There are two key things to keep in mind
when managing wetlands. First, you are trying to mimic natural wet/dry cycles, while tweaking
them to meet your specific interests. Second, do not force your land to do something that it's not capable of doing. While
it may be possible it will require considerably more inputs extra cost, extra labor, or more
skill to make it happen. As an example, you may decide to allow lower elevations in your
wetland to function as an emergent marsh since lower elevations stay wetter longer. Fighting
this natural tendency to manage these areas as seasonal wetlands will require considerable
effort and will often yield only marginal results. Upper elevations, which are drier, would be
better managed as a seasonal wetland since keeping water on these sites long enough to
develop into an emergent marsh would require artificial pumping. Also don't over manage. There is a
temptation to try and have the wetland look the same every year, which is virtually impossible.
Wetlands are dynamic, and change not only during the year, but also between years. You
may have had wonderful results with an early drawdown of your seasonal wetland last year,
but this year it's raining almost every day. Rather than try and fight the natural wet cycle, shoot for a later drawdown, or change
management to more closely mimic an emergent marsh during this wet year. Drawdown of the water level is the most common
action in trying to mimic the natural wet/dry cycles of wetlands caused by seepage and natural
evaporation. Altering the time and/or speed of the drawdown has a direct impact on the
plant community and the habitat provided. First, it isn't always necessary to artificially drain wetlands in order to provide
high quality habitat. Natural evaporation and seepage even in very tight soils will
provide some fluctuation without artificial drainage. The benefits of this type of natural
drawdown allow different wetland types and plant communities to develop based upon elevations
within the wetland pool. This also reduces the need to add water in the fall to provide
migrating habitatwhich may be especially important for wetlands that lack some form
of artificial flooding capability. Also, don't forget that semi permanent wetlands, emergent
marshes or shrub swamps provide valuable habitat for many wetland wildlife species. If you decide to artificially drain your wetland
pool for seasonal wetland habitat, always drain slowly. A good rule of thumb is to drop
the water level one inch or less a day. The timing of the drawdown will influence
the resulting plant community. In general, you can expect the following: early drawdowns
defined as the first 45 days of the growing season usually yield smartweeds and rice cutgrass.
Mid season drawdowns the second 45 days of the growing season typically result in wild
millets, panic grass and some beggarticks. Late drawdowns which expose soil after the
first 90 days of the growing season mainly produce sprangletop and beggarticks. Plant response will vary depending on the
year as the seedbank, temperatures, and rainfall during the drawdown, influence this response. Spreading the drawdown over the entire growing season provides the greatest variety in plant
response. Always try to stagger drawdowns to increase diversity. Avoid doing the same
thing in the same wetland unit each year in order to better mimic natural weather cycles.
Over time, stable water management tends to yield undesirable results. Also, remember that unless you have the capability
of artificially flooding, artificial drawdowns in the spring almost always result in less
water in the fallsince fall runoff or flooding events are unpredictable. How you achieve reflooding directly impacts
your drawdown strategy. Does the site flood? If it does, how frequently and at what times
of the year does the site receive runoff from adjacent land? When does it occur? Do you
have the ability to pump water on the site? If so, how much pumping can you afford? Do you have the time to service the equipment
and watch over the pumping operation, or do you have someone else who can? If you rely on natural recharge through flooding
or runoff, your drawdown strategy will be tied closely to the site's ability
to consistently gain water in the fall. You may choose to only do partial drawdowns in
most years to assure at least some water for fall migration. You may decide to close all
your water control structures early in the season to ensure capturing any runoff through
the growing season, knowing that it may flood some vegetation deeper than you would prefer. If you have the ability to artificially pump,
understand that it's more complicated than simply adding water. The goal is to still
try and mimic natural cycles, which means increasing water levels slowly and incrementally
from one to three inches a week. You can begin these increases as early as late August and
finish by mid November. Finally, when artificially manipulating water, be aware of potential impacts on nesting wildlife.
Changes in water levels during the nesting season which is generally May 1 through July
15 in Missouri although it may begin sooner and last longer can destroy nests. Many marsh
birds nest over water as a way to avoid predators, and may abandon them if the water is removed
from underneath. Wetlands are dynamic, and it is very probable that your wetland will require some manipulation
to maintain a desired plant community. Emergent marshes can become choked with vegetation. The goal is to maintain a 50 50 ratio of vegetation
to open water. If the ratio dips to less than 25% open water, consider taking steps to reduce
the amount of vegetation in the marsh. Seasonal wetlands depend upon annual seed production to maintain their productivity.
Over time, plant succession gradually replaces the annual plants with perennial ones that
provide less food. Periodic disturbance is necessary in order to maintain a high percentage
of annual plants in the moist soil unit. Shrub/scrub habitats over time tend to become dominated by trees, which may detract from
the desired plant community. The shrub community typically declines when they are overtopped
by taller trees. Even tree communities change over time. Bottomland woodlands may become dominated by a single
species, or the species desired may decline in abundance. This is especially likely with
oaks since they do not regenerate well in shaded conditions. Manipulation may be necessary
to maintain desired diversity. In all wetland management, it is important
to promote diversity. There are a variety of methods the manager can use to maintain
desired plant communities. Disking changes the plant community and its structure. This is an extremely useful tool
in setting back emergent marshes or restoring seasonal wetlands that have become dominated
by perennial plants. Disked areas could be seeded with a quick growing cover crop like
buckwheat or Japanese millet to provide an annual food source. Soil conditions need to
be dry enough to allow access, so disking is often accomplished in the middle of the
summer. Even then, some areas may be too wet to disk in certain years. Mowing is used to change plant structure
and may influence the plant community, but only if properly timed. For example, hibiscus
or marsh mallow mowed low as it begins to flower greatly reduces its abundance for that
year. Mowing may also be used to set back woody invasion, but seldom kills it. Prescribed burning can change the plant community
and structure. It may be useful in setting back woody invasion and some perennial vegetation,
depending upon the timing and the intensity of the fire. Note that this is a specialized
tool, and you should contact a prescribed burn specialist for guidance and a detailed
burn plan before using this management tool. Water, either its absence or abundance, can
be used to influence the plant community. Some plants such as cocklebur are intolerant
of ponded water. Others like American lotus do not persist well when water is removed.
Knowledge of plant physiology is important if you plan to use this technique. Herbicides can be used to change the makeup
of the plant community. These are typically used as a last resort to control problem plants
such as spot control to knock out invading willow. Be sure that all pesticides are labeled
for use in wetland settings, and read and follow all label directions. Often, two or more treatments or a combination
of two or more methods are necessary to achieve desired results. The frequency of treatment
varies with the site. In some cases, it may not be necessary to disturb the wetland for
several years. Other sites may require disturbance every 2 - 3 years to achieve the desired plant
community. Remember that disturbance treatments will have an influence on nesting wildlife. Consider
ways such as leaving some areas undisturbed to limit potential negative impacts. Disturbances
need to be planned based upon your objectives. Be prepared to deal with setbacks and have a back up plan. A wet spring may prevent you
from completing your planned disking, but some spot application of herbicide to control
invading reed canary grass may be enough to hold you over until next year. Finally, record
what you do and when. Not everything you try will work, and this will give you a record
of what has been done so you can better predict the impacts of future efforts. Wetlands are dynamic and unique, and as
such provide some interesting problems and challenges. We'll discuss a few of
the more general ones. First let's talk about tree and/or shrub invasion. This is an inevitable occurrence
for herbaceous wetlands. Trying to control every buttonbush sprout or willow seedling
is a time consuming chore. Some woody invasion is okay, especially in wetter sites that are
difficult to physically manipulate. Trees/shrubs can provide valuable benefits, but there is
a limit to how much you will want to tolerate in your emergent marsh or seasonal wetland.
Determine ahead of time the level of woody invasion you are willing to tolerate, and
take action before it exceeds your level of tolerance. Plant succession also impacts herbaceous vegetation.
Owners of emergent wetlands and seasonal marshes will have to contend with persistent perennial
vegetation, such as reed canary grass, cattail, primrose, American lotus, and others. These
become major problems when they begin to dominate the wetland. Perennial herbaceous plants typically can
result from prolonged wetness during the growing season, or from maintaining static water levels.
As with trees and shrubs, determine your level of tolerance ahead of time. This may vary
with the plant. For example, you may have absolutely no tolerance for reed canary grass,
but willingly accept 10 - 20% of your marsh in cattails. The majority of these plants
are tough, and most will require multiple treatments in order to achieve adequate control. You may also have to deal with undesirable
annual plants. Species such as cocklebur, sunflower and velvetleaf often show up in
seasonal wetlands, and usually indicate that water is being removed too quickly. Altering
water management to avoid fast drying will help reduce this problem in the future. To
treat existing problems, you can reflood, mow or disk problem sites. If reflooding is
not an option, consider planting an annual crop such as buckwheat or Japanese millet
on disked sites in order to provide desirable cover. If using food plots within your wetland, locate
them in a fashion that makes them most attractive to the targeted species. For example, food
plots for ducks need to be in sites that can be drained for planting early, but yet be
able to be reflooded in the fall. Food plots are often regarded as a panacea for wildlife. A
myth that is too often mistaken for truth. Often natural foods are more than sufficient
to meet wildlife needs, and in many cases are more desirable. However, if food plots
are located and managed well, they can provide important food for wildlife during critical
time periods. Keep in mind that food plots are expensive
to establish, require considerable time and equipment, and may sit high and dry in the
fall if natural flooding/runoff or artificial pumping is insufficient to flood them. Wetland infrastructure, including levees and
water control structures, require periodic maintenance to function as designed. Plan
on conducting periodic inspections of levees to watch for damage by burrowing animals especially
muskrats and beavers and work to maintain permanent vegetation to keep levees from eroding.
Also note that water control structures occasionally fail, and the pipe leading underneath the
levee can sometimes become separated and allow water to pass around it, which can cause the
levee to fail. Do not fall disk or mow prior to flooding in order to avoid violating baiting regulations.
Normal farming operations, such as seeding wheat, are not considered baiting. Contact
your local Conservation Agent or the U.S. Fish and Wildlife Service for specific information. As you make management decisions, keep
your objectives in mind and remember that there is more than one way to achieve those
objectives. Do not be overly afraid of persistent, perennial plants. They are an essential part
of the wetland system, and provide some unique benefits. Determine a level of tolerance for
them, and manage accordingly. Don't let fall waterfowl hunting
guide all your decisions. Waterfowl have different needs throughout the year, and will use a
diverse marsh more than just a feeding area. Remember that seed production isn't
everything Do choose a management strategy that fits your time schedule and resources. The best
management you can do on a site is the one that you are able to implement. Each wetland
is unique, and requires an individual management strategy there is no cook book to managing
a wetland! Don't let that fact intimidate you. Instead, may it encourage you to experiment
and appreciate the dynamic nature of wetlands. There are a host of resource professionals
available to provide assistance on your specific wetland. Don't hesitate to contact
your local Missouri Department of Conservation office, USDA NRCS office, or U.S. Fish and
Wildlife Service office for assistance. Wetlands are fascinating! You have the rare privilege to work with an ecosystem that is
the most productive on earth. Enjoy it!
