Laci M. Gerhart Barley

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Dendrochronology with K-State’s GROW Program

Checking out a successful core!

Checking out a successful core!

As part of our broader impacts for the Continental N grant, we decided to participate in K-State’s Girls Researching Our World (GROW) program. GROW is run by the K-State Office for the Advancement of Women in Science and Engineering (KAWSE) and introduces regional middle school girls to various STEM fields through one-day workshops and summer camps.

Our session focused on introducing the girls to dendrochronology, including sampling trees, processing cores, and measuring/graphing ring widths.

Allison Walker and I took our GROW girls across campus to identify and core trees, and measure their height and diameter.

Allison and I had a great time, and the girls (and their camp mentors!) enjoyed coring trees and learning about dendrochronology! The weather even cooperated, which is impressive in Kansas.

We got a number of really good cores – many reaching all the way to the center of the pines we chose!

The sampling the GROW students performed is actually identical to the protocol we use for the Continental N sampling, and these cores would have made excellent additions to the Continental N dataset, if they hadn’t been landscaped trees on campus…

Instead, we let the girls take their cores home to show their families.

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Continental N Rises Again!

At least until June 12th, no one will be telling me I’m not in Kansas anymore, because I’m back in Kansas!

Kendra and I were successful with our small grant proposal to NSF for the wood stable nitrogen isotope project (nicknamed ‘Continental N’), which means that we can now actually analyze all those samples Emily and I collected over spring break! I got back to the Paleoenvironmental Lab on May 11th to get the ball rolling and tie up all the loose ends.

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There were a lot of loose ends

Goals:
1) Weigh all the backlogged samples for analysis: All the spring break cores (and others that were mailed in over the last year) have been processed and split. Now we need to weigh out the appropriate amount of tissue (~30 mg) and wrap it in tin for the mass spectrometer to burn up.

2) Herd up the stragglers: there are still a few sites that need to be sampled. And a few that need to be re-sampled because the initial cores we collected were too short for our purposes.

3) The analytical questions: in the grant, we also wrote in a couple strategies for testing analytical fidelity in wood nitrogen measurements. These are nicknamed the replication tests.

So, two weeks in, where do we stand?

Goal 1: Weigh the backlog

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This empty shelf makes me very happy

DONE! With the help of Allison Walker (new undergrad in the lab) and Kevin Courtois (whose wife is a post-doc with Kendra), we got through the ENTIRE BACKLOG of to-be-weighed samples in half the expected time. I am absolutely ecstatic about the progress on this front. There will be more to weigh as we process incoming samples, but keeping up is much easier when you don’t have ~20 sites worth of trees already waiting.

Today, I mailed over 2,000 samples to the University of New Mexico’s stable isotope facility. We’ll hopefully start getting data back on these sites before I get back to Hawai’i. My R code is ready and waiting πŸ™‚

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Good luck, little samples!

Goal 2: Herd the stragglers

We’re making impressive progress on this front, too. 0522151436We have four sites that have been sampled and mailed to us and are awaiting processing: Hoh Forest (Washington), Grand Tetons (Wyoming), Salmon River (Oregon), and Wedington Gap (Arkansas). We also have colleagues sampling in Illinois, New York, Utah, and Nevada in the next week. I’m working on permitting for Pennsylvania, and we’re waiting to hear back from colleagues on a couple other locations, but we’re nearing the end of our sampling stage.

Our completion of the backlog means I can devote my entire attention to processing these cores and getting them mailed off before I leave Kansas. For now, they are drying in the oven, but after Memorial Day, I’ll start cranking through them.

Goal 3: The replication tests

We’re also planning to test the replicability of wood nitrogen measurements by sending homogenized, ground sawdust samples to various isotope labs across the U.S. and Europe and assessing the fidelity between the measurements. Currently, there are neither formal standards for wood nitrogen analysis, nor a standardized equipment protocol. We plan to use these tests and the in-house protocols to develop recommendations for standardizing wood N analysis, and potentially petition the National Institute of Standards and Technology (NIST) for a formal wood stable nitrogen isotope standard.

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The replication test wood

Check back here to see how we progress before I head back to Hawai’i!!

Continental N Sampling: New Mexico, Arizona, and Nevada

As a small addendum to the Spring Break sampling that Emily and I completed a couple months ago, I also made plans this weekend to sample in the desert southwest, namely New Mexico, Arizona, and Nevada. This trip had a number of purposes: 1) sample trees for Continental N, 2) drive Anthony and the rest of his stuff out to LA for fieldwork and then flying to Hawaii, and 3) visit the Barley clan in Las Vegas.

Our first site was near the Sevilleta LTER south of Albuquerque. I say ‘near the Sevilleta’ because I was told that getting permits from the Sev is very difficult, so we technically sampled on BLM land near the Cerro Montosa site of the Sevilleta. The trees weren’t very big around, and the chronologies don’t look very long, but if the rings are narrow, we might get some good temporal length out of them. In Albuquerque, we also picked up Anthony’s friend Levi, who is a grad student at UNM. After we leave Nevada, Anthony and Levi will head to the Mojave for some herping fieldwork.

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Our second site was in Kaibab National Forest, just west of Flagstaff, AZ. Anthony and Levi helped me core a ton of nice big ponderosa pines. We also found an alligator juniper (Juniperus deppeana), whose distinctive bark lead to their common name. Unlike the New Mexico site, Kaibab produced nice long chronologies.

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Our third site was Red Rock National Conservation Area just west of Las Vegas. I wasn’t sure I’d be able to sample here on this trip because the permitting became a bit of a snafu. I started the contacting process for this site at the same time as the other two sites, but was bounced around between contacts at the forest service and the BLM. It was unclear who manages the land on which I planned to sample, and once I found the correct contact (which turned out to be Humbolt-Toiyabe National Forest), there was only a week or so left before sampling. Generally, the permitting process takes about a month to get all the signatures and approvals required. At Humbolt-Toiyabe, one of the largest national forests in the country, it can take 6 months to a year. Fortunately, the permit manager at H-T was incredibly understanding and managed to fast-track our permit. I officially got approval on Thursday πŸ˜› This site was also the best of the trip – HUGE pines with nice long chronologies. Eye-balling and guesstimating years looks like these are definitely several hundred years old. They might be the longest chronologies we have yet in the project.

Anthony’s brother, Mike, also came with us to help out. We had a Barley family barbecue the night before, and I did a little tree-coring demonstration on my father in law’s backyard trees. Mike apparently enjoyed it enough to join us for real tree-coring!

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Now that the coring is done, we’ll spend the rest of the weekend hanging out with the Barley clan, doing a little gambling on the strip, a little sunbathing by the pool, and a little relaxing before Anthony and Levi head to the Mojave to look for gila monsters and I head back to Manhattan!

Spring Break Tree Samples Processed!

It took two months, but I can now finally say that the entire batch of tree samples that Emily and I collected over spring break are now processed and ready for data analysis!

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The final haul of samples, processed and ready for the next step in nitrogen analysis!

In the above picture, each stack represents one sampling location. For reference, the shortest stack in the front right/centerish is South Carolina, and is 5 trays. The tallest stack in the back is Texas (apparently, everything really is bigger there) and is 16 trays. Each tray holds ~80 rings. Some of the Alabama samples ended up in bags because I ran out of trays. In total, we have 13 sites, producing 124 usable cores, totaling ~9,000 rings. While we sampled 130 cores, a few are unusable due to sap stain fungus (see below), rings so faint or narrow as to make splitting unnecessarily difficult (this is why we sampled extra at each site), or ‘crumbly’ cores (which disintegrate after drying).

Individual rings of Juniperus virginiana. Each ring gets its own well in the tray. Notice the variation in color, even within a single ring.

Individual rings of Juniperus virginiana. Each ring gets its own well in the tray. Notice the variation in color, even within a single ring.

For now, the rings are hanging out, each in their own little well. Some of them will be loaded for analysis (see ‘Next Steps’ section), and others will be archived for future research, or as a back-up if any of our isotope analyses go awry. The picture above is of Juniperus virginiana rings from Nebraska.

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Summary of Sampling Locations

To the left, you can see the breakdown for sampled genera and chronology ages at each of the sampled sites. For example, in Alabama, we sampled individuals from Pinus, Quercus,Β and Tsuga. While all the pines were Pinus taeda (loblolly), and all theΒ Tsuga were eastern hemlock (Tsuga canadensis), the oaks included Quercus alba (white oak) and Quercus montana (chestnut oak). Collectively, these trees ranged in age from 60 years old (a Tsuga individual) to 130 years old (also a Tsuga), with the pines and oaks somewhere in the middle.

As is common in dendro work, Pinus and Quercus are fairly ubiquitous, while other genera are less common –Β such as Juglans (walnut) and Liquidambar (sweetgum) which are each represented by a single individual.

The only real problems here are the sites that have short chronologies. South Carolina is the worst of these, with a maximum length of only 29 years. This stand contained good sized trees (diameters of 45-50 cm), but the rings were incredibly wide. Nice growing habitat for Pinus, bad sampling location for me. I’ve been in touch with our contact there in the hopes of finding an older stand and re-sampling.

Less severe, but still awfully short are Tennessee (max 40 years), Nebraska (max 57 years) and Arkansas (max 59 years). We set a (somewhat arbitrary) minimum for usable cores at 60 years. Since our goal is to get at long term ecosystem nitrogen cycling, the longer the core the better. Less than 30 years (like South Carolina) is virtually useless for our purposes (although could still be used for site or species mean values, just not temporal trends). Nebraska and Arkansas may be able to squeak by our cutoff. Tennessee is in a bit of a gray area. As with South Carolina, I will get in touch with our contacts and see if there are known stands of older trees. Again, each of these contained relatively large trees (in some cases pushing 70 cm diameters), but just had large growth rings, and therefore short temporal representation. This will make it difficult to identify older stands without coring a few trees there to see the rings.

It’s also worth noting the different types of cores you get, depending on how you drilled the corer into the tree. There are three ways coring can go:

1) You don’t get to the center of the tree. This can happen if the radius of the tree (distance from bark to pith) is longer than your corer, if the center of the tree is rotted out (as we ran into with many of the Quercus), or if the resistance of the wood to the corer is such that you can’t drill far enough in to reach it. This last can be common in hardwoods, particularly when you have my upper body strength (or lack thereof) and are coring 130 trees in a week….

When this happens, the resulting cores show little or no ring distortion and no central ring.

2) You get far enough into the tree to pass the center, but you don’t actually hit it. This usually happens because you have a long enough corer, and you have the muscular fortitude to get it in, but you cored a little off center. Trees are rarely perfect circles, so this is usually the most common occurrence. Generally speaking, passing the center is considered ‘hitting the center’. You may miss a few years (depending on how far off the mark you were), but you get the bulk of the chronology, and you have a close approximation of the age of the tree.

When this happens, the rings nearest the center show a strong distortion towards the center. You can easily see where the rings start to repeat.

3) You hit the true center, the once-was-a-little-baby-sapling heart of your mighty oak (or pine, you know, whatever).

This results in a core that not only has minimal ring distortion, but also contains the pith of the tree. Now you have undistorted ring width measurements, and the full chronology of the tree’s life, including it’s exact age.

Our sampling fell about equally into the first and second categories, but we did also get five direct center hits (three Juniperus from Nebraska, and two Pinus from South Dakota)! I was very proud of this, even though it involved no real skill on my part and was mostly due to random chance and the law of large numbers.

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And now here are some other cool things from the samples:

1) Sap stain fungus on one of the Georgia oaks. It is pictured next to a healthy oak for comparison. Sap stain fungus (as the name implies) does not seem to permanently impair the tree, but the fungal spores stain the wood a lovely blue color.

Healthy oak (top), and oak infected with sap stain fungus (bottom). Both are Quercus phellos from Arkansas

Healthy oak (top), and oak infected with sap stain fungus (bottom). Both are Quercus phellos from Arkansas

2) I know that eastern redcedar (Juniperus virginiana) is wreaking all sorts of havoc as an invasive species throughout the midwest. But it sure does make for a beautiful core. Reminds me of raspberry-lemon sorbet (random, I know). It also smells wonderful. Despite not *actually* being a cedar,Β Juniperus virginiana is often used to make cedar chests. Growing up, we also used redcedar chips in our dog’s bedding to ward off fleas. My two favorite smells growing up were the cedar chips, and the Pine-Sol my Mom used in our laundry (I was a weird kid, ok?). Not surprisingly, I love the smell of the pine cores too.

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Next Steps

Once we get a green light from the isotope lab, I’ll begin loading our 9,000 rings into tin capsules for isotope analysis. This will take some time, as will the actual analysis, so I’m hoping to get started on it right away.

We also still have samples from other sites that have been mailed to us. While I’m waiting to hear back from the isotope lab, I’ll continue splitting these samples, which are from Ohio, Alaska, and Wyoming.

Additionally, Emily and I are still working on filling in the remaining states. Emily will be sampling in Illinois at the end of the month, and I will be taking a road trip through the southwest and coming back with cores from New Mexico, Arizona, and (hopefully) Nevada. Permitting in Nevada is becoming a bit of a snafu, but hopefully will be worked out by the time I get there.

Check back here for more details as we work through the data and obtain new samples!

Continental N Day 8: South Dakota, Nebraska, and HOME

Screen Shot 2014-03-22 at 8.44.33 AMStates Sampled: Texas, Louisiana, Arkansas, Mississippi, Alabama, Georgia, South Carolina, North Carolina, Tennessee, Missouri, Iowa, North Dakota, South Dakota, Nebraska
Trees Cored: 130
Total Mileage: ~5350 (or ~$650 in gas)
Total In-Car Hours: ~80

I managed to get Google Maps to track our whole trip πŸ™‚

Site 13: Wind Cave National Park, South Dakota
The South Dakota site was much more cooperative than it’s neighbor to the north…. We had to hike over a hill and down to the stand, which was a nice little exercise break after being in the car so long. Also, the stand was all Pinus ponderosa. I’m starting to understand why everyone loves Pinus – it’s such an agreeable genus. It’s super easy to core, super easy to process later in the lab (because it produces really clear rings), and smells nice. What’s not to love? In fact, I got a couple cores that went nearly the full cross-section of the tree. This is not generally necessary for isotope work (at least with carbon or oxygen), but nitrogen requires so much tissue that being able to ‘double up’ on the amount we take with one core might help us get higher resolution in the analysis.

We were also visited by some curious deer while coring. There was a small herd of bison on the next hill, but they didn’t come any nearer to us.

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Site 14: Cedar Point Biological Station, Nebraska
Unlike Pinus, the Juniperus genus is decidedly *not* agreeable. This site consisted mostly of eastern red cedar (Juniperus virginiana), which has low gnarly branches (that you have to crawl between) and has trouble with producing crumbly cores, which get stuck in the corer. Normally, a core you extract is all in one piece (or maybe two), and slides out fairly easily. If it’s broken in numerous places, however, the pieces push against each other, kind of like a pile-up of cars on the highway, and jam up inside the corer. This is the problem for which our Iowa fish hatchery friend created the tool (it still needs a name). We had to use it in Nebraska to remove a couple of stuck cores from the corers and it works *wonderfully* Even with the trouble, we got ten good cores, and then headed back towards Manhattan!

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Final Thoughts
Overall, I think the trip was a huge success. We stayed ahead of schedule almost the entire trip, and got back to Manhattan a half-day ahead of my estimation. With only one site causing major problems, we brought back 130 samples from 13 different states. Considering we had seven states represented before this trip, we managed to nearly TRIPLE our sampling spread. I’m not ready to totally scrap on North Dakota yet – I’ll get in touch with the park biologist on Monday and see what our options are. If we can’t find any usable trees, we may have to remove ND from the analysis. But, I haven’t given up hope yet πŸ™‚

I have never been so happy to see this sign. I’m going to sleep in all weekend, maybe go for a run or a hike, and not spend a SINGLE SECOND in a car πŸ˜€

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Check back here for more details on future sampling, and processing/analysis of the Spring Break cores!

Continental N Day 7: North Dakota

Screen Shot 2014-03-19 at 10.17.30 PMStates Sampled: Texas, Louisiana, Arkansas, Mississippi, Alabama, Georgia, South Carolina, North Carolina, Tennessee, Missouri, Iowa, North Dakota
Trees Cored: 110
Total Mileage: ~4700
Total In-Car Hours: ~69

I’m reusing yesterday’s map because Google Maps is now saying our route is too large to map. Oh, Google – you’re SO FUNNY :-/
Just pretend like that blue line stretches northwest from Minneapolis up to the southwestern corner of North Dakota, and then down to the southwestern corner of South Dakota. I know North Dakota isn’t even shown on there, but just imagine it – you know where it is.

The weather has been perfectly cooperative. We hit some dense fog early in the drive, but we’ve had no snow, no rain, and clear roads.

Site 12: Theodore Roosevelt National Park, North Dakota
So, I’m amazed we made it this far without hitting an real problems. We managed to avoid the weather issues, but ran into something more problematic. Basically, the site we chose (and perhaps ND in general) may not have any usable trees for this project. Specifically, 1) North Dakota doesn’t have a lot of trees period, which I already knew (see forest cover map below). Kansas also doesn’t have a lot of trees and we managed to find some here…. 2) Most of the trees that do exist were planted for winbreaks or property markers, and since we can only use naturally occurring trees, we are even more limited. Again, this I already knew, which is why I chose a national park which would have plenty of naturally occurring trees. 3) The naturally occurring trees are all shrubby and small, with main trunks that are ~10-20 cm in diameter. This is far too small to provide the chronology length we need. And 4) at the specific site I chose, even the shrubby trees were at the bottom of a 30-foot cliff face. We couldn’t have gotten to them even if they were perfect trees.

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Forest cover map

The part relating specifically to the site choice is at least partially my fault. If our needs were clear, it should have been obvious to the park biologist I was working with that this site wouldn’t work. We can’t climb down a cliff face into the @$!^#* badlands to sample trees. I also apparently wasn’t clear about the stature of trees we need. Multi-stemmed, shrubby trees with small trunk diameters are useless for this project. The real problem is I’m not convinced that anything better exists there. I’ll have to get in touch with the biologist and see if there are any other potential sites that would be adequate.

I’ll be honest – driving 13 hours today and having nothing to show for it is excessively irksome.

The only upside is that the Dakotas are beautiful. Emily and I had been missing the great plains – the forests and mountains in the southeast were beautiful, but can be a little claustrophobic. I love the site of rolling grassy hills as far as they eye can see. And all that sky! Also, I love midwestern roadside attractions (New Salem Sue, anyone?)

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The other upside was that we had our first opportunity to do a little site seeing. This also means we made it down to the South Dakota site at Wind Cave National Park. We’ll sample there first thing in the morning, then head down to Nebraska, then HOME.

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Continental N Day 6: Missouri and Iowa

Screen Shot 2014-03-19 at 10.17.30 PMStates Sampled: Texas, Louisiana, Arkansas, Mississippi, Alabama, Georgia, South Carolina, North Carolina, Tennessee, Missouri, Iowa
Trees Cored: 110
Total Mileage: ~3800
Total In-Car Hours: ~56

Today was full of all sorts of interesting developments. First – I found the sunglasses I lost somewhere around Mississippi! We stopped at McDonald’s for lunch and (klutz that I am), I dropped a french fry between the seat and the center console and when I looked down to pick it up, it was sitting on top of my sunglasses. Thanks, renegade french fry!

Anyway, the other fun developments are actually sampling related πŸ˜€

Site 10: Ashland Research Area, Missouri
Our first sampling site today was a University of Missouri research station. Not only did I spend the night in Columbia, I voluntarily set foot on Mizzou property. Forunately, Kevin Hossman (who works at the station and met us at the sampling site) was super cool πŸ˜€ We had some more trouble with the oaks having rotted centers, but I think we got samples long enough for use. We ran into bigger trouble with the extractors – the oaks are hard enough that the cores can be difficult to remove and we may or may not have bent a couple of the extractors trying to insert them into the corers. They’re still usable, but a little wonky.

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Site 11: Big Springs Fish Hatchery, Iowa
This site was already the lab favorite. All the other sites are places you would expect – national forests, university research stations, etc – so a fish hatchery is clearly the oddball… The sampling went about as well as everywhere else has gone – we had a bit of trouble with sticky cores, and rotted centers. In fact, I got another core stuck inside the corer (remember, we’re already down a corer from getting a core stuck back in Arkansas). I expressed my frustration with this problem to Gary Siegwarth, the hatchery biologist. Not only did he get both cores out of the corers (although sacrificing the cores themselves was unavoidable), but he also made us a tool for removing stuck cores from the corers! He welded a narrow metal rod to a flat metal base – the rod just fits inside the corer and can be pushed down against the broad base until the core is pushed out the wider back end of the corer. Simple, efficient, ingenious! I told him this will be a staple of PaleoLab field supplies – I can’t believe such a thing didn’t already exist. Gary should totally patent it.
Gary also showed us around the hatchery. Each of the tunnel-like things pictured below holds up to 10,000 trout, which are used to stock rivers throughout Iowa. We also had a four-legged assistant – the hatchery puppy, a 9-month-old chocolate lab named Woody. Emily and I were hard pressed to not bring him home with us πŸ˜€

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So, what next?
I was still debating the northern loop because of the weather. Today, I called each of the three remaining sites (the Dakotas and Nebraska) to check on the situation. All three of the station biologists assured me there was minimal (if any) snow, that all roads were clear, and that sampling would still be totally doable. So tonight, we are relaxing in Minneapolis – three hours ahead of schedule. Our plan is to power through the rest of the sites – sampling in North Dakota tomorrow, then South Dakota and Nebraska on Friday, and (barring severe tiredness) heading home Friday evening after the Nebraska sampling. We’ll get in late, but it will be worth a final 12-hour day to sleep in our own beds.
On the drive to Minneapolis, we saw a beautiful snowy sunset, and twice passed a bald eagle dining on some roadside carrion. We got a blurry picture the second time…

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Also, there was a patch of snow at the hatchery site in Iowa, where some of the fall leaves had stuck and were melting. I thought they were pretty πŸ™‚

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