Archive for the ‘Zak Gezon’ Category

Deflation patches are everywhere! Well, more accurately, they are often on south facing slopes and relatively close to the ice sheet. Ruth, our resident deflation patch expert, has been taking Cohort 4 around to lots of deflation patches so that we can measure how much vegetation is present in and around the patches. Deflation patches are easy to identify- they are areas of exposed rock and loess (sediment deposited by wind) in an otherwise vegetated ground cover, with a ‘scarp’ on the uphill edge of the patch.

deflation patches

deflation patches and their furry friends

Deflation patches expand when wind digs away at the loess and the surface vegetation no longer has anything under it; so, the presence of a scarp, or wind-eroded cliff, can often be the tell-tale sign of a deflation patch.deflationpatch2These patches can vary in size from a few feet to hundreds of feet across. Judging from all of the satellite and airborne imagery that we have attained, the deflation patches have not expanded noticeably in the last 70 years!


Ruth explaining deflation patches- my “Ah ha” moment!

A lot of our work on deflation patches has been to go out to many randomly chosen locations within Ruth’s study areas and simply record what we see (Ruth will later compare these observations to her satellite imagery). So out we all go with Ruth, hiking up and down the rolling hills of Kangerlussuaq with a 0.5 m by 0.5 m PVC quadrant in hand. We lay down the quadrant and estimate a percentage of vegetation cover for that location. Next, Ruth types in a new survey location and the GPS leads us off into the hills again. We have over 100 randomly chosen locations to visit during our stay at Sea Horse Lake.


Ruth and Zak estimating vegetation cover

Since the airborne imagery of this area is fairly recent, and deflation patches expand slowly, we need some other way to determine the age of these patches. Enter lichenometry! Lichens are capable of existing in some of the harshest environments on Earth- out here in Greenland they come in many varieties and colors, but all seem to enjoy growing on rocks. A few characteristics of lichen make them useful for dating: 1. They need the sun to grow and 2. They expand at a predictable rate. By measuring the width of lichen on rocks within the deflation patches, we can determine when the loess that covered them was removed. Ruth, to date, has already measured over 3,000 lichens!


A triumphant Ruth after recording her last ‘percent vegetation cover’ measurement!

Being out here in Kangerlussuaq with Ruth, I was finally able to see the deflation patches and lichen she’s been writing proposals and talking about for the last year- it’s incredible to see everything finally coming together! Cohort 4 has had lots of fun going on deflation patch hikes and estimating vegetation cover during our time at Sea Horse Lake- be sure to check back in and see all the other science we’re doing up here!


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How Many IGERTeers Does It Take To Haul 1,000 Pounds of Water?

When I applied to graduate school, I had my heart set on studying how pesticides bio-accumulate in squid after being carried from one side of Costa Rica to the other via the seasonal trade winds. After many false starts and dead-ends (and almost five years later) the focus of my dissertation is on the effects of altered flowering phenology on plant-pollinator interactions and plant reproduction. To say I changed course would be a major understatement. Would my squid idea have worked out?  Probably not.  Had I done any research into the topic?  Pfft, of course not! It just sounded like a fun idea. So how did I go from a crazy, squid-based research idea to a more interesting, practical, and basic-science oriented question?  Through a lot of trial-and-error and helpful advice from my committee and advisor.  Thanks, guys! But chasing kooky, quixotic ideas and getting pulled back to earth is all part of the graduate school experience. And it’s a healthy experience, I think.  I have to admit it is satisfying to look back and see the progress that I have made, and it is equally satisfying to see the progress that the other members of my cohort have made.

Julia Bradley-Cook teaches us about carbon in soils and the atmosphere near her field sites in Kangerlussuaq, Greenland

Julia Bradley-Cook teaches us about carbon in soils and the atmosphere near her field sites in Kangerlussuaq, Greenland

Julia Bradley-Cook, a friend and fellow IGERTeer, has just wrapped up a field season here in Greenland.  We were lucky enough to spend some time with her in the field before she finished what will likely be the last field season of her dissertation. It was an amazing experience for me because Julia and I are in the same cohort in the Ecology and Evolutionary Biology (EEB) program at Dartmouth, and I have seen her research develop over the past four years through her talks and presentations at Dartmouth. But this was my first time seeing Julia’s science first hand, in the field. And while my research dramatically changed directions (several times) during my first couple years as a graduate student, Julia is literally doing the polar opposite of what she had initially set out to study.


Julia laughs as Ross breathes into the infrared gas analyzer, increasing the CO2 levels.

I clearly remember Julia’s first talk at Dartmouth, in which she proposed studying soil carbon flux in the dry valleys of Antarctica. She went to Antarctica, tried out her ideas, and like most graduate students failed to generate data that would turn into a dissertation.  Sad, but true.  Then she decided to follow a similar line of research in an environment that was better matched to her research question: in the arctic rather than the Antarctic. Julia’s current work focuses on how arctic soil respiration will respond to an increase in precipitation.  She explained to us that the atmosphere contains about 750 gigatons carbon. Soils, on the other hand, have about 3,200 gigatons globally.  That means that soils hold over four times as much carbon as the atmosphere! Mind blowing.  What’s more, about half of all that carbon is in arctic soils, if you include boreal forests.  Climate change models predict that precipitation in Greenland will increase by 15% by 2050 and by 50% by 2100. How are the arctic soils going to respond to this increase in precipitation?  That is one of the main focuses of Julia’s dissertation, and to investigate the question she is adding water to 18 plots, each paired with a control plot, and then measuring soil respiration using an infrared gas analyzer.


Alden takes some soil respiration data!

So far she has been adding 6 liters of water to each plot, which reflects a realistic increase in precipitation over the next 90(ish) years.  Her results have been quite interesting thus far, although some could argue that the results are a bit ambiguous.  So she decided that she needed to take a sledgehammer approach: add an enormous amount of water, and see how soil respiration is affected. That way there would be no ambiguity as to the response to water itself, and then she could use those data to help interpret her more realistic water additions. For the sledgehammer approach, she decided to add 24 liters of water to each plot over the course of a very short period of time and then take soil respiration measurements every ~12 hours over the following few days. 24 liters of water * 18 plots = 432 liters of water total.  Remember that 1 ml of water has a mass of 1 gram, so 432 liters of water has a mass of 432 kilograms.  What’s more, the water needed to be hiked up to her sites from a lake.  Woof.  That’s a lot of work. And it would have been nearly impossible for Julia and her hard working assistant Leehi to have done it by themselves. Luckily, IGERT cohort 4 (later named “Totally Awesome Cohort” by Ross) was there to help!

I practice the spraying technique.  If I do it right, 12 pumps = 1 liter of water!

I practice the spraying technique. If I do it right, 12 pumps = 1 liter of water! photo by Leehi Yona

Once we hiked up to the sites carrying a backpack filled with five gallons of water, we needed to get the water onto the plots.  We used two techniques for this, one slightly higher tech than the other.  The first was to dump the water, one liter at a time, through a colander.  The colander helped to spread the water out as it fell, much like a sprinkler.  The second approach was to use a backpack with a pump-sprayer attached.  I have used similar backpacks before, but this was a new design for me.  Apparently the one we were using is made for firefighters.  I have to say, I feel bad for those firefighters.  The backpack would leak about a third of its water down the back of the wearer, and using the pump spraying was surprisingly draining! But technical difficulties aside, we managed to haul all the water up and apply the treatments to her plots. The next few days were an insane push for Julia to take all of the necessary measurements and prepare for her departure, but she managed to pull it off. Congratulations, Julia, on wrapping up another field season, we can’t wait to see how the data turn out!

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Bombus!”  Kristin sounds the alarm, pointing toward the large buzzing bumblebee attracted to her white baseball cap.  Immediately, Christine, armed at all times with her insect net, springs into action.  I’ve never seen someone run so quickly across the tundra – Christine running after a Bombus is truly an amazing sight.

Christine poses with her ever-present net.

Christine poses with her ever-present net.

“Wham!” Christine’s net hits the ground.  Success again!  Trapped inside her net is a surprisingly large (at least the size of two Hershey kisses) bumblebee, buzzing in anger and confusion.  With no hesitation, Christine expertly slips a vial into the net, taps the bee into the vial, and there – another sample caught!

Ivalu holds one of captured bees while Kristin skeptically looks on.

Ivalu holds one of captured bees while Kristin skeptically looks on.

In Greenland, there are two bumblebee species: Bombus polaris and Bombus hyperboreusB. hyperboreus is a parasitic bee – that is, the queens will take over a B. polaris nest and trick the worker bees, who never realize they aren’t working for their own queen.  Not many people have studied bumblebees in the Arctic, so with each Bombus capture, Christine added valuable information to what we know.  A good reason to celebrate each new sample!

A bumblebee visits Niviarsiaq, the national flower of Greenland.

A bumblebee visits Niviarsiaq, the national flower of Greenland.

From our pollination experts Christine and Zak, we also learned that arctic plants are often pollen limited.  If the flowers are given additional pollen, they are able to produce more seeds.  In order to get more pollen, plants compete for pollinators, putting on showy displays and enticing insects with yummy nectar.  To test just how pollen limited arctic plants are, Christine had us set up a simple experiment using Niviarsiaq (the national flower of Greenland).  On some plants, we tied mesh bags around flowers to exclude pollinators.

Mesh bag placed around Niviarsiaq flowers to exclude pollinators.

Mesh bag placed around Niviarsiaq flowers to exclude pollinators.

On other plants, we added pollen by hand, mimicking the role of a bumblebee.   A third set of plants we identified as controls.  Later this summer, Christine will collect the seedpods from all of the plants and compare how many seeds each plant was able to produce.  If the hypothesis is correct, and the plants are pollen limited, the hand-pollinated plants should be the most successful!

Last year, after living in the tundra for six full weeks, I hadn’t given pollination a thought.  I vaguely remembered seeing what might have been a bumblebee.  This year, however, my perspective has completely changed.  Whenever I hear the frequent buzz of Bombus, my head immediately turns and I think, “Go, Christine, go get it!”  Many thanks, Christine and Zak, for teaching us the art of Bombus-ing!

The Bombus itch spreads -- Alden catches her first bumblebee!

The Bombus itch spreads — Alden catches her first bumblebee!

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Knoxville, Tennessee hosted the 2012 annual meeting of the Entomological Society of America. The theme this year was A Global Society for a Global Science. Many of the sessions highlighted the latest research on how global change will impact insects as pollinators, pests of agricultural and forest systems, and vectors of disease.

Zak Gezon and I presented our research that falls within this theme. Zak shared his results from a study of how collecting bees for scientific studies affects native bee populations.
Zak at his field site

[Zak and his bee net near Gothic, Colorado. Photo credit: Jess Welch]

Pollination biologists collect hundreds of bees every year to count and identify for important studies such as climate impacts on pollinator phenology (more on this in the future from Zak). Given significant concerns about global pollinator decline, it’s necessary to think about how collecting bees for these studies may affect native bee populations. The highly-anticipated results of Zak’s study are good news for scientists, as they suggest so far that the number of bees collected have negligible effects on bee populations.

I shared the Arctic perspective in a symposium titled “Aquatic Entomology as a Measure of Global Changes.”

speaking at the Entomology meeting

[Lauren on stage, talking about insects. Photo credit: Ramsa Chaves-Ulloa.]

The highlight was sharing my latest data on climate effects on mosquito abundance. Turns out, and consistent with local knowledge, a warm and wet spring ups the number of mosquitoes that survive to emerge. I also shared some preliminary data on mosquito fecundity, or how many eggs a female mosquito will lay. With the help of some very tolerant lab assistants, we counted the numbers of eggs in hundreds of mosquitoes collected from Kangerlussuaq this spring.

a female full of eggs

[The maximum number of eggs counted from one mosquito is… 122!]

In addition to sharing science, being at these meetings provides an opportunity to meet and talk with entomologists from around the world.
excited entomologists

[Some very excited entomologists, including Zak Gezon (second from right) and Ramsa Chaves-Ulloa (right) from Dartmouth’s EEB graduate program.]

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