Natural Resources Conservation Service s43

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NATURAL RESOURCES CONSERVATION SERVICE

WETLAND WILDLIFE HABITAT MANAGMENT (acre) CODE 644 GENERAL PRACTICE SPECIFICATIONS FOR

MOIST-SOIL MANAGEMENT

GENERAL MOIST-SOIL VEGETATION Water level manipulations are one of the The timing of a drawdown has an most effective tools in wetland important influence on the composition management, provided fluctuations are and production of moist-soil plants. An well timed and controlled. independent water supply for each Manipulations are most effective on sites management unit is required to optimize with a dependable water supply, an food production, maintain the potential elevation gradient that permits complete to control problem vegetation, and make water coverage at desired depths over a food resources available for wildlife. majority of the site, and the proper type of water control structures that enable Stoplog water control structures or water to be supplied, distributed, and flashboard risers that permit water level discharged effectively at desired rates. manipulations as small as 2 inches The size and location of structures are provide a level of fine tuning that important, but timing, speed, and facilities control of problem vegetation duration of drawdowns and flooding also or enhancement of desirable vegetation. have important effects on plant composition, plant production, and avian SCHEDULING DRAWDOWNS use. When optimum conditions are not During most years, early and midseason present, effective moist-soil management drawdowns result in the greatest quantity is still possible, but limitations must be of seeds produced. However, there are recognized. exceptions, and in some cases, late drawdowns are very successful in TIMING OF DRAWDOWNS stimulating seed production. Drawdowns are often described in Smartweeds tend to respond best to early general terms as early, midseason, or drawdowns. late. These drawdowns are considered with the context of the length of the local EFFECTS OF DRAWDOWN RATES growing season. Early drawdowns are those that occur during the first 45 days Slow drawdowns (2-3 weeks) usually are of the growing season, whereas late more desirable for plant establishment drawdowns occur the latter 90 days of and wildlife uses. The prolonged period the growing season. of soil saturation associated with slow drawdowns creates conditions favorable

Conservation practice standards are reviewed periodically, and updated if needed. To obtain NRCS, SC the current version of this standard, contact the Natural Resources Conservation Service. Sept, 1999 643 - 2 for moist-soil plant germination and TYPICAL DRAWDOWN SENARIO establishment. For example, slow A typical moist-soil scenario can be used drawdowns late in the growing season for many years once competing can result in seed yields of 700 pounds vegetation has been eliminated through per acre. Slow drawdowns also provide mowing, disking, burning and water shallow water over a longer period, level manipulation; and a diverse ensuring optimum foraging conditions community of natural waterfowl food for wildlife. When water is discharged plants has been established. slowly from a unit, invertebrates are trapped and become readily available to 1. Drawdown during late February to foraging birds along the soil-water early March to expose soil. interface or in shallow water zones. Drawdowns should be gradual to These invertebrates provide critical concentrate invertebrates for protein rich food resources required by waterfowl and shorebirds. pre-breeding and breeding female ducks, 2. Maintain drawdown through April newly hatched waterfowl, and for germination of target plant shorebirds. Shallow foraging is required species. Standing water should not by the vast majority of species. Slow cover the area during this period. drawdowns lengthen the period for 3. In late April to early May, saturate optimum foraging and put a large soil to the surface by replacing lower portion of the invertebrates with the stoplogs in the flashboard riser. foraging ranges of many species. Maintain until mid-October. 4. Mid-October to early November FALL FLOODING STRATEGIES flood impoundment to an average Scheduling fall flooding should coincide depth of 9 to 12 inches. Delay the arrival times and population size of flooding if standing vegetation is fall migrants. When flooding is possible green. (Spot burns may be from sources other than rainfall, fall conducted prior to flooding, if flooding should commence with shallow conditions are conducive.) inundation on impoundments suited for 5. Closely monitor water levels blue-winged teal. Impoundments with throughout the fall and winter to mature but smaller seeds, such as panic maintain an average depth of 9 to 12 grass and crabgrass, that can be flooded inches over the majority of the area. inexpensively are ideal for these early REFERENCES migrating species. Flooding should always be gradual and should maximize Fredrickson, L. H. 1991. Strategies for the area with water depths no greater Water level Manipulations in Moist-soil than 4 inches. As fall progresses, Systems. U. S Fish and Wildlife Service additional units should be flooded to Leaflet 13.4.6. 8 pp. accommodate increasing waterfowl populations and other bird groups such Williams, R. K.,, R. D. Perry, M. B. as wading birds. A reasonable rule of Provost, and S. E. Adair. 1998. thumb is to have 85% of the surface area Management of South Atlantic Coastal of an impoundment flooded to an Wetlands for Waterfowl and Other optimum depth at the peak of fall Wildlife. Ducks Unlimited. Memphis, migration. TN. 29 pp.

NRCS, SC Sept, 1999