Basic Facts/Concepts/Issues in Range/Wildlife/Livestock Management

Jim Stanley								2005

Soil

The most important thing on your land is not the animals or the trees or the grass, it’s the dirt.  Without soil you can’t grow anything and without plants you can’t raise any livestock or wildlife.  Nothing grows on rocks (except lichen).  Once lost, it will take centuries, if ever, for soil to be replaced.  Therefore, efforts at erosion control should always be given serious consideration.  The potential for erosion becomes greater as the slope increases and/or the amount of grass decreases.  Erosion can remove the soil from under trees and bushes; a good stand of native grasses is the best thing you can have to prevent erosion.

Much of the soil loss in the Hill Country in the last 50 years has occurred because first cedar was allowed to take over pastureland, which then shaded out and stole moisture from other woody plants and forbs and finally grasses, and then the soil was left with nothing to hold it in place.  The result is cedar brakes with nothing but rocks on the surface under the bushes, essentially worthless land.

This might lead some to conclude that removal of cedar from steep slopes is the right thing to do, but this is often the worst thing that can be done.  If the soil has already been eroded away, there is little reason to remove the cedar from the slope.  If there is still soil in places on a steep cedar slope, it is very difficult to remove the cedar and not expose the soil to significant erosion before the slope can regrow enough grass to protect it.  If cedar is to be removed from such slopes, it should be done gradually over several years, by hand, and by also laying the branches and trunks across the slope to catch runoff.  Done gradually, this allows grass to come back before large areas are cleared, thus reducing the chance of erosion.  This method works fine for small properties, but obviously becomes more difficult as the acreage increases.

Cedar

Despite rumors to the contrary, Ashe Juniper, which we call cedar, is native to the Hill Country, it just used to be confined to steep slopes and some draws.  It is, in fact, almost the perfect plant for this area as it has very few diseases or pests, is quite drought tolerant, can grow in almost any soil and very little of it at that, and it reproduces well.  Unfortunately, for all of the same reasons, it is also one of the biggest pests.  Cedar does provide cover for many different species of birds and animals, and food for some as well.  As with most pests, it is not so much the individual properties that are a problem, but the numbers.

Cedar has taken over much of the Hill Country because, beginning in the mid 1800s when Europeans began settling this area, they began to overgraze the tall grass prairie and to suppress fire, both of which enabled cedar to get a start and survive in areas where it once did not.  The problem is also exacerbated because nothing eats it, or at least not enough to control its growth.  Therefore, just about any place where cedar has not been controlled by man will have excess cedar growth.

The Kerr Wildlife Management Area high fenced a 96 acre section of savanna covered with grass 40 years ago and left it to “let Nature take its course”.  There were no animals inside the exclosure and nothing was done by man.  The area is now a complete cedar brake, no grass, and mostly rocks covering the ground!

Cedar trees have two properties that are detrimental to surrounding vegetation.  First, because of the structure and very high surface area of their scales (leaves) and litter, they intercept a high percentage of light rainfall which is then re-evaporated back into the air so nothing in the vicinity benefits.  Secondly, they absorb and transpire a lot of water, thus competing with other plants.  For these reasons, as well as the shade produced by them, cedars make it difficult for other plants to grow around them.  

You will encounter all sorts of (frequently exaggerated) values for how much rainfall is intercepted by cedars and how much soil moisture they use.  Be skeptical of the larger numbers being thrown around.  A study of the original literature or discussions with the authors will reveal that the numbers for rainfall interception and moisture absorption vary greatly with the amount of the average rainfall, size of the cedars, which part of the hill country the work was done in, and also the experimental procedures.  What is not in dispute, however, is that, compared to similar sized hardwoods, cedars do in fact intercept more rainfall and absorb more moisture.

Mechanical methods of cedar removal work well on larger acreages, especially if they are on flat to gentle sloping terrain. There are pros and cons to all of the different methods.  The primary consideration in all cedar removal plans is to do no harm, to cause no erosion in the process (see above). Based just on protecting the soil and surrounding hardwoods, the most preferred cedar clearing method is hand clearing by chain saw and laying some of the branches and trunks across the slope to catch leaves and soil, followed by a skid-steer cedar snipper, a hydroax-type mulcher, and finally, the least preferred, a bulldozer.

Grass

Most ranchers will tell you they are in the business of raising beef, or sheep or goats, but in reality, they are in the business of raising grass and using the animals to harvest it.  Feedlots are in the business of raising beef.  When it comes to managing grass and grazing animals, there are three very important principles.  First is the principle of “take half, leave half” as it pertains to how much of a grass plant to harvest at any one time.  Second is the principle of some species of grass being “increasers” and some being “decreasers”, all of which is an understanding that animals have favorite foods and unfavorite foods. Thirdly, there is the concept of “carrying capacity”, which is how many animals a property can support, long term.

We all know that if a flower or a tree sprout crops up in your yard, and you keep mowing it, it will eventually die, but that even if we mow the grass every week, it will do just fine. But what we may not realize is that the grass is surviving because we only mow a little off the top most of the time, and also the turf grasses in our lawns are unusual.  Most all native grasses are bunch grasses, and it turns out that if you mow (or graze) over half of the top off repeatedly, it will eventually decline and die.  It has to do with the fact that if we cut too much off the top, the small leaf area left can’t carry out enough photosynthesis to support the extensive root system, so some roots die, then, with fewer roots some more of the top dies, etc. etc. Just like it takes money to make money, it takes grass to grow grass.  In fact, the more grass left ungrazed, the more grass will be produced the next growing season, even with somewhat less rain.  Overgrazing is like spending principal.  The old rancher attitude that “if there is grass left by Christmas, I didn’t have enough cows”, is just wrong.

There are some species of grass that just about nothing eats (most all of the threeawns), some that produce so little foliage that they are worthless as forage (Texas grama, sixweeks grama, red grama, little barley, hairy tridens) and others that are good forage and most animals favorite (sideoats grama, Indian grass, switchgrass, big bluestem, little bluestem, meadow dropseed, Texas cupgrass).  Animals left in a pasture too long will continue to eat their favorites over and over which will eventually cause the decline in those favorite, nutritious grasses (for reasons discussed above) and those grasses are called “decreaser” grasses for that reason.  The uneaten, less favorite or worthless forage grasses, however, will continue to thrive and eventually take over the pasture spaces left by the declining/dying decreaser grasses, and the former are therefore called “increaser” grasses.  So it is not enough just to not let the animals eat too much grass in any one season, it is important to control which grasses they are eating as well.  This calls for rotational grazing plans, which are not as simple to accomplish properly as it might seem.  For help with rotational grazing plans, contact your local Texas Cooperative Extension or USDA/NRCS agent.

Finally, the concept of carrying capacity is important.  Carrying capacity is the number of animal units (see below) that a particular property can feed LONG TERM without diminishing the quality of the pasture.  It is not the number of animals you currently have, nor the highest number you can raise in any one year.  In fact, given the fact that the number of animals you can feed depends on how much grass you grow and that in turn will vary with the amount of rainfall, the carrying capacity tends to be the number of animals that can be fed even in less than average rainfall years.  In this part of the Hill Country, non-irrigated pastures in good condition can usually support one animal unit on a minimum of about 25 grazable acres.  Areas under cedar bushes, steep hillsides, or rocky areas are not considered grazable.  Properties with much of these areas might only support one animal unit to every 100 to 200 acres!  Pastures with poorer grass cover or unpalatable grass can obviously not support as many animals as pastures with good quality grass.

Animals

Range scientists rate different animals by how much forage they require, based on their size and digestive capabilities.  Everything is related to an average 1000 lb cow with her calf by her side for half the year.  This cow and calf are called an animal unit and are expected to require 26# of dry grass per day.  Other types of animals are rated by how many animals eat the same amount as the cow and calf to determine how many animals it takes to make an animal unit.  For instance, one horse or one bull equals about 1.3 animal units, 6 sheep or goats equal one animal unit as do 7 white-tail, 5 axis, 9 blackbuck, 4 aoudad or 2 nilgai.

But just knowing how much each animal eats is not enough to manage them properly, you also have to know what they eat.  Obviously cattle and horses eat mostly (90% or more) grass so they eat very little browse (leaves of woody plants) or forbs (broadleaf weeds and wildflowers).  White-tail are almost the reverse, they prefer browse and will readily take forbs, but cannot digest more than about 15% grass, and then only when it is new growth.  For this reason, cattle and white-tail do not compete with one another, and in fact cattle eating grass make it possible for more forbs to grow so they actually improve the habitat for deer.  Sheep, goats, and most common exotics fall in between deer and cattle, they can and will eat all three types of forage, which gives them an advantage over both deer and cattle in marginal pastures.  The distribution of what different animals eat in different seasons can be obtained from Kerr Wildlife Management Area.

It is very important to monitor your pasture and observe what plants are being eaten and which are not.  This knowledge, together with the knowledge of what each of your animals most like to eat, and least like to eat, will tell you if you are overstocked by that species.  For instance, if all live oak shoots are being eaten before the winter is over, live oak being low on the white-tail food preference, then you have too many deer.  Similarly, if the only grass taller than 3” in your pasture is threeawn, you are overstocked with grazers.  Also, note that if you see any of the following weeds in your pasture, they are not to be considered deer food, they are there because nothing eats them: 2-leaf senna, buffalo bur, cowpen daisy, frost weed, horehound, thistles, mealy blue sage, Mexican hat, prairie verbenia, queen’s delight, silver-leaf nightshade, snow-on-the-mountaiun.

Trees

We have more hardwood trees growing in most of the Hill Country than were here 150 or so years ago.  This is so because after European settlement, the grass was grazed short, allowing more trees to get a start in the grassland. As more and more trees sprang up in what had been a tall grass prairie, the habitat changed from one that deer did not like (tall grass) to one that deer do like (savanna). We have more trees now than we will in 20 or 30 or 50 years from now, mainly because of the deer.  The high deer populations are now eating every young tree sprout before it has a chance to grow above the browse line.  A casual examination of almost any property in the area will reveal a distinct browse line on all trees and no small saplings anywhere within reach of the deer.  There are essentially no young trees around to replace the old trees, so without man’s intervention, we will again revert to a more open grassland.

Often, the only small trees one can find are either hanging off the side of a steep bank or growing up inside cacti or agarita.  This will continue to be the case unless we either greatly reduce the deer and exotic populations and/or cage areas with exclosure fences and/or plant trees ourselves inside exclosures.  It is not so much that the habitat will be less healthy with fewer trees, but that it will be different and for individuals who have fallen in love with the country as it is now, it will have a different look.  If you want to leave your property in the same state as you found it, you should plant a wide variety of NATIVE trees all around your property.  In grazed areas, all new trees need to be caged until they have heavy bark, stout trunks, and two thirds of their foliage above the browse line. The Bamberger Ranch Preserve is an excellent example of a place that has planted thousands of trees, and it shows.

Oak Wilt

One of the things that is hastening the disappearance of older trees is oak wilt.  Oak wilt is a fungus that infects oaks, plugs up the vascular system, and kills the trees.  Any oak can get oak wilt, but red oaks such a Spanish oaks and blackjack oaks are the most susceptible, followed by live oaks.  White oaks such as shin oaks, post oaks Lacey oaks and chinquapin oaks are much less likely to get oak wilt.  Trees can get oak wilt two ways.  Sap beetles or bark beetles get spores on their bodies from infected red oaks and can infect another tree that has an open wound seeping sap. This is the way “new” oak wilt centers are started.  The second, and actually far more common way for a tree to be infected is through the roots that are connected (either because one tree is the “daughter” of the other or by root grafting).

Although the red oaks are very susceptible to oak wilt, they usually are only infected by the spore-carrying beetle as they are not as likely to be connected via roots as live oaks are, so when infected it is usually only the one red oak tree that dies.  The impact of oak wilt on live oaks is the most severe, however, partly because they tend to be more numerous but also because they are much more likely to be connected to neighbors via their roots.  Thus,  if one live oak gets the disease, it is likely that many of the neighboring live oaks will also get it.  This is why we lose many more live oaks than other species to oak wilt.

The most important thing to know about oak wilt is that in order to insure that you do not get a new oak wilt center started, you should always paint all cuts, wounds or broken limbs  on all oaks immediately.  This prevents the sap beetles from transferring the spores to the sap oozing from the cut.  Once infected, red oaks tend to die so fast that no treatment is likely to be effective.  On the other hand, infected live oaks take some time to transfer the fungus via their roots to neighboring trees, so once oak wilt has been identified in one tree, there may be time to prevent it from spreading to neighboring trees.  There are only two methods proven to be effective in preventing neighboring trees from becoming infected.  One is injecting solutions of the fungicide propiconazole, brand name Alamo, or its generic equivalent Quali-Pro, into the flare roots around the tree to be protected.  The other method is to dig a deep (5’) trench 100’ from the infected tree(s).  It is important to note that the distance between the infected tree and the tree to be protected as well as the timing of the treatment is crucial to success.  Therefore, whenever oak wilt is suspected, call the Texas Forest Service for guidance as to when, where and how to conduct any preventative treatment.