Just going over the Academy course in the App and there is a section of energy. Ryan mentions that the two times to work on the tree are when they are in an energy positive state, early spring and then just before autumn vascular growth.
My question is what about the post hardening off pruning that get’s done? Where does this fit into the energy state of the tree?
After watching the video it seems to me this is probably the worst time to be doing this or have I got my wires tangled?
I think the part you’re missing is that there’s a point later in the spring where the leaves are creating enough new energy that it starts to balance out the energy spent in the early spring. The timing marker Ryan uses for this is when the leaves harden off. After that point the tree has more energy than it started the spring with and is now ‘energy positive’.
Post flush harden pruning is done when the tree is in a reduced energy state after having expended a lot of energy producing the spring growth, but not having time to recover it all. The point of this is that the growth generated after the post flush pruning will be weaker and therefore should have shorter internodes and smaller leaves.
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This is not how it was explained in the video which is why I brought it up here. From what I understood from the video this is actually the time that the tree is in it’s most energy “negative state” as all the energy was used to push out all this new growth. That is what is confusing me as to doing some post hardening off pruning.
I am glad someone else finally asked about this. About a year ago I had the same inclination I asked and never got answer.
Energy positive -Energy Negative are not static states
According to the video bud swell before the leaves open in the spring is the highest energy positive state in the tree. All of the stores resources from the previous year are invested and made new cambium highways which allows for additional leaves (solar panels).
BUT it’s not truly Energy Positive because it’s not photosynthesizing AKA getting a positive return on last year’s investment.
So it’s actually more like Energy Neutral with a huge bet “in play”. Once the leaves start opening up until they harden off, the tree is Energy Negative. Once they harden off the extra leaves (solar panels start recouping the newly gained energy with the additional solar panels) the longer and more solar panels you let “into the game” at this the higher return and more energy can be invested into the next “energy positive” cycle.
So when it is growing it’s energy negative, hardened off would be energy positive in between are a series of liminal states.
I think the confusion is that trees are more diversified in their “investment portfolio” than the terminology allows for.
They do not have a single reductive option the way this language suggests…I gained 40% energy from last year and I am investing it in 20% new cambium and 20% new leaf mass.
I don’t know if this is correct but the way I think about it now is…
We repot in the spring because it’s a free roll of the dice, it’s the optimal state to get the best return on the activity. It has the most “bets on the board” with the gains of the previous years returns.
When it opens up and is pushing growth it’s energy negative ( don’t touch it)
when it hardens off it is (at the beginning of energy positive the longer it’s allowed to collect resources unchecked it’s increasing its “energy positive %” depending on what your trying to accomplish and the strength of the tree you can perform an action aligned with a desired outcome…post harden flush and partially defoliation too reduce most of the “winnings” forcing the tree to push smaller “bets” aka leaf size reduction. Instead of allowing it to make $200 bets across the board your action turns the leaves into $40 bets across the board.
Again I agree with you the language is confusing. I think it most be a useful model but it never actually “added up” cognitively but it allowed me to map it the way I just tried to mention.
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This is correct but you have to think of it at the beginning and lowest point of the “energy positive” state. It’s a “phase shift” the temperature when water starts turning into steam…all of the water doesn’t instantly shift into “steam” or “ice” at a certain temperature…it’s the tipping point to start the phase shift
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Obviously all of these are 2D conceptualized models and have limitations. This needs to be stated and is less obvious than our brains want to believe.
the menu is not the meal and the map isn’t the landscape
We can not come close to capturing the totality of what is going in a complex, dynamic, no linear, complex adaptive biological system that is relational to so many variables (including sets that are unknown and even unknowable “unkown-unkown”).
With that being said models and concepts like this can give you more of an understanding but you should hold them as partial at best. I tried to use the language of complexity Science here to ground it in some truth. So the words have distinct non interchangeable definitions. Complex is not the same as Complicated. Hopefully this helps, although I worry it might have made it appear more complicated…sorry not the intention.
I will take a menu but not mistake it for the meal!
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Really like this explanation and seems to make more sense. I really would like to know if it is the way it works. I am just trying to wrap my head around what the state of the tree is in the post hardening off phase of the growth. It makes sense what you’re saying that the tree is in a more neutral phase of energy though.
I would also say that in thinking about it once those first few leaves start pushing the tree is starting to gain back energy. Like @NEBeech says, this isn’t an on/off switch but rather a balance of various functions in the tree. So after the leaves have hardened off the tree has expended the “saved up” energy from the previous fall and will now start again saving with the leaves it has put out for the next fall. So if we remove some leaves this just means that less energy will be stored back into the tree? I also didn’t even think about partial defoliation and how this effects the whole system and the timing of it.
I want to correct this. I should have said “the tree is making more than enough energy to sustain itself”.
In my understanding the new leaves are already photosynthesizing and generating energy before they harden off. I believe the thinking is that once the tree is making more energy than its using, it creates the cuticle as a bit of insurance. To be clear, I’m not aware of any science that says the one causes the other, the timing might just coincide.
@NEBeech points out that this isn’t the tree’s most energy positive time. This is true, at this point we’re just out of the red and back in positive territory.
The point is, hardening off is a useful timing marker for energy break-even. Knowing (approximately) when the tree breaks even will let you time your pruning around this marker to get the response you want from the tree.
@tangled_tanuki Since your really going for the true understanding let me add a few more things to consider. I obviously dont know the answer at the level your after and I too would like to know.
This is based on my understanding and anyone should correct a mis-step!
The tree does not put all of its stored reserve in play in a single season and they are not all allocated to the leaf. Newly gained energy (carbohydrates) has to be used to lay-down cambium (new tissue) and first develop the highways to support the additional transportation of water/carbohydrates to the bud tips. The better the previous year, the better the infrastructure.
There is also a mechanism that serves as “emergency reserve” that accumulates over time (like a 401K) this is not part of the “short term energy strategy” invest what you gained last year. It is an adaptive response that allows for trees to handle unexpected rare events buying it time to either recover from that situation or adapt of time. This is where you get the ability for black pines to develop a long term adaptive strategy to be pinched. The selection pressure caused by the environment Tsunami season over long enough led to the genes and strategies of the JBP to store energy in case of bud break during these months outcompeted a single flush variety.
I dont know if “hardening off” is more about “energy break even” as it is about hormone allocation. Hormones are what signal the growth “energy” is by product or response of the hormone signaling. So perhaps the hardening off is considered safe because, now the tree has its “growth GPS” aligned AND recouped its “vulnerable energy bets” AKA unhardened off leaves.
I put a request into Leigh on the Apex forum asking about a way to get answers to a question of this nature, so if you are unable to parse it out perhaps one day Ryan might be able to explain all the way down to the level desired and point out the limitations of the conceptual model.
@MartyWeiser any thoughts on where we got lost on this?
Thanks for the feedback. I might just also be overthinking it but there are some gaps here in my knowledge that are confusing me.
That would be awesome to get Ryan’s feedback to go into these types of questions and go deep to work out all the wrinkles. Maybe something that could replace the live video’s.
So I think the issue is that terms Positive|Negative are two “states” therefor it suggests a binary state (One or the other ON|OFF) you cant think about it in this way and have it make sense. Its not an “OR” situation. Positive and Negative are a gradient or on a spectrum or even as a flow.
When the tree is trying to send out leaves, or recover from something, it is in a Negative state (or using stored energry=energy negative). The energy reserves (potential), so it is called energy negative.
There is always a flow of energy going on, unless the tree is dead or dormant. Water and nutrients flow from the roots to the leaves, and the leaves then use those and the sunlight to create sugars and starches to flow back down to the roots.
When the leaves have opened up and they are not yet hardened off, it is reaching the end of the enegry negative gradient and when it hardens off it enters the beginning of energy positive gradient. Now this state continues to become more efficient over time and sending BACK more (energy) than they are using, this is continuing along the energy positive gradient.
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