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Winter Delineation

Swamp Stomp

Volume 18, Issue 49

As I write this, a few states are already covered in snow. This makes any field work very difficult. Heck, driving to the office could be a challenge. Kind of makes that whole global warming thing sound pretty good right about now.

We can’t stop work and wait for spring though. We have to get some field work done! The problem is that we have to balance responsible science with paying the bills. We cannot just lay everyone off when there is snow on the ground.

I have worked in the northern part of the country for many a winter. As a result, I have developed some tips and tricks for conducting wetland delineations in less than ideal conditions. I thought I would share a few with you while you wait for the snow plows to show up.

The first and foremost important item is do not take pictures of the snow and send it to the Corps. You are going to have to wait until you can see bare ground. Most Corps Districts will not even accept the reports if there are snow covered pictures. You will need to let your clients know that there will be a follow–up site visit to finish up the field work when the snow melts.

Now, if the snow is many feet deep, you may still be stuck in the office. First, there is a safety issue and second, there is a matter of really being able to accomplish anything when the snow is that thick. The safety issue should not be overlooked. Under any circumstances, do not venture into the field alone. There are just too many hazards out there that a cell phone cannot help you with. Hypothermia is one of the bigger hazards you may face. Keep an eye on each other.

If you can navigate through the snow safely, you should be able to do a tree survey. The trees can be identified in the winter by twigs, bark, and buds. To be frank, this is a better way to identify them anyway. The leaves can be misleading. This is especially true with the red oaks. The buds are critical to a positive identification of these tricky trees.

Saplings and shrubs will also persist throughout the winter months. Many of these are either facultative wet (FACW) or facultative up (FACU). These can be a great help with wetland determinations.

The herbaceous species will most likely be absent. However, there are some species that persist in the non-growing season. These perennial species often die back to the root, but the vegetative parts remain. Cattails and soft rush are good examples of this. Species like skunk cabbage also die back to the bulb leaving a little leaf ball right below the ground surface in the subnivian zone. This is the space between the snow and ground surface.

If you do encounter herbaceous species in the winter, I would suggest limiting the inventory to only perennials. You may find remnants of annuals in the winter. However, the problem with annuals is that they are highly variable and may be responding to a seasonal or climatic change in the hydroperiod. This may not be typical for the site overall. So if you are able to identify them (to species), make a note and keep an eye on the site when the snow melts.

Hydrology is going to be a tough one. Most of the indicators will either be buried or otherwise be altered due to being frozen. However, there are a few to keep an eye out for.

Obviously, if you see standing water you have a positive indicator of hydrology. Be careful not to include a frozen puddle that may only be there temporarily. Since the evaporation rate is so low in the winter, that area could easily be a false positive. Look for type “C” soil indicators as a backup if you really want to call the puddle a potential wetland. Oxidized rhizospheres would be great to find.

Last, but not least, are the soil indicators. Believe it or not, most of these will persist in the non-growing season. Even the rhizospheres will remain when the soil is frozen.

If the soil is frozen solid, you may have more of a logistical issue extracting a sample than any other issue. There are special devices made to help you with this. The slide hammer attachment works well on a tube sampler, but be prepared to totally destroy the sampler by the time you are done. There are some other clever devices out there that may help you. A little research may be necessary. Your trusty shovel will also work in frozen soil. No need to go to the gym on that day though.

I would recommend that you take a picture of the soil in its frozen state and identify any hydric indicators. Then take the sample to your nice warm truck and see what you see when it thaws out. Note any change in soil color as it warms. My experience is that the frozen soil looks brighter in color and may give you a false negative until it melts.

The Corps may still have issues with any work done with snow cover. Please check with your local Corps field office to see if they have any restrictions. Even if they do, you still may be able to get a jump start on the site and be ready to finish it quickly in the spring. For those of you WAY up north I think that is sometime in July. You will have to hurry before that first Labor Day snow storm!

Have a great week. Stay warm and stay safe.


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