Post Oak Savannah or Post Oak Thicket?

Recently, I visited a nearby ranch that is actively clearing yaupon, elm, and other woody plants from the understory of the post oak woodlands. This landowner understands (at least to a certain extent) the importance of creating an open understory to enhance wildlife habitat. While visiting properties in the Harvey WMA and throughout the Brazos Valley, I’ve realized that there is some confusion about the abundance of woody shrubs and vines that dominate much of the landscape. Some of the comments I hear are, “The thick woods provide cover for the deer, right?”, “Do deer eat yaupon?”, “I don’t want to kill any trees, but I can’t get to most of my property because of all the yaupon.”

Brazos County lies completely within the Post Oak Savannah Ecoregion. Merriam-Webster’s Dictionary defines a savannah as “a temperate grassland with scattered trees (as oaks)”. According to Wikipedia, the term savannah originally came from a Native American word describing "land which is without trees but with much grass either tall or short" and by the late 1800s it was used to mean "land with both grass and trees". It now refers to land with grass and either scattered trees or an open canopy of trees. Savannahs are often a transition between forests and prairies. They support a tremendous number of plant and animal species.

Much of the lands we own and manage in Brazos County today are in a condition much different from the savannahs of 100 years ago. Grasslands dotted with post oaks have been replaced by large blocks of bermuda pastures and dense woodlands. Historically, regularly occurring grass fires and periodic grazing created environmental conditions favorable for the growth of annual forbs and perennial grasses of the savannah ecosystem. When these conditions were altered by fire suppression, introduction of exotic grasses, and year-round grazing by domestic livestock, the process of succession took affect.

Succession is the process in which the same area is successively occupied by different communities over time. Through the process of succession, bare ground [created by strip-mining, land leveling, or river deposited sand bar] will, over the course of tens, hundreds, or thousands of years develop into a stable climax community of perennial [woody] plants and trees. In the absence of fire and periodic grazing, the grassland savannahs of Brazos County and surrounding areas have developed into shrub-woodlands. As a result, bobwhite quail, eastern wild turkey, Houston toad, and other desirable wildlife species have disappeared. A recent study described a post oak savannah site which in the early 1800s documented more than 28 bird species and 300 plant species. In year 2000, after undergoing the same land use changes occurring in the Brazos County area, that same piece of property recorded only 4 bird species and less than 25 plant species.

There is good news! In his 1933 textbook titled Game Management, Aldo Leopold, the father of wildlife management, stated that “…game can be restored by the creative use of the same tools which have heretofore destroyed it - ax, plow, cow, fire, and gun." In other words, activities such as mowing and cutting (ax), disking (plow), grazing (cow), prescribed burning (fire), and/or hunting (gun) can be used to return the yaupon infested woodlots and weed-controlled hay pastures to grasslands with an open canopy of trees.

Although deer and birds will eat leaves, twigs, and berries of yaupon, dense woodlots provide travel corridors for deer movements in a highly fragmented landscape, and some bird and mammal species prefer dense woodlands to an open canopy, overall plant and animal diversity increases with the removal of yaupon, elm, and eastern redcedar from the understory of your wooded properties. Thinning or removing these woody plants will allow more sunlight to reach the ground, promote grass and weed production, and allow for forest regeneration. Additional benefits include decreased erosion and increased ground water re-charge. Remember, except for the creek and river bottoms, your property used to be a savannah which supported hundreds of plant and animal species which are absent from the yaupon crowded woodlots of today.

Stay tuned for recommended methods of removing nuisance understory brush and increasing diversity on your property.

Wetland Construction and Management (Part 2)

Wetland management techniques focus on manipulating water levels to have desired effects on wetland plant communities. Wetlands are dynamic systems. Therefore, wetland management must also be dynamic and often requires professionals to identify the individual and changing management needs of a wetland. Management is a continuous, variable, and dynamic process. However, the basic techniques of wetland management are relatively straight forward. The goal of wetlands designed the way I’ve described in this post is to grow annual plants which will produce large amounts of seeds that provide a valuable food source to many wildlife species, especially dabbling ducks such as mallards, wigeon, gadwall, and teal. Annual plants respond favorably to wetlands which gradually dry out during the spring and summer months and to soils that are periodically disturbed. Therefore, water level manipulation and disking are the 2 most common and useful wetland management tools.

In our part of the state, the most beneficial time to begin releasing water from a wetland is late winter to early spring when soil temperatures reach about 60 degrees F. Valuable plants such as pink smartweed respond favorably to this early drawdown. However, if drawdown is delayed until mid-spring to early summer, desirable plants such as barnyard grass will grow rapidly. Regardless of the timing of drawdown, drawdown should be made slowly, often taking up to 1-2 months to completely drain.

Once the wetland is dry, mowing and burning can control undesirable plants such as cocklebur, sumpweed, or sesbania and encourage more beneficial food plants. Mowing and burning can also reduce heavy stands of rushes, sedges, and other species that can take over an area and crowd out other plants. Once monocultures and undesirable plants become established, mowing and burning will become only temporary fixes and require follow up treatments at least once a year. Disking can also be used to reduce perennial species and increase seed producing annuals. Disking is usually only recommended every 3-4 years.

With proper water level manipulation and soil disturbance, an abundance of native plants and seeds can be produced to attract migratory waterfowl. This method is recommended over planting crops such as corn, milo, soybeans, and rice. However, if a crop is desired, choose Japanese millet. The first step in growing Japanese millet is to obtain a soil analysis for the area to be planted. Contact NRCS or the Texas AgriLife Extension county offices for assistance submitting and interpreting results. Disk and harrow to prepare a good seedbed. Blend the seed with the fertilizer and broadcast over the field at a rate of 20lbs/ac. Because Japanese millet can produce mature seed in 60 days, it is recommended to plant from July 1 to August 15 so that the seeds are mature as late as possible prior to the first frost. An alternative seeding method for Japanese millet is to delay drawdown until mid- or late summer and then quickly reduce the water level to expose wet mudflats. Then broadcast the seed and fertilizer at the same rate as above. If you plan to hunt near of over this wetland, be sure to check with a local game warden to be sure you are not illegally baiting ducks through this practice.

At some point, your wetland will be invaded by nuisance plants and animals that should be reduced or eliminated. Cocklebur, sumpweed, and sesbania respond favorably to rapid drawdown in the summer. While a slow drawdown in the late winter and early spring can help to minimize these nuisance plants, mowing or herbicide treatment may be necessary to reduce or eliminate them. Once detected, these plants should be treated quickly to avoid seed production which will increase problems in subsequent years. Because willow or cattail cannot withstand competition, these pest plants are best avoided by producing desirable plants on bare moist soil in late spring or early summer. Since there is often an abundance of bare moist in the first year of a new wetland unit, it may be necessary to plant Japanese millet or other beneficial plant to keep willow and cattail from establishing.

Beavers can be expected to occupy your wetland project. Beavers often plug water control structure and/or burrow into levees. To keep beavers from plugging your structure, place a pen constructed of cattle panel or similar material around the control structure. Although beavers may still stack material along the fence, it is much easier to remove debris along a fence than it is in a control structure. Nutria are fast reproducing herbivores that can become quickly overpopulated and destroy vegetation within a wetland. They will also clog control structures and burrow into levees. Every attempt should be made to remove nutria from your wetland unit. Feral hogs will also do extensive damage to levees and wetland areas. Hogs should be trapped and shot whenever possible to protect the investment you’ve made in your wetland project.

Remember, wetlands are more than just a place to duck hunt. The collective efforts of creating, restoring, and enhancing wetlands on your properties will have a tremendous impact on water quality and quantity and wildlife habitats.

Wetland Construction and Management (Part 1)

Those of you who have spent a little time in the field with me know that wetlands and waterfowl are my favorite habitats and wildlife species to talk about. That’s why I was excited to see the comments about wetlands made by Richard and Dan Dawson on the Harvey WMA blog last week. Since other Harvey members could probably benefit from information on wetland construction and management, I’ve dedicated to post discussing the basics. All of the following information can be found in a Texas AgriLife Extension publication titled “Techniques for Wetland Construction and Management”. As always, if you would like additional information or a copy of the publication, please contact me.

Many people see wetlands as “wastelands” or as areas suitable only for snakes, alligators, and mosquitoes. Wetlands, however, provide many important ecological functions as well as recreational and aesthetic functions to those who learn to recognize them. Wetlands help regulate the climate, provide flood and erosion control, store and recycle nutrients, protect water quality, provide wildlife habitat, and provide recreational hunting and wildlife viewing opportunities. Many of these functions are enhanced on wetlands that are closely tied to a river system and waterfowl travel corridor like those of the Harvey WMA. Many of you have the opportunity to create, restore, or enhance wetlands on your property, and I hope the remainder of this post will provide you with the basic tools needed to begin.

The first step to a wetland development project is to assess the soil characteristics, seasonal availability of water, abundance of wetland adapted plants in the soil, and existing plant communities. Impermeable soils, adequate surface water during the fall and winter, and a community of annual seed producing plants indicate an area suitable for wetland development. After a suitable site has been identified, contact a private land surveyor or engineering personal with NRCS to supply an elevation survey accurate to one-foot contours. This level of accuracy is necessary for best placement of levees and control structures. Waterfowl and other wetland wildlife are attracted to plants that grow in shallow (<3ft).

Before beginning levee construction, contact a qualified contractor or NRCS personnel to provide soil sampling and engineering design to ensure that levees (1) will not leak, (2) will impound the desired amount of water, and (3) will withstand extreme flood events. Levees should not be more than 4-5 feet tall. The distance from the water level to the top of the levee should be between 18 and 30 inches. Levee side slopes should be no steeper than 3:1, but may be as gradual at 10:1. Levee elevations should be uniform throughout to prevent erosion at lower areas where floodwaters would overtop the levee. The levee should, however, be at its highest point near the control structure and discharge pipe to prevent washouts at this important location. A large and well-designed spillway should be set about 1-6 inches above the normal water level so that flood waters will immediately pass through the wetland and avoid placing unwanted stress on the levee system. Levee material should be borrowed from inside the constructed wetland area. This will create a narrow barrow ditch which may occasionally be more than 3 feet deep along the inside of the levee. If a levee will completely surround the wetland, remember to leave an area without a borrow ditch to allow access by hunters and/or equipment. After levee construction, immediately re-vegetate exposed soil on levees and borrow areas. Common or coastal Bermuda grass offers the best option for sod-forming grasses to hold soil and reduce erosion on these areas. Roots from woody plants and trees can penetrate the levee embankment and cause a washout. Shredding or herbicide treatments should be used to remove trees from levees.

Water control structures provide the ability to control water levels in the wetland. The most common types of structures are flashboard risers, screw gates, flap gates, and drop pipes. The flashboard riser is the most versatile and desirable. A flashboard riser functions by using a series of wooden, aluminum, or PVC “boards” fitted in slots to form one side of the riser box. Boards are added or removed to regulate water levels in the impoundment. The riser box is coupled to a culvert pipe that passes through the levee to discharge water. Install flashboard riser(s) near the lowest point(s) of the wetland to provide for maximum drainage capability. When placing risers in the levee, be sure that the top board in the riser box is the same elevation as the normal operating water level will be.

Check back next week for Part 2 on how to manage your wetland once it is built.

Wildlife and Fish Management Calendars

During Tuesday's Harvey WMA meeting, I was asked to discuss habitat management activities that should be performed during the spring and summer months. It later occurred to me that I had calendars in my truck that contained much of the information I presented. I had intentions of giving them out, but forgot. So, I wanted to let you know where you could get that information for yourselves.

Clicking on the title of this post will direct you to Texas Parks & Wildlife's Private Lands Calendars in PDF format. This calendar contains "Habitips" in addition to beautiful pictures and information about TPW's Wildlife Management Areas.

I also highly recommend you take a look at the Texas AgriLife Extension's Wildlife and Fish Management Calendar for Texas and the Southeast. This is a full-color calendar that will teach you how to manage your property for wildlife and fish, but also when to perform critical management tasks. It contains information on how to improve fishing in your ponds, understand population dynamics of your deer herd, age deer in the field, select supplemental forages for wildlife, etc. A PDF of this calendar can be obtained from http://tcebookstore.org/ where it can also be purchased for $7.95+ tax and shipping.

For those of you managing green-tree reservoirs and moist soil unit wetlands for wintering waterfowl, go to http://www.tpwd.state.tx.us/publications/pwdpubs/media/pwd_pr_w7000_1179a.pdf. TPWD's East Texas waterfowl biologist, Corey Mason, has put together a one page wetland management calendar of recommended activities.

I've included 3 great resources for wildlife management guidelines. However, all 3 provide only general guidelines. If you need more information about any of these activities and how to apply them to your properties, please contact me.