I’ve
spent the summer trying to write my dissertation, which means I am full of
angst. The dissertation is simultaneously
extremely high stakes and exceptionally unimportant. I have to come up with a defensible write-up
of the last five years of my life – that’s a lot of pressure. But the dissertation is a big paper about my
tiny area of expertise and the only people that will read my dissertation are
my five committee members (if that). All
these feelings are compounded by academic inferiority complexes: few people
study wetlands and among wetland ecologists condition assessments aren’t sexy. But wait!
I like what I do and think it’s interesting, so here’s my effort to sort
out the point of it all.
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| Assessing Vegetation Plot #945 |
Great
Salt Lake (GSL) wetlands are amazing!
Sometimes they’re salty, sometimes fresh and they go from flooded to
bone dry in unpredictable ways. I get to
study the bad ass plants adapted to life in this harsh and dynamic environment. I’m really excited about those plants! Plus birds – millions of birds that migrate
across continents, stopping in my wetlands to plump up. The focus of my research at USU has been on wetland
water: how do we legally secure water for wetlands and what is the impact of
our water decisions once it gets to the marshes? I study GSL wetlands because I am passionate
about them, they are special to me and I want to help protect them. Scientists are generally discouraged from
using exclamation marks when writing about their research because it seems
un-objective. I disagree with that
advice, but it does point to a valid concern: how do I objectively measure something that my feelings are so subjective
about? Science! Specifically, ecological condition assessments – measuring the ability of a
system to maintain structure and functionality in the face of disturbance [1]. Doesn’t that phrase just suck your enthusiasm
away?
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| One of these wetlands is better than the other - let's use science to figure it out |
As
boring as condition assessments sound, they provide a metaphor for understanding
the academic thing I do because we can compare wetland condition to human
health. Your body has organs with
specific functions: the lungs breathe in oxygen, the heart pushes oxygenated
blood through the body, and the kidneys filter all the blood. Wetlands are also multi-functional: they prevent
flooding, filter pollutants from water, and harbor biodiversity. One wetland function is valued above all
others in the West – the ability to feed and shelter waterfowl, which we call
habitat provisioning. I’m interested in
finding out whether wetland management focused on maximizing waterfowl habitat
has a positive or negative impact on overall wetland condition – you know,
those other functions. In our metaphor
here, does focusing on heart health come at the cost of other organs or does it
make the whole body work better? And the
bad ass plants I mentioned? They are
excellent indicators of condition because they are responsible for providing
many wetland functions and they respond to disturbance [2]. In the absence of humans, wetlands look and work awesome (also called reference condition). As disturbance increases it changes condition for the worse, and disturbance comes from many sources, some quite far away. When a wetland is disturbed, the native stand-forming, wetland species are replaced by fast-growing, stress-tolerant and invasive species. However, the details of disturbance and the nature of plant communities vary and needs to be studied carefully by people like me.
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| Examples of disturbance and their potential impacts. Individual wetlands face a unique group of threats, condition assessments sort out which disturbances matter and what their impact is. |
To figure
out wetland condition I randomly selected 50 emergent GSL wetlands from Brigham City to Salt Lake City, Utah. Why so many? Because ecology is complex and you need a
whole lot of samples in order to make statistically valid inferences about the
processes driving the patterns you see. I
sampled the plant communities in these wetlands over four summers so I could
see what the wetlands looked like for real, not just in wet or dry years. I also gathered data on the water table
patterns, soil chemistry, and physical disturbances, which I used to identify
the factors driving condition in my wetlands. I wish I could elaborate on how much work it was to gather all that data - it took years of my life - but that's not the point.
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| I have visited all of these marshes 9-12 times since 2012. Each is strangely special to me |
I’ve
run into prolonged angst developing a reasonable wetland condition score. We know a lot about how to detect
and diagnose sickness in people, but we know less about wetlands. GSL wetlands face an odd combination of stress:
they don’t get as much water as they need and the water that comes is full
of stuff like fertilizers and water bottles.
When the wetlands are dry they get saltier, and when they’re flooded
there's too little oxygen. Sounds like a
stressful place to live, right? Wetland
life is naturally pretty stressful but we don’t know how stressful it was
before we mucked it up, so it’s difficult to figure out exactly what is our
fault and what is natural. The human
mucking up, or anthropogenic stress, is what we need to know about. And now we manage those wetlands through a system of dikes and canals, creating a bunch of large, shallow
wetland reservoirs (called impoundments) to buffer them against the stress we’ve caused by
diverting all their water away and replacing it with stinky-poo-water. Are we doing the right thing and actually protecting
wetland condition?
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| Impoundments or "duck ponds" are unusual in most of the country |
Hundreds of options are available to characterize condition (see
pgs 108-138 here [3] to get a sense of the possibilities). Ideally, we select attributes that both
measure condition and help diagnose causes of impairment in our specific system through
hypothesis testing. To this end I’ve calculated
numbers to describe the plants present and run statistical tests based on
hypotheses about how wetlands work. I
like to think its like going to a real doctor and verifying a diagnosis through
lab work. But what if I forgot a hypothesis? What if GSL wetlands are so extraordinary
that we need to measure condition here in a completely novel way? That
idea keeps me up at night and suggests data mining might be good: calculating
every conceivable metric of the plant community and using any that has a
correlation, regardless of how much sense it makes. Kind of like going to WebMD to diagnose your
back pain – there are lots of plausible options but they’re not all helpful. But there’s also a middle ground, calculating
traditional condition metrics and few unique, GSL-specific things. I think I’ve finally got it figured out now. Mostly.
The answer to the big question – are we doing good or bad by managing wetlands in impoundments – has been clear since my first analysis but now (900,000,000 lines of code later) I understand the reason why, too. Impounded wetlands are in better condition that unimpounded wetlands, so we’ve been doing a good thing. Impoundment isn’t natural, but it buffers Great Salt Lake wetlands against severe and sustained drought. One of my master’s thesis interviewees told me as much, that they weren’t recreating natural conditions, just doing the best they could to maintain wetlands with the limited water available to them [4].
The answer to the big question – are we doing good or bad by managing wetlands in impoundments – has been clear since my first analysis but now (900,000,000 lines of code later) I understand the reason why, too. Impounded wetlands are in better condition that unimpounded wetlands, so we’ve been doing a good thing. Impoundment isn’t natural, but it buffers Great Salt Lake wetlands against severe and sustained drought. One of my master’s thesis interviewees told me as much, that they weren’t recreating natural conditions, just doing the best they could to maintain wetlands with the limited water available to them [4].
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| This wetland is one of the best, science tells me so. |
My
results are different than other condition assessments because my wetlands are
pretty unique, even though the plant species are quite cosmopolitan. The biggest threats to wetlands in other places
are landscape changes and poor water quality, while in Utah water scarcity is
the biggest threat to wetlands [5].
Changes to water availability along our rivers are so pervasive that
unimpaired reference condition doesn’t exist, which matters because that’s
how you compare condition across wetlands – how different they are from
reference [6]. The GSL wetland condition
score is based on six attributes, each of which responds a little differently
to drought, cows, and other sources of stress.
Wetlands that don’t experience too much stress only have a few species
present (that’s unique), and those I found were native to Utah, found almost strictly
in wetlands, and tended to be long-lived grass-like species. As stress increases more plant species wander
in, species that belong more in dry ecosystems or other continents
(invaders!).
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| Left: Cirsium vulgare - an invasive upland plant that can be found in poor condition sites. Right: Schoenoplectus acutus - a native wetland plant that forms dense stands, found mostly in good and reference wetlands |
Why
does any of this matter? Here we circle
back to my inferiority complexes. How do
I convince anyone to care about my work if they think wetlands and/or condition
assessments are lame? I could go into
the economic values of wetlands ($14,785 per hectare per year) which are
contingent upon being in highest possible condition, but that’s not my thing
[7]. If you live on the Wasatch Front
there’s a clear link to your health: as the wetlands and Lake dry up air
quality problems worsen [5]. Anyone who
cares about me might care that I have results.
But big picture, wetlands and ecological condition matter most in the
context of watersheds. Water connects
all of us to each other to the wetlands, which moderate nearly every point in
the water cycle from high mountain springs to lowland floodplains. Wetlands are the metaphorical sponges
(soaking up flood water and releasing it slowly) and kidneys (filtering out
pollutants) of the watershed, but they only do that work when they are in good
condition [8]. Two-hundred years of
wetland destruction followed by catastrophic floods or dust storms taught us
that. We destroy wetlands more slowly
now, so the work has shifted to protecting and improving the condition of what
we still have. Properly measuring
condition is critical for keeping wetlands do the things they're awesome at.
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| Condition assessment results (left) can be used to identify wetlands that warrant more protection (center) as well as those that could use a little help (right) |
What
should we do about it? Love your
wetlands, visit the marsh, purchase stuff that supports Pittman-Roberts funds,
and don’t over-water your landscaping. I
have some management recommendations, too.
Impoundment is pretty good for wetlands, but should be done carefully:
no need to flood deeper that 40 centimeters and definitely let the wetland dry
out once a summer. Outside of impounded
areas it’s harder to figure out the best strategy, but getting as much area
flooded just a little bit, at least during May and June is important. Oh, and fund my future research! I want to figure out what the heck is going
on with the water quality in wetlands.
Literature Cited
- Karr, J.R., Chu, E.W., 1997. Biological monitoring and assessment: using multi-metric indexes effectively. University of Washington, Seattle, WA.
- U.S. Environmental Protection Agency, 2002. Methods for Evaluating Wetland Condition: UsingVegetation To Assess Environmental Conditions in Wetlands. Office of Water, U.S. Environmental Protection Agency, Washington, DC.
- U.S. Environmental Protection Agency Office of Water Office of Research and Development, 2016. National Wetland Condition Assessment 2011 Technical Report, Washington, DC. Link
- Downard, R., Endter-Wada, J., Kettenring, K., 2014. Adaptive wetland management in an uncertain and changing arid environment. Ecology & Society 19.
- Wurtsbaugh, W., Miller, C., Null, S., Wilcock, P., Hahnenberger, M., Howe, F., 2016. Impacts of waterdevelopment on Great Salt Lake and the Wasatch Front. Watershed Sciences Faculty Publications.
- Davies, S.P., Jackson, S.K., 2006. The biological condition gradient: a descriptive model for interpretingchange in aquatic ecosystems. Ecological Applications 16, 1251-1266. Link
- Costanza, R., d'Arge, R., de Groot, R., Farber, S., Grasso, M., Hannon, B., Limburg, K., Naeem, S., O'Neill, R.V., Paruelo, J., Raskin, R.G., Sutton, P., van den Belt, M., 1997. The valueof the world's ecosystem services and natural capital. Nature 387, 253-260.
- Keddy, P.A., Fraser, L.H., Solomeshch, A.I., Junk, W.J., Campbell, D.R., Arroyo, M.T., Alho, C.J., 2009. Wet and wonderful: the world's largest wetlands are conservation priorities. Bioscience 59, 39-51.
