Interior Alaska science fair judging

April 16, 2013 by · Leave a Comment
Filed under: Outreach 

Jessie Young was a judge for the Interior Alaska science fair in Fairbanks. She was part of a group that was tasked with judging girls’ posters and helping determine which projects should receive an award funded by the Association for Women in Science and the Alaska EPSCoR program. Here is a link to a spotlight story for IARC:

It’s springtime…. almost

April 16, 2013 by · Leave a Comment
Filed under: CPCRW 

The leaves are not even close to coming out, but our field crew is out every week now. Bob Bolton is measuring snow melt, and Jessie Cable (now Jessie Young) has been busy installing TDR probes and band dendrometers in trees. The TDR probes are used to measure tree water content and the band dendrometers are used to measure tree growth in girth.

We already have several datapoints on tree water content and luckily, they’re still dry (25%). But, that won’t last long. Soon the birch trees will suck up a bunch of water and increase their water content to nearly 120%!

The week after we put the dendrometers on the trees, it appears that they shrunk by 0.5 to 1 cm! That’s a lot. We had to tighten all the bands again. We feel lucky to have “busted” these secret trees as they shrink and swell with the temperature and moisture.

Soon our field work will be in full swing, with more TDR and dendrometer measurements. We’ll continue with the stable isotope sample collection and the water stress measurements. We’re also adding a bunch of stuff to our plate this summer, including evaporation, cavitation, and LAI measurements. Should be fun! With the help of Patrick Ealy and Sammy Dempster, our days won’t be too long.

More to come….

Water, water, water… in the trees

August 27, 2012 by · Leave a Comment
Filed under: CPCRW, Field Work 

One of the easiest and coolest measurements I made this year is tree water content. I applied a tool that is normally used for soils (TDR or time domain reflectometry) to trees! This website has some excellent blah blah blah on the topic:

Basically, the readout I get from the instrument isn’t water content. I have to convert the data through calibration. How might we convert a waveform to water content? This is a really long process. We cut a birch tree down when it was at its wettest state (in early to mid May). We cut this tree into relatively uniform “cookies” about 6 inches long, and we installed probes into them (the exact way the probes were installed into the trees in the field). These probes are where we attach the reader cables for the TDR instrument. Every week or two, I made a TDR measurement on each wood cookie and I weighed it as well. The wood smelled terrible. This was done over several months as the blocks of wood dried out. When the wood was dry, I measured the volume of each wood chunk by immersing it in water (volume displacement). The weight loss of the wood over time was converted to volume of water lost. This allowed me to plot data from the TDR waveform vs. the volumetric water content over time, and voila! I am able to convert field TDR data to water content values.

The cables are attached to the probes or rods in the trees. The TDR instrument and a battery are in my backpack, and the TDR instrument talks to the laptop I’m holding. Once the cables are hooked up to the tree, I tell the TDR to make a reading.

This is a picture of the cables attached to the probes in the tree.


Autumn has arrived, and more water potential measurements

August 24, 2012 by · Leave a Comment
Filed under: CPCRW, Field Work 

It’s already August and autumn is setting in at the watershed. We can see the colors change at small and large scales.

But, the plants are still active, so I’m still out measuring them every 10 days or so. As I mentioned before, one measurement I make pretty regularly is plant moisture stress. This measurement tells us about the water demand of a plant. This measurement integrates a lot of information (see for a good description. Smaller numbers (more negative numbers) means that the water demand or water stress of a plant is fairly high. The water stress of a plant shows diurnal and seasonal variation, and there is variation between species. I do these measurements on black spruce and on birch trees. The spruce tend to be more stressed than the birch trees.

Step 1: Get a branch down.

Step 2: Get the pressure chamber off the four wheeler and set it up.

Step 3: Cut a stem and put it in the holder so that the cut part is facing you, and then crank the holder onto the chamber.

Step 4: Turn on the compressed gas, get out the magnifying glass, hunch over it and wait for the stem to change color (so that it looks wet). When the color changes, the pressure in the chamber and the pressure in the plant have been equalized. Read the pressure on the gauge (15 Bars in this case).

If you see bubbles of water coming out of the stem, you waited too long to take the reading and you have to start over with another stem.

Summer field work in full effect

July 19, 2012 by · Leave a Comment
Filed under: CPCRW, Field Work 

I can’t believe it’s already mid-July! The mosquitoes are still out and biting my face when I’m trying to concentrate on measuring the trees. The constant buzz can be unnerving after a while, and it’s unfair when they fly up my nose. We’ve had good luck with the weather. Summers in the watershed are definitely beautiful! We also haven’t had any bear encounters but we know they’re out there. Footprints in the mud give them away.

Despite the mosquito – nostril interactions, it’s been a productive summer of measuring trees.  One of the five measurements we make is water potential, which indicates the degree to which plants are stressed by not having enough water available.  I use a pressure chamber, which I can describe in more detail later. Since the birch trees are tall and pruning poles are hard to get to the research site, I use a 20 gauge shotgun to shoot branches down.  My aim has gotten pretty good as the summer has progressed. I’m 5 for 5 at each site (5 rounds for 5 trees)! I used to use 7 or 8, but I’ve honed in my skills.

Using a gun in the field as a plant ecophysiology “tool” requires coordination between myself and our field technician, Mark. We are always concerned about safety – as Mark collects tree and soil cores for water isotope analysis, I head in the opposite direction to shoot down branches. With my bright pink headphones on to protect my ears from the gunshots, I can’t hear a thing.

Starting a new outreach project at the UAF botanical garden

April 24, 2012 by · Leave a Comment
Filed under: Outreach 

The Children’s Garden is part of the botanical garden at UAF.

We are helping them run some sap flux sensors they installed into a choke cherry tree. They put sensors on four branches of different sizes. The system was just turned on a couple of weeks ago, so we will be downloading the data soon to show you what this tree may or may not be doing right before bud burst. Here are some photos of the sap flux setup and the gazebo where the data are being collected.

Sap flux installation

April 23, 2012 by · Leave a Comment
Filed under: CPCRW, Field Work 

Sap flux probes in a birch tree

Wiring the datalogger for the new sap flux sensors.

Photos of field prep

April 23, 2012 by · Leave a Comment
Filed under: CPCRW, Field Work 

Loaded up the snowmachine and sled with gear

Had to tie everything down with old thermocouple wire. Forgot straps!

“Um, doc, my plant is turning yellow and has spots. Can you help it?”

April 23, 2012 by · Leave a Comment
Filed under: CPCRW, Field Work 

The new field season brings some anxiety as we scramble to get materials together for the coming summer of field work. The anxiety takes hold because we are trying to “catch” the trees sucking up the spring snowmelt water before their leaves come out.  Anyone living in Fairbanks knows that the leaves appear around the first week of May. We’re all excited to see some green on the hillsides after a long grey winter and brown spring.  Who would have thought that racing trees would be stressful? They’re so secretive about their pre-summer activities that I need to stick probes in them to figure out what they’re doing and why.

The scramble to accumulate materials for field work and probe building can be hard in Fairbanks because there aren’t a lot of places we can get some of things we need.  I tend to go to the obvious places like Radio Shack or Brown’s Electric. But, I also hit up Michaels, JoAnne’s, or the dreaded Wal-Mart. I’m often asked what I’ll be using a particular thing for, and depending on the day, I either talk about it, or I smile and politely back out of the conversation. It really depends on the time crunch I’m under.  I start by saying that I’m building sensors.  When they ask for what, I say that I’m putting them in plants to measure their water use. That’s when I get the response “oh! I love plants. But, tell me, what does it mean when a plant gets little spots on it and turns brown? An aspen in my yard hasn’t put on leaves in years and it’s turning a weird color.” Well, the lack of leaves tipped me off that the plant is probably dead, but I have to smile because the exchange seems like something that would occur between a doctor and a non-patient at a golf course… “uh, doc, I have this rash…”. I smile and suggest that the tree has passed into the world of firewood.

Then it comes time to make the sensors.  Lab time is interesting because I end up in my own head for hours and hours. Doing repetitive activities lets the mind drift.  It’s almost meditative and my thoughts turn to funny things. Today, I’m soldering wires (a stupid word – it should be spelled phonetically, as sautering).  Soldering irons have to be cleaned off periodically because they accumulate solder on the tip and get gunky. Cleaning just entails smearing the hot tip on a wet sponge. The funny part is that the solder is hard to get off so I have to keep rolling the iron around in the sponge to get the stuff off. It makes me feel like I’m trying to wipe a booger off a robot finger.

Off to buy super glue, Styrofoam balls, duct tape, sheets of foil bubble wrap, deep cycle marine batteries, and solar panels.

Looking for Summer Undergraduate Research Assistants

April 18, 2012 by · Leave a Comment
Filed under: CPCRW, Field Work, Jobs 

Please pass this along to anybody you feel might work out well for us. Thanks!

Position Descriptions:

The University of Alaska Fairbanks (UAF) International Arctic Research Center (IARC) invites applications for two (2) summer undergraduate research assistants beginning 20 May 2012 as part of the National Science Foundation funded project “Ecohydrology in Permafrost Systems: The Impact of Watershed Heterogeneity on Stream Flow Dynamics and Hydrologic Pathways.” Through a combination of field work, lab work, and modeling, this project aims to explore the role of vegetation and permafrost dynamics on water fluxes/pathways the sub-arctic (discontinuous permafrost), boreal forest ecosystem. One student will focus on hydrology-related processes and the other will focus on ecology-related processes. Students will learn about and participate in most aspects of the research project including collection of field data, downloading and trouble-shooting data loggers, preparation for field activities, examining and processing data, entering data into data base, testing model code, etc. The ecology student will gain skills in plant physiological measurements.

Applicants should have an outstanding undergraduate record. Candidates must be physically capable of field activities including walking long distances with potentially heavy backpacks (~20-30 pounds) and operation of four-wheelers. At a minimum, the students should be able to use ‘office’ software for data visualization and organization. Ideally, the hydrology student should be computationally strong and have some computer programming experience (such as Python, IDL, Matlab). Students must be enrolled as UAF student in minimum of 6 credits with minimum GPA of 2.0 or a newly enrolled student. Students must also possess a valid drivers license.

Work Environment:
This position will be based at the International Arctic Research Center. Field work will be occur at the Caribou-Poker Creeks Research Watershed, located near Chatanika – approximately 45 minutes north-east of Fairbanks. Students should expect to spend 1-3 days each week in the field.

For summer period, students will work 40 hours per week with a salary of $10.00 per hour.

To Apply:
Please submit a resume, cover letter, and contact information for 2 references. Review of applications will begin on 1 May 2012.

Additional Information:

For more information, please contact Bob Bolton ( or Jessie Cable (

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