by FAO STAFF
A Technical Meeting on Forest Grazing, held in Rome from 29 March to 3 April, is reported later in this issue. This paper was prepared as one of the background documents for the Meeting.
In most countries both trees and forage are important but there is not enough of either resource to satisfy all needs. Therefore, in considering forest grazing, the need for a type of management which will permit the production of wood products as well as forage should be kept in mind. 1
1 See also Grazing and Forest Economy, FAO Forestry and Forest Products Study No. 4, 1963.
Accepting the production of wood products as a prerequisite, forest grazing management will have the following objectives:
1. a high production of desirable forage species on a sustained yield basis in so far as site and growing conditions will permit;2. maintenance or rehabilitation of soils in a stable and productive condition, which will permit the high production of forage plants;
3. high yield of animal products based on ample forage supplies.
Basic to such high production are the following facts:
(a) The animal is the end product of the process of forest range management and to produce well the animal must have an abundant supply of nutritious forage. At the same time; the animal must be of a breed and kind that is adapted to the conditions of the range and will make the most economic and efficient use of the forage available.(b) Plants are complex living organisms requiring an ample food supply to grow vigorously and abundantly from year to year. Their growth -requirements must be respected and the plants must be carefully guarded against abuse.
(c) The soil is the source of food for the plants and provides the medium in which plants grow. To produce abundantly the nutritious forage plants required by grazing animals, the entire soil complex, the physical structure, the micro-organisms and the organic matter must be protected.
In this combination of soil, plants and grazing animals with which we must deal in forest grazing management, primary attention should be given to the welfare of the soil and the plants. Without soil and forage plants grazing animals cannot exist, and it is a well-established fact that, wherever there is an abundant supply of nutritious forage growing on a stabilized soil, the production and growth of the animal will, under a program of good range management, take care of itself. This, of course, is disregarding the effects of insects, diseases and other factors which may affect animal production.
Forest ranges which can be described as in good condition are producing close to their optimum of nutritious forage because most of the precipitation which falls is readily absorbed by the soil; and the soils on those ranges are able to give their best to plant growth. This in turn is reflected in high animal production. But if the animal begins to abuse the plant through, for example, overgrazing or continuous grazing during critical growth periods, the plants lose vigor, their roots begin to shrink, eventually they die and are replaced by species inferior for grazing. In the meantime, the soil, no longer adequately protected by a plant cover or firmly held by a thick mass of roots, begins to wash or blow away; thus moisture and nutrients needed by the plants and by the grazing animals are lost and so the yield of forage and animal products is reduced. Unless corrected, the process of deterioration will continue, faster and faster.
Many of the forest ranges of the world are in some stage of deterioration. To improve the ranges and their productivity through grazing management requires exactly the opposite process from that just described. Plants must be permitted to accumulate sufficiently so as to check the run-off of precipitation and to return litter and organic matter to the soil. As the soil improves, the density and volume of plants improves and, in turn, the production of the animal increases.
The level at which ranges can be expected to produce forage, animal and forest products and the rate at which they can be expected to recover from their depleted condition under improved range management depends a good deal upon the climate in which they are found. There are some major differences in climate which affect the growth and use of forest range forage and which are important in appraising forest range practices.
Figure 1. - Range deterioration
Semi-arid temperate zone
Forest grazing has probably been more successfully practiced, and for a longer period of time, in the semiarid temperate zone than any other major climatic area of the world. The native forage produced in the zone is nutritious and it retains its nutritive qualities so that it is well-suited for livestock production. Animal diseases and insect pests generally do not present serious problems.
This zone is characterized by considerable fluctuation in seasonal temperatures and relatively light annual precipitation. In some parts, precipitation may be concentrated in winter and early spring while other parts may receive summer rainfall. In many cases, there is a prolonged dry period each year and sometimes, if normal precipitation fails, drought and the resulting shortage of forage becomes a serious problem in range management and livestock production. Emergency supplies of forage are desperately needed in such cases to save livestock from starvation.
This limited precipitation produces rather open forest stands, and tree growth is relatively slow. Beneath the trees, however, there is considerable herbage growth quite suitable for use by livestock and game. In the warmer parts of the winter precipitation area the vegetation grows from late autumn to early spring. The summers are hot and the vegetation is dried and of little grazing value. However, in the colder parts, some of the precipitation may come as snow, and growth of herbage does not begin until spring melts the snow and warms the soil. Growth is made over a relatively short period in late spring and early summer and the forage remains nutritious into late summer. Summer rainfall of course produces summer growth of forage which is usually best grazed during summer and autumn, although on some ranges yearlong grazing is practiced.
There has been much abuse and deterioration of forest ranges in the semi-arid temperate zone and they are not producing as much forage or livestock products as they could and should. In addition, the yield of wood products is often impaired and watersheds are in a critical condition. Improvement in grazing management is needed.
Humid temperate zone
In this type of zone, moisture is not usually a limiting factor in the growth of forests and herbaceous vegetation. In many cases, the favorable growing conditions produce rather dense stands of hardwoods, or a mixture of hardwoods and conifers, and the amount of herbaceous and shrubby vegetation is limited. The tree reproduction of many hardwood species is palatable so that livestock using these forests often do damage to the trees. Inasmuch as game animals are usually present, most of the forage produced is needed for them, but even with game grazing damage occurs when numbers exceed the forage supply.
In some parts of the warmer belts of the zone, a more open growth of coniferous forest permits a heavy growth of grass and other herbaceous vegetation. It is possible that repeated fires may have maintained this condition in some cases and certainly the heavy understory vegetation presents a fire hazard unless removed. During the growing period, this vegetation is reasonably nutritious but soon afterwards it drops below the nutritive level for maintenance of the livestock and must be supplemented. Grazing seldom removes the bulk of the herbage produced, so that good growing conditions must often be maintained by burning during moist periods of the year. Under such a system, great care must be exercised to protect the more valuable and palatable species from abuse, either from grazing or fire.
A third situation found in the humid temperate zone is represented by the alpine and sub-alpine pastures. They are found in high altitude, cool belts where precipitation comes mostly in summer and the vegetation grows through much of the summer. These are often intensively managed ranges, interspersed with the forest, and cannot be used at other times because of snow and cold. The forage remains nutritious throughout the summer and provides excellent grazing primarily for herds of dairy animals.
Humid tropical forests
In the humid tropics there are two major forest grazing situations, the heavy tropical forest and the savanna forest. Rainfall may be fairly heavy yearlong or the pattern may be about six months of heavy rain, during which time the herbage is produced, with the other part of the year quite dry. There is little or no grazing in the heavy tropical forest except after the trees have been thinned or felled so the land can be grazed or cultivated. Even then, many of the grasses which become established are not good forage species and there is always a struggle to keep trees from recapturing the land. Periodic burning is needed to maintain the grass, but when fire is not wisely used soils and sites deteriorate markedly.
The savanna forest produces a grazing situation very similar to that found in the warmer parts of the temperate humid zone - a heavy growth of grass and other vegetation but with rather low nutritive quality other than during the growing season. Here, too, fire has played, and continues to play, an important role in maintaining this grassland aspect and in keeping the vegetation reasonably usable by livestock.
Arid tropics
The arid tropical parts of the world range from sheer desert to a scattered tree-savanna and in no case is an abundance of herbage produced. Precipitation occurs over a rather limited period and during the remainder of the year it is very dry. Herbage growth, of course, occurs when there is sufficient moisture and since this may vary from region to region, a nomadic type of grazing is practiced. Water for livestock is very limited so that some parts of the range are used only occasionally with perhaps some additional game use.
Figure 2. - Forage furnished by different plants on an improving range
This is probably the biggest and most serious problem of forest range management in many parts of the world today. The scant forage production, the poor development and low production of animals, the catastrophic periodic starvation losses of livestock, particularly during periods of drought, and the serious erosion of soil by both wind and water, all join in stark testimony to this lack of balance of numbers with grazing capacity. In addition, many countries do not produce sufficient crop-land forage to offset the range, and that which is produced is often considered too valuable to feed to range livestock.
Grazing capacity is defined as the ability of a range unit to give adequate support to a constant number of livestock for a stated period each year without deteriorating with respect to this and/or' other proper land use. This definition implies a balance between forage and number of livestock but does not mean much in range management unless there is a reasonable knowledge of what constitutes the forage supply. It should first of all be clearly understood that not all vegetation that grows on a range is forage. The amount of forage a plant can furnish depends upon such things as the preference of animals for it, its edibility or palatability, the amount of herbage which must remain on the plant to produce sufficient plant food, and its ability to withstand grazing.
A desirable forage plant must be able to compete under grazing with other forms and species of vegetation and to provide a protective cover of vegetation and litter to guard the soil against erosion and to rebuild sites that are deteriorated. Strong seeding habits or the ability to spread vegetatively are desirable in forage plants as is a large root system which can withstand wide variations in soil moisture and temperature and trampling by livestock.
The management of a range, however, and the balancing of numbers of animals with grazing capacity cannot be based on individual plants alone but rather on the aggregate of all the forage-producing vegetation. It is true, however, that particular attention should be given to certain key species which furnish a large part of the forage and which must be maintained in high vigor in the stand or which, on ranges in deteriorated condition, it is desirable to increase. These plants should not be grazed beyond their safe limit even though there appears to be considerable ungrazed herbage remaining on the range.
Grazing capacity should not be assessed to include heavy utilization of the less desirable plants because under such a practice the more desirable and palatable plants will be overgrazed and killed off. Considerable herbage from ungrazed or partially grazed plants, left on the ground, is important in maintaining or rebuilding good soil and watershed conditions. Physical and biological deterioration of the soil, brought about by a lack of balance between numbers of animals and the forage supply, reduces the production of both forage and animal products. Other good range management practices cannot offset the effects of too many animals.
In some parts of the world, particularly in semi-arid zones, years of severe drought, when precipitation is considerably below the average, cause scant forage production, severe overgrazing and loss of livestock on the range. Droughts are a part of the weather pattern in such areas but it is impossible to predict when they will occur. Therefore, in order to be entirely in balance with grazing capacity, numbers of livestock should be somewhat below what the range could graze in an average year, so as to permit accumulation of a reserve of range feed to be available in a drought year. To offset further the effects of drought, reserves of hay or other supplemental feed should be available to carry at least the breeding herd through the drought period. Sharp reduction in numbers through quick sale of lower quality animals is sometimes necessary.
If, as stated, the animal is the end product of forest grazing, attention must be given to the vigor of individual animals, the number and frequency of progeny, and the death losses from starvation and other causes.
In the United States, several different research studies have shown that, when numbers of cattle are in balance with grazing capacity, more beef is produced and a higher dollar return realized per animal than when close grazing is practiced. Similar results have been obtained with sheep and angora goats. In many countries, nomadism and lack of unit area supervision makes control of numbers of animals difficult. In those cases, some more adequate means of range management such as allotment of certain areas to individuals or groups may be needed.
It should be recognized that big game, deer, elk, etc., which graze in the forest constitute a definite part of the grazing load and they should always be included when numbers of animals are being considered for balancing with the forage supply. It should also be recognized that numbers of game animals increase continually and unless they are systematically controlled through hunting or other harvesting methods, they can cause major problems of overgrazing and range deterioration.
Forest values, are, of course, also affected by too many animals but if numbers are in balance with the forage supply and the right kind and breed of animals is being used, the forest values will usually not be seriously damaged by grazing. It is recognized, of course, that certain kinds of trees such as carob, for example, are highly valuable for fodder purposes as well as for wood and can logically be considered a part of the forage supply.
In most grazing areas of the world, some form of seasonal grazing of the ranges is practiced. High mountains are grazed in summer because snow and cold prevent their use at any other time of year. Desert shrub areas which receive only winter precipitation and produce their forage crop in winter are generally grazed in winter, as they are exceedingly dry and bare in summer. The foothills in between are used in the spring and autumn as the livestock move from the low winter ranges to the mountain summer ranges. Such seasonal migrations are logical and, in fact, necessary.
By courtesy of Carocci Buzzi
From an animal nutrition standpoint, the green growing season is the most desirable time to use the forage but in order to plan most effectively for the use of these ranges, consideration should be given to the development and growth requirements of the plants which are most important in the forage supply. The most critical time for removal of the herbage is when the seed-stalks are forming on the plants. Grazing at this time, which is sometimes at the beginning of the summer dry period, means removal of food developed and temporarily stored in the leaves which would normally move to the roots for storage to start the next year's growth. Lack of soil moisture may prevent further growth and production of food material for storage. The management of the range should be planned so as to avoid grazing the same range area year after year at this critical time. Periodic total deferment during this period is desirable. Light grazing early in the season and moderate grazing after maturity of the forage crop will usually maintain the range in good condition.
Many countries could be cited to illustrate the problem of seasonal use and the kind of management which might be desirable to protect and improve the productivity of the range. Certainly, the principles have more or less universal application. For example, in parts of the western United States, there are broad inter-mountain valleys where precipitation is very light and occurs mainly in winter in the form of snow while summers are extremely dry and most of the vegetative growth takes place during the early spring. These ranges are used by either sheep or cattle during the late autumn, winter and early spring. It has been found through research that in order to permit the desirable forage plants to make satisfactory growth, to replenish stored food supplies and to provide seed, grazing during the early spring when the vegetation is making its growth should be restricted to alternate years. This requires that the range be divided into two parts for alternate spring use and that slightly more range must be provided for winter grazing.
The spring range usually lies at the intermediate elevations and the growth period may be somewhat later than on the winter range. Ordinarily, livestock will be using the range during the period of active growth. Here there is great value in a system of deferred and rotation grazing wherein the range may be divided into at least two use units which may be grazed at different times during the spring grazing season. The unit grazed early in the season one year may be grazed late in the season another year so as to avoid any particular unit being grazed during the most critical part of the growing season each year. In many instances, these same ranges may be grazed again in the autumn during the migration to the winter range, so a reserve of forage for use in the autumn should remain at the end of the spring grazing period.
Forage growth on the high altitude summer ranges is still later and livestock graze them many times during much of the growing period. These are usually areas of rather heavy winter precipitation and high soil moisture in early spring, so grazing should be avoided until the soil has become firm and is no longer liable to be trampled or puddled. Plants on the summer range need the same consideration with respect to their growth and development as on the spring-autumn range. Since the summer grazing season often extends considerably beyond the end of the growing season, there is real opportunity to protect plants during the growing seasons on part of the range each year through some system of deferred and rotation grazing.
In some of the high mountain areas of Switzerland, France and Italy, administered by their respective Forest Services, where summer-long precipitation is common, the growth of grasses continues throughout most of the 3 to 4 months' summer grazing season. These pastures are fertilized with manure from the milking shed, and forage production is high. The forage is used similarly to that of cultivated pastures in that the grazing is heavy enough to keep the young green growth available throughout the entire season. Most of these grasses are sod forming, so seed production is not important in the maintenance of their forage production.
In the humid tropics and the warmer parts of the humid temperate zone, the only time the forage can be used to advantage is during the growing season, because its nutritive values become so low at other times. In such humid areas, grazing during the growing season is not as serious as in drier climates because growth is usually much greater than can be utilized. However, the grazing season can sometimes be extended beyond the growing season by the addition of such a protein concentrate as cottonseed meal. The greatest danger lies in overgrazing the important forage species when there may be abundant herbage of less desirable species still remaining on the range.
Broadly speaking, the kind of livestock grazed on a range should be that which can make most profitable use of the forage produced and still protect the other values of the land. Grazing habits and forage preferences vary widely between the various kinds of animals but a particular species of animal has about the same habits regardless of where they may be found. Goats, deer and camels prefer shrubs, trees and other woody types of vegetation and are often referred to as browsers. Goats, particularly, will eat almost any kind of vegetation, but they are often forced to eat many plants in quantity which they would not normally graze. They also use a considerable volume of grasses and other herbs, especially in the spring when such plants are green. In grazing management they are best used on ranges which have an abundance of shrubby plants where it is desirable to keep the amount of brush cover in reasonable balance with other forage so that the land can be used by other livestock, if desired.
When wood for fuel and other forest products are highly valuable on the forest range it is usually best to use animals which do not have preferences for woody types of vegetation. Cattle, buffalo and horses prefer grasses and other herbaceous types of forage. They browse only from necessity and at certain times of the year and often do rather poorly on brush ranges. Sheep and elk also prefer the herbaceous types of forage although in the winter months, when the nutritive values of such vegetation are low, they graze considerably on woody species. It should be emphasized that, with domestic livestock, the breed is fully as important as the kind of livestock using a range. It is not sufficient simply to choose to graze cattle, but if best results are to be obtained a particular breed of cattle must be chosen which is adapted to the conditions of the land where they are to graze. Kind and breed of animal used will vary by conditions of climate, insects, diseases, etc. This is especially important in tropical areas.
Hogs use mast to advantage during short seasons and can be grazed if timber trees are not susceptible to damage. They sometimes injure the roots of certain conifers.
On many ranges, part of the problem of overgrazing is caused by the concentration of animals around watering places, bed-grounds, milking sheds, and in the moist green valleys where the forage may be more succulent and fresh. In reverse manner, there may be parts of the range at a distance from water or otherwise unattractive which could furnish more forage than at present. On many ranges it is virtually impossible to obtain exactly uniform use everywhere but if the over-all number of animals is in balance with the grazing capacity of the range, it is possible to bring about considerable improvement by applying some basic range management practice. To do an effective job it is important to know the characteristics of the range and something of the grazing habits of the animals using the range.
Poor distribution of animals may be due to poor distribution of water for the livestock; rough topography; the presence of so-called sour grass in some parts of the range; the practice of returning flocks or herds to the same central camp night after night; poor control and herding of livestock while grazing on the range; or to concentrations of use caused by trailing, flock migration or nomadism. Not all of these problems of distribution are present on all ranges, in all countries, or all climatic zones, but some of the following practices may be useful in helping to solve them wherever they exist.
1. Develop new watering places for livestock on the range. The principle of scattering livestock in small groups should be kept in mind. Even small watering places which may last only a short time during the grazing season are important.2. Place salt and other minerals which may be deficient in the range forage at strategic places to attract animals into grazing areas normally avoided because of rough topography and other factors.
3. Deliberately herd animals into lightly grazed areas, particularly during times of the year when water and other necessary facilities for grazing animals are available.
4. Practice "bedding-out" or penning in the back country to avoid the effects of trailing to and from the bedding at central camps. The establishment of small, temporary, intermediate camps where the herds are kept only overnight or at most a few days will relieve the main places of concentration.
5. Avoid concentrated movements of livestock such as trailing from one seasonal range to another by planning the grazing and progressive movement of the animals.
6. Improve the palatability of sour grass by prescribed burning and mowing to keep new growth available on the plants. In order to protect the soil and other resources, burning must be well-planned and carefully done during moist periods of the year.
7. Install fences and other range facilities such as milking sheds and shelters for better control of livestock movements. Fences are particularly valuable for dividing ranges into units for control of seasonal use and in implementing plans for deferred and rotation grazing.
An important and basic part of range management is control of livestock and game on the range, so that they will utilize the forage in the most efficient manner possible consistent with the welfare of the forage producing plants and soil. It is emphasized again that, even though the animal is the end product of range use, forage plants and the soil are the basic resources which must be zealously guarded and protected.
A type of grazing management which will guard and protect the forage and soil will also protect the timber and watershed values. With the exception of the hardwood section of the temperate humid zone, grazing and forestry on the same land are quite compatible. In most instances, grazing can continue even under a program of forest range rehabilitation, but the management must be sound and in harmony with requirements of soils and plants to strengthen and rebuild themselves. Grazing can serve to protect the forest by reducing the amount of inflammable material and thereby reduce the fire hazard. Grazing may also aid in the establishment and release of tree reproduction.
All of this, however, does not alter the fact that many forests of the world are virtually unproductive because of the extreme pressure from grazing animals. Before these forests can again be made productive of either wood products or forage, better range management practices must be initiated. In some instances the forest may need to be replanted if there is not a reliable source of seed of desirable species remaining in the old stand. In either event a period of total protection from grazing may be required to give the new stand a chance of establishment.
Better range management in the forest cannot be accomplished simply by talking about it. A country may first need to develop or adopt a definite grazing policy. The policy may have to be supported by legislation and an administrative organization with the power to enforce needed reduction in numbers of livestock, particularly of certain kinds which may be harmful to the forest trees, and make a start toward proper seasons of use. In the meantime, people must be convinced of the necessity and value of such a program so that they will co-operate in its execution. Without the backing and co-operation of the users of the land, forest and range improvement is indeed difficult.
