Snowdrops, or Galanthus, have flowered here (Chicago area) already. They’re incredibly hardy and perplexing in their ability to push up through hard frosted ground. Sometimes, I’ve seen them come up when there’s snow on the ground, and in those instances, it’s clear that there is a ring of space around the plants, indicating that they’re actually melting the snow around them. Maybe all living things give of heat (?), but I’ve never noticed any plants doing so. This is so obvious that I wonder what’s happening, if their metabolism is different from most other plants, or if I’m misinterpreting what I’m seeing. What’s the straight dope on these plants?
Plants respire - that is, they consume the energy reserves that they earlier manufactured via photosynthesis, and laid down in the form of sugars, starches, etc - this respiration process is exothermic, just like it is in animals.
The reason you’re seeing it in these plants is that they are active - a lot of other plants are still dormant.
Some plants definitely produce their own heat. The poster child for this is the Skunk Cabbage, which melts through the snow and produces heat in order attract insects to pollinate its flowers by scent and for warmth.
Snowdrops are often alleged to produce heat, but I haven’t been able to find any confirmation of this fact. Instead, they probably melt the snow around them primarily because their dark leaves absorb sunlight and heat up faster than the surrounding air.
Are Snowdrops Thermogenic?
I have often wondered this myself.
Is the melted ring of snow around the trunk of a tree due to heat given off by the tree or because the bark is an absorber of radiant energy?
With trees I’d also take into account how much less snow there is near the bole and the little snow there is, is less dense.
I think it’s primarily due to the dark trunk absorbing sunlight and heating up. AFAIK, this happens even with dormant trees with little metabolic activity or sap flow.
It’s been quite a few years since I lived where it snows, but I believe the melted ring of snow occurs around telephone poles too, which would preclude metabolic activity as an explanation.
Plants are not my field of expertise, but I wrote a joint proposal with a plant company & academic group in which one of the phenotypes that was looking to be up-regulated was a temperature phenotype that could increase the plant temperature by as much as 2degC. It seemed like it was transferrable to multiple species including arabidopsis (for testing) and grasses (for deployment). So there are at least known genes for heat production!
There’s no particular reason why the two phenomena must be connected.
I don’t understand that reasoning. If a telephone pole causes snow around it to melt, then why wouldn’t a tree do the same thing by the same mechanism?
Why would there be one singular explanation for snow melting that applies to non-living objects in the same way as it applies to living organisms that have an exothermic metabolism?
Snow cover around the base of large vertical objects such as tree trunks and telephone poles is often thinner than it is in open space, because unless the snow has fallen vertically in still air, the base of the pole is somewhat sheltered by the pole itself - and if the wind is inconstant in direction while the snow is falling, the sheltered area around the base of the pole will be distributed around it.
It could be a bit of both. I have some wooden posts in my backyard that has a melted ring round the base.
It’s plausible that living organisms might produce heat that would cause melting that doesn’t occur near a nonliving object. But I find it hard to imagine what characteristics of a living organism would PREVENT snow from melting, when it melts around a nonliving object of a similar size, shape and composition. Basically you’re saying (if I’m following your reasoning) that snow melts around a pole because of mechanism A, and snow melts around a tree because of mechanism B, so something prevents mechanism A from melting snow around a tree.
Are there any living organisms that don’t produce heat?
Isn’t that what cold-blooded animals, like reptiles, do? Their body temp depends on thet temperature of the environment around them.
Also, I know from experience that greenhouses filled with plants are much warmer than the outside area. I don’t know how much of that is due to heat produced by the plants vs. sunlight retained inside the closed area (or even heat from the people inside the greenhouse).
All organisms respire, and thus produce heat to some degree. The amount may be small. Decomposing leaves produce heat due to the respiration of large numbers of bacteria.
Reptiles produce heat, they just produce much metabolic heat than birds or mammals and they lose it easily since they don’t have fur or feathers for insulation to retain it.
In greenhouses the heat is mostly due to the fact that light that passes through the glass heats the plants and earth inside. The heat can’t escape due to convection because the greenhouse sealed.
…hence the term “greenhosue effect.” Visible light goes in through the transparent glass (or plastic) and is absorbed inside the greenhouse. The warm surface re-emits the heat as infrared radiation, but the glass/plastic is not transparent to infrared, so the heat is trapped inside.
I wonder if we were talking at cross-purpose. Telegraph poles are not similar to snowdrop stems. I was still talking about those - I didn’t notice the posts where trees entered the discussion - apologies for the confusion.
I concede that similar (and purely mechanical/non-biological) mechanisms may apply to the melting of snow around tree trunks vs telegraph poles. That seems reasonable.
Pretty sure (but not 100%) that’s only half-right about how the greenhouse effect works.
Glass is transparent to infrared. The difference is that the amount of energy radiated by warm things as infrared is significantly lower than the amount of energy input by sunlight (because the sun is a lot hotter than the interior of the greenhouse).
What the glass does is stop warm air from escaping and taking all that heat with it.