"Nice Rig" [work]

[rebeccmeister]

In general my Tuesdays in the spring are exhausting, because they are long lab days.

Yesterday was one of those days where it took me an extra hour in my office after lab had finished, to muster the energy to ride home. In other words, an especially exhausting lab day.

I have a real love-hate relationship with the lab that we carried out. The overarching goal is to measure animal metabolic rates for a range of animals that vary in size. We work with our available ectotherms that will fit in our available metabolic chambers, so that includes the reptiles, the frogs, and several different insect species - the first introduction to working with insects, which always elicits a range of reactions. The hardest part of the lab is getting each respirometry setup dialed in.



Respirometry setups are always a jumble and maze of tubes and wires. Getting the tubes and wires connected in the proper order requires a systematic approach. Even once that is all together, getting the measurement software configured is another journey, as is calibrating the oxygen analyzers and carrying out a basic sanity test to get an appreciation for the system response times (air flow rate plus tubing volume mean a delay before changed gas compositions reach the analyzers).

One of the comforts in all this work, is that my plant physiology colleague and I have been collaborating to incrementally upgrade the instruments we use for these experiments. This year we sent in our old carbon dioxide analyzers for service, but learned that it isn't possible to get replacement components for them anymore. The ultimate outcome of that is that we wound up ordering a brand-new set of CO2 analyzers, and then also had our original analyzers returned to us, so we have plenty of analyzers to go around for the time being.

I just thought it was cool to get to see how a person might use the same tools that I use to measure animal metabolic rates, to turn around and measure plant photosynthetic rates, along with stomatal opening and closing patterns.



What's neat about the plant setup is that the leaf light level can be adjusted, so then the effects of changing the light level (or type!) on photosynthetic rates can be characterized. This setup also includes a temperature-humidity monitor to track stomatal opening and closing. I hadn't appreciated that it can take a plant a good 20-30 minutes to open its stomata when it's time to ramp up photosynthesis rates, but then stomata can be closed again fairly quickly if conditions change.

My colleague shares my pain of having to spend the entire lab period running around from group to group to try and get students to figure out how to put together their setup correctly and then troubleshoot all of the thousand different issues that come up.

Comments

Thoughts

[ysabetwordsmith]

>> I just thought it was cool to get to see how a person might use the same tools that I use to measure animal metabolic rates, to turn around and measure plant photosynthetic rates,<<

Well yeah, they both respirate oxygen and carbon dioxide, just counterpoint to each other.

>> along with stomatal opening and closing patterns.<<

The way I describe transpiration is "Trees sweat so you don't have to!" My yard, which has lots of trees, averages 5-10F cooler than the surrounding monocrop fields.

>>What's neat about the plant setup is that the leaf light level can be adjusted, so then the effects of changing the light level (or type!) on photosynthetic rates can be characterized. This setup also includes a temperature-humidity monitor to track stomatal opening and closing.<<

That's fascinating.

>> I hadn't appreciated that it can take a plant a good 20-30 minutes to open its stomata when it's time to ramp up photosynthesis rates, but then stomata can be closed again fairly quickly if conditions change.<<

Well, yeah. In most circumstances, light levels will change slowly (e.g. dawn/dusk) whereas stomata sometimes need to be closed quickly to avoid problems, like when a hot dry wind suddenly springs up so the plant needs to avoid losing all its water.

>>My colleague shares my pain of having to spend the entire lab period running around from group to group to try and get students to figure out how to put together their setup correctly and then troubleshoot all of the thousand different issues that come up.<<

Yeah, it's hard to learn a complicated rig like that, let alone how to troubleshoot it. Sometimes it helps to have a steplist and numbered parts, but inexperienced hands will still lose their place. Often though, you'll find one or two students who figure it out quickly and can help. But in biosciences, you're dealing mostly with nature-smart people, and they frequently have an anti-knack with technology.

Re: Thoughts

[rebeccmeister]

With our Biology sequence, it seems to me we wind up favoring students who have more of a cellular/molecular bent. Our college does also offer a major in Environmental Studies and Sciences, and I think a lot of the more nature-smart folks wind up heading in that direction instead. But the students with the cellular/molecular bent aren't necessarily better-equipped for the challenges they face in my Animal Physiology labs!

The flipside of that is that it's clear to me that they need these labs in order to develop skills they aren't developing elsewhere!

Re: Thoughts

[ysabetwordsmith]

>> With our Biology sequence, it seems to me we wind up favoring students who have more of a cellular/molecular bent. <<

That seems fairly common.

>> Our college does also offer a major in Environmental Studies and Sciences, and I think a lot of the more nature-smart folks wind up heading in that direction instead. <<

It matches my observations.

>> But the students with the cellular/molecular bent aren't necessarily better-equipped for the challenges they face in my Animal Physiology labs!<<

Hee!

>> The flipside of that is that it's clear to me that they need these labs in order to develop skills they aren't developing elsewhere! <<

Books teach information, labs teach skills. Knowledge is not much use unless you know how to apply it.

Re: Thoughts

[twoeleven]

The way I describe transpiration is "Trees sweat so you don't have to!" My yard, which has lots of trees, averages 5-10F cooler than the surrounding monocrop fields.

Welll... all plants transpire. I couldn't find a list of rates, but corn is a very thirsty crop, suggesting a high transpiration rate. One study at one site found that corn transpires as much as apple trees, though how this relates to your trees is beyond me.

I can make a number of guesses as to why farm fields would be warmer than a shaded back yard, but I gotta wonder how you got measurements of the nearby fields.

I haven't forgotten about posting more stuff about the Big Whoopsie. It's sitting in draft, waiting for me to round up some spare brain cells to reorganize and polish it.

Re: Thoughts

[ysabetwordsmith]

>> I can make a number of guesses as to why farm fields would be warmer than a shaded back yard,<<

I'm sure the shade is part of it, but so is transpiration. Various studies have look at street trees, yard trees, forests, etc. and found that they are notably cooler than other types of terrain.

>> but I gotta wonder how you got measurements of the nearby fields.

Walk or drive out of the yard. We're surrounded by monocrop, either corn or soybeans. We have a little weather station that gives us the temperature, and the car has a thermometer for outside air too. But it's so dramatic that you can feel the difference just walking from the yard to the field or road.

Now it makes me wonder if the trick still works with dryland trees like manzanita, which try to hold onto their water. I know the effect is more than just shade, because studies have compared tree shade to, say, building shade and the trees are cooler.

Re: Thoughts

[twoeleven]

I'm sure the shade is part of it, but so is transpiration.
Oh sure. But that's part of what I'm getting at: corn transpires like mad¹. No idea about soy.

1: Corn hybrids for developed-world markets transpire like mad. For that matter, so did a lot of open-pollination corns the Native Americans grew. The drought-tolerant hybrids that I know of not only close their stomata in response to water stress, but slow their metabolisms overall.

Various studies have look at street trees, yard trees, forests, etc. and found that they are notably cooler than other types of terrain.
But which other types of terrain, and are the measurements from above or below? I mean, sure, compared to other typical urban and suburban terrains, they're great. But a closed canopy, or anything else that provides full shade while still allowing warm air to rise, is a huge help for lowering surface temperature.

There's the confounding effect that some trees (and some other plants( sweat isoprene was well as transpiring.

I know the effect is more than just shade, because studies have compared tree shade to, say, building shade and the trees are cooler.
Hoo-boy! Those sound like difficult comparisons. Do you have links handy?

But it's so dramatic that you can feel the difference just walking from the yard to the field or road.
That's what I was wondering: whether you were allows to wander around in the neighbors' fields.


Now it makes me wonder if the trick still works with dryland trees like manzanita, which try to hold onto their water.
Well, being under a stand of acacia trees was better than being out under the tropical sun. :) But I can't tell you by how much.

[mallorys_camera]

Extremely cool.

[rebeccmeister]

Every once and a while I get to catch my breath to the point where I can step back and remember that!

[twoeleven]

Having spent many years being a student playing with dodgy set-ups, we did appreciate the TAs helping get them working. 'course, those were upper level chem classes, where we got to play with powerful lasers and frozen argon, which are much cooler toys... once the apparatus was working.