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Range management defined
Range management is the manipulation of rangeland components to obtain the optimum combination of Goods and services for society on a sustained basis. Range management has two basic component; (1 Protection and enhancement of the soil and vegetation complex, and(2) maintaining or improving the Output of consumable range products , such as red meat , fiber , wood , and wildlife.
The range management profession is unique among agricultural vocations in that it deals with the plant And animal interface rather than dealing with plants or animals in isolation. The distinguishing feature of range management
In that it deals with manipulating the grazing activities by large herbivores so that both plant and animal production will be maintained or improved . rang management is based on five basic concept :
- Rangeland is a renewable resource .
- Energy from the sun can be captured by green plants that can only be harvested by the grazing animal.
- Rangelands supply humans with food and fiber at very low energy costs compared to those associated with cultivation lands .Ruminant animals are best adapted to use range plants . Unlike human beings , ruminants have microbes in their digestive system that efficiently beak down fiber which is quite high in most rang plants .
- Rangeland productivity is determined by soil , topographic and climatic characteristics .
- A Varity of ‘ products ‘ including flood , water , recreation , wildlife , minerals and timber are harvested from rangeland .
Relation of range management to other disciplines
Range management is distinct from other disciplines in that it integrates into a unified system knowledge from several disciplines . the basic components of range management can be recognized in to biological , physical and anthropological factors . initially range manageress were concerned primarily with the biological components , particularly plant because plant communities are the primary producers of flood for grazing animals . because plant productivity depend on interaction between climate and soils as well as grazing influences , the additional need to understand the physical environment became apparent . Since range management is grated toward producing products usable to man ,social, economic ,cultural ,and technological consideration are a critical part of range managment decision- making process.
The importance of rangeland to Humans
Many scientists consider the most pressing problem confronting human kind to be the tremendous increase in the human population expected in the next 50 years. The fall off in population growth rate has com almost exclusively from developed countries . Birthrates remain high in developing countries. In developed countries ,food production has kept far ahead of population growth rate but in many developing countries food shortages remain an important problem and this is expected to continue for future decades.
Trends in human population growth and economic development will have considerable influence on how rangelands in various countries will be used in coming years. (Although the emphasis may shift among rangeland products , the expansion in the human population will undoubtly make rangelands more important to human kind than before.
Rangeland are the primary habitat for nearly all the land dwelling wild animal s highly valued for meat, hunting and aesthetic viewing .the economic value of wildlife on rangelands is becoming increasingly recognized in developed and developing countries .in some developed countries ,income generated frome selling hunting privileges can exceed that from livestock on some ranches.hn some developing countries also ,income from tourists viewing wildlife hs of critical importance to the national economy.
Water hs the major problem confronting many countries .this is due not only to rapid growth in human population but also to the depletion of ground water reserves at an ever _ increasing rate .on most arid to semiarid rangeland ,rang management practices have been and will continue to be geared toward improving water retention on the site ,thus reducing sedimentation and improving recharge of the water table .on forested and alpine rangelands considerable potential exists for increasing yields from overland flow by vegetation modification through logging and grazing practices.
The large human population increases in the world have made rangelands increasingly important as places for people to engage in outdoor recreational pursuits.hiking,camping,trailbiking,picnicking,huntingfishing,and rock hounding are some of the important recreational uses of rangeland.
lands. Ranchers are finding more opportunity to market recreational values from rangelands. Marketable recreational products include hunting, fishing and camping privileges, horse back riding, and home sites.
Rangelands produce a wide variety of plants that could be very important in meeting our future needs. Salt tolerant shrubs such as Atriplex canesens have considerable potential to be productive forage species on lands with prolonged drought and excessive salinity. Many rangeland shrubs are being developed and used for landscaping purposes. Some of desert shrubs contains rubber that can be used for tires, medical supplies, and other items. Some of desert forbs and shrubs contain substances that may inhibit cancer growth and have other medical properties. Many range land plants have the potential to be developed in to valuable domestic food and forages species using new genetic engineering techniques.
Wood and Minerals
Wood and minerals are important products from some rangelands. Decisions regarding the use of minerals are usually made by geologists, and grazing management has little effect on this rangeland resource Timber, livestock, and wildlife production occur concurrently on many rangelands. Grazing by livestock can influence timber production. It is therefore essential that both the forester and range manager understand interrelationships between grazing and timber management.
The rangeland physical characteristics
A thorough knowledge of rangeland physical characteristics is essential for understanding of rang manegment problems The physical characteristics include climate ,soil, and topography. physical characteristics determine the type of vegetation and its productivity in any area.
Precipitation is the most important factor determining the type and productivity of vegetation in an area. Forage production increase up to about 500 mm of precipitation per year , soil characteristics can assume Much greater importance than precipitation in determining forage production. Critical characteristics of Precipitation that affect vegetation are the total amount , the distribution, the relative humidity, the form ,and the annual variability.
Annual variation in precipitation
The lower anoanl of precipitation that charactericse most rangelands is made more sever by the greate Year to year variability. The variability in precipitation increases rapidly as the annual total drops below 450 mm per year . even slight reduction from normal precipitation can cause sever reduction in plant yield in areas below 300mm of precipitation while greater reduction in precipitation may have no influence on plant yield in areas with over 800 mm of precipitation.
Drought is defined as prolonged dry weather ,generally when precipitation is less than 75% average annual amount. drough has a tremendous in flounce on rangeland vegetation .some important range species may eliminate under the drought condition .two or more consecutive years of drought followed by normal or above normal precipitation. although light to moderate grazing may improve a plantۥs ability to withstand drought, heavy grazing during and after drought years reduces plant cover and productivity.
Wind can substantially reduce precipitation effectiveness by increasing soil evaporation losses and increasing plant transpiration .wind has little influence on soil moisture below 20 cm to 30 cm and highest wind velocities occur in flat terrain with few trees .hot summer winds during dry years greatly magnify the effect of drought by increasing both soil moisture losses and plant transpiration .cold windy springs generally result in poor forage production even though winter and spring precipitation may be above average .much of precipitation may be lost from the soil surface before temperatures are warm enough for significant plant growth.
Temperature for different seasons and years vary substantially on rangeland in temperate zones .in tropical areas, monthly and yearly Temperatures show little variation. In mountainous areas temperature can have as much influence on annual variation in forage production as does precipitation. Nearly all forage species in these regions are cool season and most of their growth occurs in the spring. therefore years with above average spring temperatures are usually characterized by above-average forage production even though total precipitation may be below average.
Humidity refers to the amount of moisture in the air. It is usually expressed as relative humidity which is the percentage of the maximum quantity of moisture that air can hold at prevailing temperature. Cold air can hold less moisture than warm air .water evaporation from the soil and plant transpiration losses increases as the relative humidity decreases. Therefore areas with high humidity give grater plant growth per unit of precipitation than do areas where humidity is low.
Topography influences precipitation because air masses cool as they move upward over mountains .this is called orographic effect. condensation and precipitation occur because cool air can hold less moisture than can warmer air. Areas on the leeward side of mountains are usually guite dry. This is because air masses descending mountain slopes lose much of their moisture during ascent ,and they can hold move moisture as they warm with decreased elevation. Because of the orographic effect precipitation generally increases with elevation, therefore low- elevation ranges typically produce much less vegetation than do those high elevation.
Soil is defined as the dynamic, natural body of the surface of the earth in which plants grow. Soil formation is a very slow process; a thousand years or more are required to form an inch of soil. Soil is comprised of minerals, organic materials, and living forms. Soil is distinguished form regolith (unconsolidated rock and materials ) by a higher organic matter content, more intense weathering, the presence of horizontal layers, and the presence of living organisms.
Soil characteristics of important to the range manager include texture, structure, depth, PH, organic matter content and mineral status (fertility).
Soil texture refers to the size of mineral particles comprising the soil. Soil textural sizes from the smallest to largest are clay, silt, fine sand, fine gravel and coarse gravel. Based on the proportions of these particle size, a soil can be classed as sand, loamy sand, sandy loam, silt loam, clay loam or clay. To a considerable degree, soil texture determines the fertility of the soil. Soil with a high clay content retain nutrients such as nitrogen, phosphorus and potassium compounds much better than do sands. This is because the small particles have a much greater total surface area for attracting and binding nutrients per unit volume than do large particles. Soil texture also plays an important role in soil moisture status. Water enters coarse, sandy soils much more rapidly than fine clay because there is more space between particles. On the other hand, clay soils retain water much better than do sandy soils. The best balance between moisture infiltration and retention is obtained with loamy soils which have a mixture of sand, silt, and clay.
Soil structure refers to how soil particles are arranged . soil structure is quite important since it determines the rate at which water can enter the soil . there are six basic types of soil structure : plate like , prism like , spheroidal , single grained , and massive . a massive soil structure is tightly compacted with little or no space between soil particles for infiltration . single grained structure refers to a loose arrangement of individual soil particles that do not stick together such as sand . plat like structure refers to soil particles aggregated together in to leafy plates . this type of structure can result naturally from parent material or soil forming forces . infiltration is minimized with this type of structure . prism like structure refers to soil particles aggregated in vertical columns . when the tops are round , this type of structure refers to columnar . the spheroidal structured soil have the best characteristics for water infiltration and storage . the aggregates are round and easily shaken apart . soils high in organic matter usually have a spheroidal structure.
Soil depth has considerable influence on soil productivity since it determines how much moisture the soil can hold . a deep soil in an area with moderate precipitation will often produce more forage than a thin soil receiving heavy precipitation conversely , in some arid areas on thin , sandy soils underline with a hard impermeable layer are more productive than grasses on deeper sandy soils . the impermeable layer restvics moisture to the portion of the soil profile near the surface where it can readily be used by fibrous roots of the grasses . depth usually means distance from the soil surface to bedrock or unconsolidated material . soil depth , in conjunction with texture and structure largely determines the potential of a site for cultivation.
Soil pH indicates the status of the soil in regard to exchangeable mineral ions, The pH value expresses whether soil is basic or acidic . A high – acid soil would have a pH of 4, while a highly soil would have a pH of 10 or more. The scale ranges form 1 to 14. minerals are most available to plants in soils with pH values between 6 and 8 . A pH value of 7 is considered ideal for growth of most plants. However, many species of plants grow best where soils are either highly acidic or basic . The low rain fall result in little leaching of soil. Leaching refers to down washing of soil minerals from precipitation. Oxisoils are the most heavily leached soils in the world.
Soil organic matter represents an acculation of partially decayed and partially synthesized plant and animal residues .It represents a relatively small part of the soil and is found primarily in the upper 30cm of soil. partially decomposed organic matter that has been incorporated in to the soil called humus . Humus provide a constant although small supply of nutrients to plants. More important it as a binding site for cations and prevents them from leaching out of the soil profile. other important functions of human include binding of soil particles together , increasing soil moisture-holding capacity and providing food for microorganisms .
Next to water, fertility is second most limiting factor to forage production in arid rangelands with less than 500mm precipitation. On high –rain fall rangelands soil fertility is usually the most limiting factor to forage production. Nitrogen is the most deficient element in rangeland soil from the stand point of plant growth. Rangeland soils in high –rain fall areas are heavily leached and have low levels of elements required by animals. Forages growing on these soils often have in adequate levels of these elements to meet livestock requirements. Low soil fertility is a major problem limiting forage and livestock production in many rangelands.
Water is the primary limiting factor to plant production on most rangelands of the world. All water used rangelands is derived from precipitation. A portion of the precipitation moves laterally off the site to streams ,lakes, ponds, reservoirs ,and oceans . This water is referred to as surface runoff or overland flow. Another portion is retained on the site by the process of infiltration (movement of the water in soil profile) and becomes available for plant growth .part of moisture infiltration the soil moves deep below the soil surface and recharge under ground water supplies that save as sources for wells, seeps, springs, and streams. the major portion of precipitation(about 70%) received on rangeland evaporates and return to the atmospheres as water vapor.
The hydrologic cycle
The process by which energy from the sun causes water from the land and oceans to vaporize in to the atmosphere ,condense , as the result of cooling due to uplift and-or movement over land and return to the earth as precipitation is termed the hydrologic cycle. The primary source of moisture in the air is from oceans. Other important sources are from transpiration (moisture released from plant parts, mainly leaves ) and evaporation from streams, lakes, and land surfaces. Man can influence the hydrologic cycle by modification of vegetation and soil.
After a raindrop reaches the soil surface, it can infiltrate the soil, evaporate, or become a part of overland flow. Once in the soil, water movement is defined as percolation. The primary factors influencing infiltration rate are intensity of precipitation amount and kind of vegetation cover, and soil surface properties(texture, structure, and organic matter). When infiltration is high, much of the precipitation, is stored in the soil for plant use, and part of it may penetrate to groundwater, where it can be recovered from springs or wells. Conversely, high rates of surface runoff contribute to soil loss and flooding. Fine textured soils (clays) generally have lower infiltration rates than do coarse textured soils (sands). However, some fine-textured soils have infiltration rates comparable to those of coarse texture. This is due to commenting of the fine particles in to aggregates that act like larger particles.
The primary factor influencing infiltration that range managers can control is vegetation cover. When rain drops fall on unprotected soil, they dislodge soil particles and remove the soil surface. As plant cover declines, infiltration decreases. This reduces soil moisture available for forage production, and contributes to desertification of arid areas. Water repellency has been recognized in many soils. It affects the hydrologic cycle by reducing infiltration rates. Water repellent soils are present with and without burning. But they are often associated with a burn. On burned watershed the water repellent layer occurs just below the surface of the soil. The thickness of the layer depends on the intensity of the fire and amount of mulch.
Runoff and Erosion
Surface runoff is imitated when the amount of precipitation exceeds the infiltration and storage capacity of the soils. The primary factor influencing runoff is the amount of vegetation available to retard water movement over the soil surface. Runoff declines as soil cover increases. Erosion and sediment (suspended minerals materials in water) deposition are major problems caused by excessive runoff. Maximum sediment yields occur at about 250mm of annual precipitation. A decrease occurs below 250mm precipitation because of lake of runoff to transport the sediment. About 250mm precipitation decrease is due to increased cover of vegetation. Sediment is economically significant because it is determinanly deposited on land and plants, reducers servoir storage capacities, causes increased flood hazard and pollutes stored water supplies.
Geologic erosion is normal erosion for a natural environment undisturbed by Construction, can cause accelerated erosion, which proceeds at a higher rate than normal geologic erosion. Differentiating the two types of erosion is a challenging problem .rangelands often have high rates of geologic erosion because of steep slopes, aridity, thin soils, and a sparse vegetation cover. Accelerated erosion occurs when mans activities destroy the vegetation cover that retards soil loss from the forces of water and wind. The invers relation ship between accelerated erosion and plant cover is well established. Accelerated erosion is is the most sever consequence of over grazing due to the fact that replenishment of lost soil is a slow process. Several handered years are required to form an inch of soil, therefore, losses of soil result in nearly permanent reductions in grazing capacity. The best protection against erosion is to establish and maintain a good vegetative cover. During the initial phases, changes in grazing management can often bring accelerated erosion under control. However, in the more enhanced stages, costly measures such as mechanical structures and revegetation are often necessary.
Manipulation of Water Yield
The major objective of most mechanical rangeland treatment is to improve vegetative production by increasing moisture storage and reducing soil erosion. Soil characteristics, climate, type of vegetation, and equipment are the principle variable that determine treatment impact on any watershed.
Contour Tranches and Farrow
Contour tranches were initially applied on rangeland for controlling flood and soil erosion in northern Utha. The principle of contour trenching – to retain water on the site where precipitation occurs, thus preventing overland flow, erosion, and sedimentation—has proved effective and many eroded flood source areas have been trenched. Contour farrows differ from trenches in being narrower and shallower.
Pitting and Ripping
Pitting consists of forming small basins or pits on the catch and hold precipitation and runoff water. Ripping is used to shatter compacted soil profiles that inhibit moisture penetration and root development. Ripping to a depth of 3cm to 90cm has been effective in improving vegetation composition and productivity in the short grass prairie.
Water spreading is a technique that involve diversion water drainage on to the surrounding landscape through a system of dikes, dams, or ditches. The diversion of runoff water with earthen banks to areas to favorable for cultivation dates back to early inhabitants of middle east and south America. Water spreading on rangelands has three main function: (1)increasing forage production by spreading of flood water,(2)reducing erosion in drainage ways, and (3)reducing down stream flooding and sedimentation. Stream channel (dry most of the time but flowing for short periods ) generally provide the water supply for water spreading schemes. Water spreading has been used in Australia to reclaim bare areas.