate curiosities, and uncover important implications for Ohio’s maple producers.  Please comment below if you have thoughts, ideas, insights, or questions.  And if you stumble on to a new maple article and want to see it highlighted in a Monthly Maple Review, please reach out to me via email – karns.36@osu.edu.

“A Changing Climate in the Maple Syrup Industry: Variation in Canadian and U.S.A. Producers’ Climate Risk Perceptions and Willingness to Adapt Across Scales of Production” by Anna Caughron and colleagues.  This article was published in 2021 in the journal Small-scale Forestry.

The maple syrup industry is on an undeniable collision course with changing climatic regimes – shifting tree composition, more unpredictable and earlier sap seasons, and potential reductions in yield are all staring back when we look into the future.  This list represents just the tip of the looming iceberg, and more southerly producers anticipate an even rockier path forward as evidenced by some impacts that we can already talk about in the present tense.

Anna and her co-authors are not the first team to survey climate-related issues amongst producers, and perhaps we will review other similar papers down the road.  But one interesting angle, beyond the normal suite of factors like age or education or political affiliation, that this study examined was producer scale.  Does producer scale impact willingness and ability to adopt climate-adaptation practices in maple production?  Let’s first clarify what a climate-adaptation practice is.  Consider the effects of shifting tree composition in Ohio.  That shift will likely lead to increased dominance by red maples.  Adapting to that effect would be to tap a diversity of maple species, not just sugar maples.  Failing to adapt to shifting tree composition could lead to reduced tap quantity because of unwillingness to tap anything except a sugar maple.

With that point clarified, two over-arching findings stuck out to me.  First, nearly 90% of all surveyed producers agreed that maple syrup production is closely linked to climate, and only 15% of small producers (<2,000 taps) believed climate-induced impacts would be a net positive to their operation.  How often does that lop-sided a percentage of folks agree on something?  Not often.  Second, larger producers are more willing to adopt more climate-smart adaptation practices than medium or small producers.  And guess what, political affiliation had nothing to do with any of the above.  Yes, you read that correct – climate and maple is apolitical.

Before we dive into the specifics, know that it took 10,000+ taps to be categorized as a large-scale producer in this study.  Quite frankly, most US producers in this study were small or medium, and most Ohio producers would certainly be “small.”  A final caveat, before we dive into a few specifics, is that among the 354 survey respondents in the study, only 12 hailed from the Buckeye State.

Canadian producers, which are also more likely to be the “large” producers, are more apt to fertilize their sugarbushes and practice intensive silviculture, but significantly less likely to increase the number of trees they are tapping.  I can see the practice of fertilization.  Personally, I believe all maple producers – regardless of scale, should practice active silviculture in their maple woods.  The goal of active silviculture after all should be healthy maples!  The last point about tap quantity is a hard one to understand…until you discover that rules enforced by the Federation of Quebec Maple Syrup Producers prohibits most producers from increasing their tap count.  Given that most large producers are also Canadian, the pattern of stubbornly maintaining tap count then makes some sense.  I certainly learned something new with that fact pointed out to me.

“Medium” producers were more likely to tap earlier, implement rigorous sanitation practices, and stay up to date on latest research finding than “small” producers.  Multiple factors could be play as “large” and “medium” producers increasingly differentiate from “small” producers.  I’ll quickly highlight just one factor as I grapple with the study’s findings.  Some “small” producers are undoubtedly hobby producers.  Making syrup is fun and as soon as it seems like work, well…where’s the fun?  I can easily see why an individual producer with 100 or 2 taps would decide not to invest in high vacuum efficiencies.

Putting aside scale of producer and applying the lens of producer age, we learn that tapping red maples and using high vacuum systems are less likely among older producers.  Only focusing on the practice of tapping red maples, this fits within the pattern of a traditional no-no generationally passed down.  Not until more recently has University research been dedicated to documenting production potential in alternative maple species.  What’s that saying about “old dogs?”

I’ll wrap this review up by pointing a finger back at myself – a maple educators.  This sentence from the study speaks for itself, “Only 20.9% of producers…thought that information on climate change impacts on the maple industry was easy to access.”  Yikes, that is a huge wake-up call and harsh criticism for the University community.  Hopefully this site can help address these knowledge gaps for Ohio maple producers, and this Monthly Maple Review series is part of the solution.