Teatime For Wetlands

DSC_0546An exciting trend in recent years, is the “citizen science” movement. Scientists invite the public to collaborate on research, and everyone wins: scientists have more data, everyone else becomes engaged (maybe even excited??) about science, and together we grow our knowledge about Nature. I’m a big fan, regularly participating with my students in Project BudBurst (timing of seasonal events in plants) and Frogwatch (amphibian monitoring), and others from time-to-time.

At Barber Creek Wildlife Management Area in in eastern Iowa (Clinton County), I participated as a “citizen scientist” following the protocol of the Teatime for Science. The idea is brilliant in its simplicity: weigh and then shallowly bury tea bags, dig them up after three months, dry them and weigh again. Natural decomposition processes cause the tea to lose weight, with that weight loss being affected by factors in that specific environment. Two different teas are used, a fast decomposer (Green tea) and a slower one (Red tea). Comparing decomposition over time, and in sites around the world, helps us understand this important aspect of the carbon biogeochemical (matter) cycle.

Tea bags as “decomposition detectors” or “global carbon-cycle meters?” EXCELLENT.

DSC_0548Barber Creek is a State Wildlife Management Area, so I contacted the local Department of Natural Resources officer for permission and  he provided useful advice as well (thanks Curt!). The site includes several deeper ponds (likely, old oxbows) near the Wapsipinicon River, bottomland floodplain forest, and several shallow marshes on higher ground (perhaps farmed in the past, or surrounded by farmed ground). One of those isolated marshes is a recent addition, the Bruckman wetland. That habitat seemed easily accessible, and had characteristics similar to two other wetland sites (Brush Creek in Jasper County and Nishna Bend in Shelby County) also used for this tea experiment.

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As I found in my touching tale of deer-aided work at Brush Creek, the transects and holes with buried tea bags may be difficult to relocate after the requisite 90 day period in the field. “But Paul,” you say. “Didn’t you use GPS to locate your holes/bags and also the ends of the transect?” The answer is “No,” because I had no reliable signal (a problem I have also frequently encountered with cell phone coverage in rural Iowa). I used old-fashioned reckoning with landmarks: sketch a diagram lined up with reference points like a nesting platform in the center of the wetland, and a utility pole or building. It’s not ideal, but it works well enough. I was indeed able to find my transect after 90 days.

DSC_0544Unfortunately, hydrology is variable…and the transect was under deep water when I returned. I couldn’t find and dig the individual holes and buried tea bags. In the end, I had to walk away from the site, and “write off” the tea bags and data they represent. The thing is, this the research protocol has a 10-day window during which the bags are relocated and retrieved, and my return visit was near the end of that window of opportunity. So, the bags—what’s left of them—are still out there. This sort of thing happens a lot in research (at least, MY research). For every “Eureka!” I shout, there are 100 grumbles or face-palms. Even with a well-established, user-friendly protocol, difficulties appear. At some of my sites, I found the hole (and marker), but not the buried tea bag. Or, the tea bag was torn (can’t get an accurate weight—write that one off). Or and animal or plant infiltrated the bag; again, discard that one. And on and on.

But I shouldn’t complain. This was a “pilot study;” I wanted to know if I could obtain the tea at all (found an overseas vendor who will ship to USA), find places to work (yes, several), habitat characteristics and specifics, and various other practical considerations. And I learned a lot from this; I am considering doing more of this in the future (with some alterations to the method).

Later today, my BIOL 229 (Ecology) students will submit answers to questions about this experiment. It’s fun to use real-life field work, even if only a small pilot study, in my class. We actually compared decomposition (weight loss of tea) in the two wetland sites and two upland sites. I entered the data into a statistics program (MINITAB) and compared results using Generalized Linear Model (GLM) with associated post-hoc tests. I can’t go into details now (must let the students work out own interpretations!) but here’s a box plot and stats table for you to enjoy. Later I can make a comment and share my interpretation.

Also, next week, I will share some thoughts on what tea decomposition tells us about changing carbon dynamics in wetlands, and why that process—or similar action anywhere on Earth—is so very important. It is the environmental, indeed societal, challenge of our time. Be sure to stop back and hear all about it. Thanks!

Author: Paul Weihe

Associate Professor of Biology at Central College, traditional author (Textbook of Limnology, Cole & Weihe, 5th ed.; Waveland Press), and now...blogger!

4 thoughts on “Teatime For Wetlands”

  1. If there were 4 reps and each rep was a location I think the sample size is too small to make any meaningful conclusions—like you wrote small study. A box plot with 4 values does not represent a distribution of measurements and a relative measure (% of total remaining) also may be inappropriate for statistics. Better to use a scatter plot of each individual as a more accurate representation.

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    1. Hi Herb! Thanks for the thoughtful comments. I actually presented your thoughts to the class…they had already grasped the problem of small sample size. However I didn’t make clear what the box-and-whisker diagram represents: it is combined data for both upland sites (one box) and combined wetland sites (one box). So, they actually represent a larger sample (but…still smaller than I’d like).

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  2. Update for everyone: the data are peculiar, with one wetland site (Nishna) having greater decomposition (less % mass remaining) than the other sites which were fairly similar. I have no idea why!
    Overall, this was activity was valuable as a learning opportunity—students in fact performed well on a test of their interpretation of the data and meaning—and might be worth a follow-up. But the trial should be started earlier in the growing season, have more bags buried, and I must find more effective ways to retrieve (intact, usable) bags. I’m wondering about the wisdom of burying bags in a wetland—simply laying on the bottom of the water (resting on the mud) might be more appropriate?? I’ll keep thinking about this…

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