Study- No winter halt in below-ground wood growth of four angiosperm deciduous tree species

[Linn01]

Interesting reading material for a cold winter evening. Abstract to be found here:
https://www.creaf.cat/en/articules/deciduous-trees-roots-remain-active-winter

 

[BrianBay9]

Fascinating! I'm curious how roots continue to fix carbon without photosynthesis? Building wood from already fixed carbon - stored sugars - I get. But are they suggesting roots are capturing carbon from CO2? From some other soil components? Transfer from symbionts? This article was not clear on that point.

In re-reading the article they talk about deciduous trees fixing carbon in winter, but then talk about using "stored carbon" for wood production. To my way of thinking stored carbon = sugars. So the trees don't "fix carbon" found in CO2. I think that portion of the article is misleading.

 

[Melospiza]

Yeah I don't understand why the article makes it sound like trees capture carbon in winter, rather than just converting sugars into woody tissue. Also that bit about nutrients and proteins makes it sound like roots somehow produce them in preparation for spring growth. How?

 

[Wires_Guy_wires]

Fascinating! I'm curious how roots continue to fix carbon without photosynthesis? Building wood from already fixed carbon - stored sugars - I get. But are they suggesting roots are capturing carbon from CO2? From some other soil components? Transfer from symbionts? This article was not clear on that point.

In re-reading the article they talk about deciduous trees fixing carbon in winter, but then talk about using "stored carbon" for wood production. To my way of thinking stored carbon = sugars. So the trees don't "fix carbon" found in CO2. I think that portion of the article is misleading.

I think the researchers differentiate between fixed in wood (long term fixation) and stored as sugars/starches (short term, or 'not even fixation' since it's not actually fixed in place).

 

[Gabler]

The article seems to imply that this is new information, but we've always known that. Any one of us could have told them that roots continue to grow in the winter, and trees store carbohydrates and nitrogen compounds in their roots in preparation for spring growth.

 

[ShadyStump]

The article seems to imply that this is new information, but we've always known that. Any one of us could have told them that roots continue to grow in the winter, and trees store carbohydrates and nitrogen compounds in their roots in preparation for spring growth.

It's been speculated here many many times, and often stated as scientific fact, but until now we've yet to see much hard research shared here. I chock it up to finally conducting the science to support what we've previously only observed anecdotally. Seems small, but now that it's proven (more or less,in scientific terms) researchers can use the exact data we now have to start more detailed analyses of exactly what trees' needs are during dormancy, and more importantly HOW dormancy happens at all. In many ways it's actually a big deal.

 

[Notsureaboutplantnames]

Reading the abstract, they do not mention C fixation by the roots which would be pretty amazing unless there were some photosynthetic microbes living in the outer bark of the roots.

The term fixation may have been used in this brief article to mean C reallocation for continued "differentiation of xylem cells in growth of the older roots".
It does introduce an interesting question: How much of the reallocated C is then available for shoot growth from the roots. The roots are a long way from the developing spring buds in many trees.

I understood that energy from bud swelling came from stem stored C and nutrients while new leaves are photosynthetic and also act as sinks from stored C in the stems. Summer or late spring growth uses newly translocated nutrients from the soil.

What an interesting rabbit hole that lead to. Thank you.

 

[dbonsaiw]

The article seems to imply that this is new information, but we've always known that.

Yup. I put my grow boxes on the ground in early November and come March the roots have escaped the box.

Does this mean that the notion that roots basically stop doing their thing below 40 degrees is simply not true?

 

[doc spring _work]

I think an important thing to consider is the article just says "deciduous trees such as" and don't include the specific species... Diving into the abstract of the source article is also vague about what species were studied, I know articles and studies I've read following Aspen indicate the bark has photosynthetic ability even in dormancy they photosynthesize... That said it's possible these species have a similar capability, I think we are all aware of tree roots growing in winter and I'm certain more studies examining the behavior of roots in prolonged dormancy might be an interesting study..

Particularly I wonder if it is as we assume and a trees roots are using up stored energy or if deciduous species in general may have the capacity to photosynthesize in winter through most bark, of course the only study in aware of studying photosynthetic capabilities was on aspens back in the 50's

Looking back at my thoughts from this article I think I really need to go back to college and actually dedicate myself to trees as they clearly occupy fat too much of my thoughts far too often

 

[doc spring _work]

A Conceptual Framework for Winter Dormancy in Deciduous Trees

The perennial life strategy of temperate trees relies on establishing a dormant stage during winter to survive unfavorable conditions. To overcome this dormant stage, trees require cool (i.e., chilling) temperatures as an environmental cue. Numerous approaches have tried to decipher the...

www.mdpi.com

Very good read covering the history of studying dormancy, unfortunately didn't cover any root studies... And I've yet to find any open publications covering the subject.

Half Tempted to preform my own study on the subject, id want a temperature controlled environment that I can still provide plenty of light to... And id also need to likely use a see through grow set up to observe root growth over the dormant period...

I remember discussing sage at the nursery a while ago and my coworker assisted in a study watching the roots of that plant, I recall they had difficulty because the plants roots avoided the light, they ultimately covered the observation window up with a temporary cover so they could periodically view and measure growth...

This is of course theoretical. I'm not sure I could afford the set up required for this much less any material costs but still something id love to try one day,

What would your set up for a study of this kind look like?

 

[ShadyStump]

What would your set up for a study of this kind look like?

Off the top of my head I'd see about clear acrylic pots, and an opaque planter of some sort to set the pots in. Periodically pull the pots out to observe root density. That, however, leaves you estimating root growth, but no firm measurements.

Ideally you would start with several sets of identically aged plants of the same species, all in individual pots/planters. Grow them all year, then randomly select some right at the start of dormancy to weigh, and perhaps chop up to weigh top vs bottom growth. Then do it again at the end of winter just before the break of dormancy. Do this for several years in a row.
There'd be a lot of variables to cover, though, like soil moisture, the seasons' specific conditions, etc. Best to do it in a controlled environment like a cold greenhouse or the like.

 

[doc spring _work]

Off the top of my head I'd see about clear acrylic pots, and an opaque planter of some sort to set the pots in. Periodically pull the pots out to observe root density. That, however, leaves you estimating root growth, but no firm measurements.

Ideally you would start with several sets of identically aged plants of the same species, all in individual pots/planters. Grow them all year, then randomly select some right at the start of dormancy to weigh, and perhaps chop up to weigh top vs bottom growth. Then do it again at the end of winter just before the break of dormancy. Do this for several years in a row.
There'd be a lot of variables to cover, though, like soil moisture, the seasons' specific conditions, etc. Best to do it in a controlled environment like a cold greenhouse or the like.

That's what I figured, I think the easiest way to do it would be a cold green house. Also using a shallow/wide pot may make measurements easier if done appropriately.

I'm primarily interested in extending the dormancy of groups and see if they all manage to survive under a mild temperature prolonged dormancy, I'm certain an Aspen would be the best subject given we know they photosynthesize during winter so that would provide a good baseline as the control species to determine if other deciduous have a similar and/or weaker capability, I would assume that our common understanding of roots using stored energy is likely true but I'm not sure if it's been studied (I can't find a study at least...)

The expected outcome would be death in the most prolonged test If this is true as the tree wouldn't be producing any starches/energy

Alternatively if an average deciduous trees can exhibit growth without an sign of slowing/stoping/dying it's possible we don't fully understand dormancy in its entirety but that outcome seems unlikely using aspens as a baseline as the only deciduous species (I'm aware of) that we know photosynthesizes in winter

 

[ShadyStump]

That's what I figured, I think the easiest way to do it would be a cold green house. Also using a shallow/wide pot may make measurements easier if done appropriately.

I'm primarily interested in extending the dormancy of groups and see if they all manage to survive under a mild temperature prolonged dormancy, I'm certain an Aspen would be the best subject given we know they photosynthesize during winter so that would provide a good baseline as the control species to determine if other deciduous have a similar and/or weaker capability, I would assume that our common understanding of roots using stored energy is likely true but I'm not sure if it's been studied (I can't find a study at least...)

The expected outcome would be death in the most prolonged test If this is true as the tree wouldn't be producing any starches/energy

Alternatively if an average deciduous trees can exhibit growth without an sign of slowing/stoping/dying it's possible we don't fully understand dormancy in its entirety but that outcome seems unlikely using aspens as a baseline as the only deciduous species (I'm aware of) that we know photosynthesizes in winter

Well of course we don't fully understand dormancy. 90% of why most people are interested in it is for the orchard industry, and they had most of what they really need to know figured out 100 years ago. The rest just an interest in understanding biology in general. I imagine, though, that there will be more interest in it in the future, between climate change, and space colonies, and just little other direction to go with the science.

If you're specifically trying to study whether or not it's photosynthetically derived growth, Aspen is a great choice, but I personally suspect there's something more to it. Biochemically related phenomena in the root system itself.
Like I said, most of what we know is about orcharding, but also mostly focused on the above ground portions of the tree since that's the money making part of it. If they want to learn more they'll have to start digging.

 

[Notsureaboutplantnames]

A wholesale nursery owner once (or more) told my class on a field trip,"Everything Peter is teaching you is wrong, we just don't know it yet."
One of my favorite lines in science.