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| While this may not be one of the most photogenic pictures I have ever taken, it illustrates the point I write about above. This is a wetland and in the winter and parts of spring and fall, you walk through water here. However, on a warm summer day this is dry as a bone as you see here. A property owner could easily say: "What wetland?" |
I often start out with telling my students how wetland
delineators do their jobs and the way I started out in this business back in
the early 1990s. I was a part-time
assistant professor at the Gallup branch campus of the University of New
Mexico, when the Chair (and only full-time staff member) of the biology
department got a call from an owner of an old sawmill just across the border in
Arizona. The sawmill had shut down, but
in the past, they had treated their lumber with arsenic to make treated
lumber. My understanding was that the
soil was contaminated, and they were going to be required to clean things up,
but the site drained into a wetland, and they were either supposed to stay out
of a wetland that was below the site, or only supposed to clean up the wetland
since that was the place where all the arsenic had ended up. Either way, they needed to know the extent of
the wetland and were wondering if there was anyone at the university that could
help them. I was hungry and wanted to
start my own consulting business, so I went for it (the chair was a human
biologist and could not distinguish one plant from another, let alone identify
a wetland). Truthfully, I had never done
it either, did not know what the heck I was doing or what it was about. All I knew was that I was an ecologist, so, I
thought, it must not be very difficult to figure out.
Being at a university I was able to get a hold of the Corps
of Engineers “Wetland Delineation Manual” and I set out to work. It was a very isolated site on the Navajo
Reservation, not too far from Gallup, kind of interesting an abandoned sawmill,
eerie but still neat. I figured that it
would not be very difficult, here we were in the Four Corners, in the Sagebrush
Steppe which can be considered part of the Great Basin Desert or if you are a
splitter it technically can be called the Colorado Plateau (Desert). Whatever you call it, the area is dry, and a
wetland should be darn obvious. Boy was
it ever! That is the nice thing about
working in the desert.
A few years later, after moving to the mid-west and gaining
more experience I became quite the expert wetland delineator. I first lived in Cincinnati and ended up traveling
throughout the U.S. to do delineations. While living in Virginia I traveled all over the eastern U.S. In my blog post that contains my sermon I discuss some of the perils of field work, including being hit by a cottonmouth.
What I had learned during my career as a wetland scientist was that desert ecology and wetland
ecology was not that different. Plants
were under stress. In wetlands plants
had oxygen stress in their roots because of flooded soils, and because of that
could often not take up water unless they had very specific adaptations. Being an arid land physiologist by training
(who could not find a job and thus ended up in consulting), I found that this
was not very different from desert plants who were also often under (drought) stress and
had very specific adaptations to survive.
The issue is that plants only have four major hormones and only one of
those four hormones, ethylene, mediates stress.
I spent a lot of time studying this hormone; in the past it was thought
that is was released as an adaptation to flooding and it helped with fruit
ripening (that’s how we get evenly ripened fruit like bananas on the shelves in
our grocery stores); however, we were able to show in the lab that it also made
plants more tolerant to drought stress. Oh
well, I will leave it at that.
When I started my career as a wetland scientist I learned
that I had to look for three main characteristics in the field: certain plants
that are known to grow in flooded conditions, while other plants absolutely
could not; soils that showed signs of flooding; and landscape features
indicating flooding. We also call this
the three mandatory wetland criteria: vegetation, soils and hydrology. This is what we look for when we examine a
site, we look if it is a wetland or has pockets of wetlands. Over time wetland delineations got easier
and easier to a trained eye, although it was always exciting when you got to a
new area in the country, where you had never delineated before. You got to see new plant species and new soil
types. I was always a bit nervous to start
out in such an area. I usually studied the soil survey of the county to see what kind of soils I may encounter, while in the field I often collected plants to take back with me to my motel room or to my office so I could take my time to identify them.
We sometimes joke that we delineate with our feet; actually,
it is a combination of feet and eyes.
With a bit of experience, you start noticing subtle changes in vegetation
composition, and the consistency of the soil under your feet. The ground might just get a little softer and
at the same time it feels like you just stepped one or two inches lower in elevation. This may be important, for as I described in the beginning of this post, wetlands can be bone dry, especially in the middle of the summer. But, together with a minor vegetation change like
the entrance or disappearance of one specific plant species may be enough to
make you stop and wonder. Now it is time
to examine the soil. Has the soil also
changed when you crossed that subtle boundary you think you perceived in the
field. At first, I would take several soil
samples with a probe or an auger on both sides of the boundary to compare. Once I determine that I may have a soil that
is representative of a wetland soil I may use a shovel to dig a decent soil pit
to get a representative soil description. Subsequently, I determine the boundary of the
entire wetland, flag it and describe it, after which it is ready to be
surveyed. I often survey it with GPS,
although that is not as accurate as a survey done by a licensed survey
crew. After that it is often up to the
engineers, the owner and the developer to decide what to do with or to the
wetland.
One of these days I may write more about wetland plants, wetland soils or the more illusive hydrology. Stay tuned.
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| A wide-angle photo of one of the ponds behind our home. There is still a little water visible in the center of the pond which is 6 feet (1.8 meters) deep in the middle. In winter and early spring the water comes all the way to where I am standing. As you can see, at that time and in early summer these trees stand submerged in water. Species include: black gum, red maple, tupelo and overcup oak. They are what we call wetland species. |
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