Introduction
•Humans need food as a source of energy and for tissue replacement, like any other animal. The source of much of the food consumed by man is terrestrial agriculture.
•This represents the most manipulated of all the non-urban ecosystems, in which the energy and matter pathways are directed almost entirely to man and where he maintains a high level of input of matter and energy to keep the system stable in order to yield his preferred crop.
•Not only is the ecosystem man-made, but the plant and animal components of it have usually been genetically altered by man in the course of their domestication.
There are two main types of agriculture.
•crop agriculture, in which plant production is harvested for use by man either directly or after processing and animal agriculture, where a crop from highly manipulated ecosystem is fed to domesticated animals.
•Ecologically, terrestrial agriculture presents man either as an herbivore or as a third trophic level carnivore.
•Terrestrial agriculture systems today exhibit a major division into shifting and sedentary types:
•(i) Shifting Cultivation
•In shifting cultivation, total manipulation of the natural system is practised over a limited area but for only a short (1–5 years) period of time.
•Thus, the agricultural path is spatially and temporarily enclosed by wild vegetation. Today, shifting cultivation is largely confined to tropical forests, savannas, and grasslands.
•In this type of cultivation crops are planted in a mosaic of different heights and times of fruition so that the plant cover of the soil remains as complete as possible throughout the year in order to reduce the leaching effect of heavy rain fall.
•Slash and burn’ techniques provide mineral nutrients for their uptake by the crops.
•The natural diversity of the forests is imitated by the variety of crops which are grown by some shifting cultivators.
•For example, the tropic crops of Hanuni of the Philippines include rice, beans, root crops, shrub, legumes, tree crops, yam, taro, sweet potato, vines, bananas and sugarcane, together with European-contact crops such as maize, ground nuts, tomatoes, melons and pumpkins.
•Ecologists have found shifting cultivation as a well-adapted system in forested lands where the trees regenerate easily when the plots are deserted, and where an equilibrium population has established.
•(ii) Sedentary Cultivation
•Sedentary cultivation represents the permanent manipulation of an ecosystem ; the natural biota are removed and replaced with domesticated plants and animals.
•Competition by the remnants of the original biota or by man-introduced organisms may still remain and considerable efforts may be needed to keep these weeds and pests at an acceptable level.
•In dry land agriculture the soil assumes an importance for it now becomes the long-term reservoir of all nutrients and is constantly depleted as crops are harvested and removed. The nutrients must be replenished either by the addition of organic excreta or chemical fertilizers.
•There is also the paddy-culture of rice, where the soil is very largely a mechanical rooting medium for the plants and the water supplies the essential mineral nutrients ; it often contains blue-green algae which fix nitrogen, for example.
•The variety of crops grown under the various forms of sedentary cultivation is very high and changing patterns of agriculture together with shifting trade flows and altered rates of consumption make a world kaleidoscope of infinite variety.
Green Revolution
•Due to application of ecologically sound principles agriculture has resulted into Green Revolution, i.e., increased agriculture production.
•In fact, the Green Revolution of the late 1960s, was based on new genetic strain of rice and wheat, improved irrigation, and better application of fertilizers and it has achieved a doubling and tripling of crop yields in many tropical countries.
•But recently, Green Revolution has exhibited certain ecological problems—the breakdown of soil structure in European countries under a regime of continuous cereal cropping with the use of physically heavy machinery and its increase dependence upon petroleum and fertilizer.
New Sources of Food
•Most modern ecologists hold the view that even if the rapid development of conventional agriculture is sustained, protein deficiencies will continue to exist (Simmons, 1974).
•A search for supplementary sources of plant and animal proteins is, therefore, in progress. Animal proteins are more preferred ones because their amino-acid make-up is closest to man’s requirements.
•Animal flesh has the further advantage that it is usually the more easily assimilable, since the plant proteins are locked away behind a cell wall of cellulose not easily broken down by the action of the human stomach.
•Animals, thus, have been a means of harvesting the plant protein in a digestible form, and so have considerable dietary advantages.
•Animals retain many desirable characteristics as cellulose-converters and as saliva-inducers.
•As very small number of wild animals have been domesticated by man for milk, wool, skin, food, transportation, etc., recently, certain other wild animals are increasingly domesticated.
•Birds such as young colonial seabirds, reptiles, amphibians, insects, crustaceans, molluscans, rodents, and many other animals can be utilized as food.
•Freshwater and brackish-water fish are other sources of animal proteins. Marine and freshwater fisheries provide a best source of animal proteins.
•Fungi appear to be easily assimilated and contain a good deal of protein by comparison with some other sources such as beef, fish, etc.
•Other advantages of mushrooms are that they do not absorb much human or fossil energy in production, can be grown independently of environmental factors in places such as caves and abandoned railway tunnels, can readily be stored in dried form and require little sophisticated knowledge or technology.
•Due to overfishing of certain favourite fish species, recently following trends are adopted for continuous abundant supply of fishes :
•(i) Extension of fisheries. The fisheries have been extended from three sources : the utilization of untapped species, the cropping of hitherto unattractive areas, and the development of more novel methods of culture and harvesting.
•During recent years many new fisheries have started to flourish, such as Peruvian anchoveta, Alaska pollock, Bering Sea flatfishes and herring, and several more. In future, fishing method may be extended in the cool temperate parts of southern hemisphere. (ii) Krill. Uneaten food of whales is also found suitable for human consumption as food. Approximately 80 per cent of the prey of blue and fin whales is krill, the shrimp Euphrasia superba, each of which contains 7% fat and 16% protein.
•iii) Aquaculture.
•To increase the yield of certain edible species of freshwater and marine fishes, molluscs and crustaceans and other aquatic organisms, fish farming or aquaculture that includes their culturing and herding, has been employed and at a commercial scale.
•Framework are lowered into shallow offshore waters and allowed to colonize with sedentary molluscans like oysters and mussels with sense species, the individuals grow on ropes that hang clear of the action so that they are out of the reach of predators such as starfish. Although productive, such systems are very vulnerable to contamination, and since the organisms filter large quantities of water their ability to concentrate substances toxic either to themselves or to consumers is very
Livestock as renewable resource
•The branch of agriculture which is mainly concerned with the breeding, feeding and caring of domestic animals is called animal husbandry.
•When it incorporates the study of proper utilization of economically important domestic animals, it is called livestock management. Livestock (viz., cattle, buffaloes, sheep, goats, pigs, camels, horses, donkeys, mules (ponies), etc.,) form an important renewable resource, as they provide milk, eggs, meat, skin (leather), horn, dung and other products.
•The total livestock in India amount to a huge population consisting of 185 million cattle, 97 million goats, 61 million buffaloes, 45 million sheep, 1 million horses and ponies.
•1 million camels and about 1 million other livestock. There are also 156 million poultry (fowls) and other domestic birds (such as ducks, turkeys, etc.). All these provide 1 million tonnes of meat, 40 million tonnes of milk, 39 million kg of wool and 13 million eggs.
•The amount of dung produced is enormous and is used for biogas production and as manure. Livestock is also used for rural transport and agriculture. Therefore, to get a sustained yield from them, their proper breeding, health care and management and diet are essential.
FOREST Resources
•Forests occupy a special place in the life and thought of the people.
•They form an important A domestic ‘biogas’ digester in an Indian village, using animal manure and producing methane for cooking and heating water renewable natural resource. Forest ecosystem is dominated by trees, their species-content varying in different parts of the world. Forests contribute essentially to the economic development of our country by providing goods and services to the people and industry.
•They are intimately linked with our culture and civilization. The chief products that forests supply is wood which is used as fuel;
•raw materials for various industries as pulp, paper, news-print, board, plywood;
•Timber for furniture items, toys, sports goods, musical instruments, wooden crates, boxes (for packing articles for fruit, tea, etc.), boats, truck bodies, carts, ploughs, railway sleepers, bridges, buildings; fodder for cattle’s, sheep, goats and camels and bamboos.
•Bamboos, called poor man’s timber, are used in rafters, scaffolding, roofing, walling, flooring, basketry, cart wood and cordage. Industrially bamboos are used as a raw material in paper and rayon industry.
•Tendu (kendo) leaves are used as wrappers for bidis, soap-substitutes such as Retha and shikakai, sola pith and ornamental seeds Rud Raksha are important commercial products of the forests.
•Lac, honey, wax, tusser or Moga silk are obtained from forest insects. Feathers, horns, hides and ivory are also other significant forest product (obtained from forest wildlife).
•Besides above discussed uses, forests are also a major factor of environmental concern, providing protection to wild life, help in gaseous (i.e., CO2, O2) cycles of atmosphere, tend to enhance local rainfall and water holding capacity of soil, maintain the soil fertility, regulate the earth’s temperature regimes and water cycle, check soil erosion, landslides, shifting of sand and silting and reduce the flood havoc.
•Forests play an important role in reducing atmospheric pollution by collecting the suspended particulate matter and by absorbing carbon dioxide. Lastly, forests have aesthetic and touristic values and serve as gene reserve of important species.
Deforestation (Destruction of Forests)
•Deforestation is an alarming threat to the economy, quality of life and future of the environment.
•The main causes of the deforestation are :
•Explosion of human and livestock population, increased require-ment of timber and fuel wood,
•Expansion of croplands
•Enhanced grazing prominent causes of forest destruction are construction of roads along the mountain (hill roads),
•Dam building (valley projects) ever migrating grazers.
•Shifting (jhum) cultivation, agriculturalization, urbanization and industrialization.
•Stress on revenue earning and resources regeneration for pulp and match industries seems to have accelerated soil erosion. Resin tapping from chirr-pine trees has choked the trees to death.
•The devastating effects of deforestation include soil, water and wind erosions.
•Deforestation has a major impact on the productivity of our croplands.
•This happens in two ways :
•(i) soil erosion increases manifold and the soil actually gets washed, leading to an intensified cycle of floods and drought.
•(ii) the shortage of firewood has an obvious impact on the productivity of our croplands. Thus, when firewood becomes scarce, people begin to use cattle dung and crop wastes as fuel, mainly for cooking. In a way, every part of the plant gets used up gradually and goes back to the soil.
•Over a period of time, such a nutrient drain affects crop productivity due to loss in soil fertility. Further, the local cattle’s, goats, sheep, etc., not only destroy the vegetation but also pull out the roots of the plants.
•Destruction of biotic potential of land also leads to desertification. Desertification is the process leading to desert formation.
•Removal of vegetal cover brings about marked changes in the local climates of the area.
•Thus, deforestation, overgrazing, etc., bring about changes in rainfall, temperature, wind velocity, etc., and also leads to soil erosion.
Afforestation
•A. Conservation or Protective Forestry
•This includes the following three strategies :
•(a) Conservation or reserve forests. These forests are the areas where our water regimes are Several trees are cut every year for firewood which is a major cause of deforestation located (e.g., Himalayas and Western and Eastern Ghats together with catchment areas). They also include National Parks, Sanctuaries, Sacred Groves, Biosphere Reserves and all ecologically fragile areas. In these areas, no commercial exploitation can be allowed.
•b) Limited production forests. These are less fertile areas at more than 1000 meters altitude with hilly topography. A part of the annual growth may be harvested in a very careful and controlled manner so as to avoid soil and tree damage. (c) Production forests. Such types of forests lie on the flat land and are managed for high degree of production. Their working on scientific lines with proper logging methods does not pose environmental problems.
•B. Commercial or Exploitative Forestry
•The basic aim of commercial forestry is to supply goods and services and meet the needs of local people for firewood, fodder, food, fertilizer, fiber, timber, medicines, etc.
•These forests also supply material for industrial purposes as timber of all types, plywood, matchwood, fiber board, paper and pulp, rayon, Silvi chemicals, etc.
•This can be achieved by
•(i) intensive plantation
•(ii) captive plantations
•i) Intensive plantations.
•This type of forestry includes planting all the available land from villager’s fields to commercial land, to road/rail sides and every available space. For removing pressure on the natural forests, indigenous and/or exotic species can be used for plantation. Intensive plantations include two types of programmed : social forestry and agro-forestry.
•a) Social forestry.
•Social forestry envisages use of community lands, individual holdings and other public lands, denuded/degraded lands for producing what the dependent rural and tribal communities need and for environmental purposes.
•There are two main objectives in social forestry :
•1. use of public and common land to produce in a decentralised way fire wood, fodder and timber for the local poor men and also to manage soil and water conservation.
•2. to relieve pressure on conservation forests.
•(b) Captive or Production plantations (Agro-forestry).
•This is absolutely commercial forestry which is developed to fulfil the needs of the various forest-based industries requiring large quantities of raw materials.
•The captive plantation is done on the fallow land, which is not being used for agriculture, mostly on free grazing lands. A part of this plantation is used to produce fodder for the cattle.
•Further, in this type of plantation, short rotation of indigenous or exotic species is preferred over long duration Sal or teak.
Measures for the conservation forestry
•Following strategy can be adopted to prevent further depletion of tree cover in the conservation forests :
•1. Extraction of timber should not interfere with watershed protection. Tree-felling should be matched with tree-planting programmes.
•2. The use of firewood should be discouraged to reduce pressure on more valuable natural forests. Other sources of energy such as biogas, solar energy, etc., have to be provided to supplement practices.
•3. A better understanding should be developed between the persons who manage and those utilising trees. Thus, there is a growing need for
•(i) creating a new cadre of forest managers and barefoot foresters committed to conservation.
•(ii) involvement of rural/tribal people in forestry programmes
•(iii) encouraging industries using forest products to obtain raw material at market price and help them to raise plantations much in advance to meet their demands.
•4. Forest dwellers should have access to subsidised sources of fuel, fodder, building material, etc., so that they do not cut forest trees.
•5. A ban or freeze (i.e., moratorium) of 15 to 20 years should be imposed on commercial tree fellings in fragile areas of Himalayas and other hilly areas.
•6. During moratorium, an extensive afforestation programme with people’s participation should be followed.
•7. Environmentally sound action plans based on scientific research should be adopted.
•8. By the help of people’s cooperatives, community forests should be developed around villages.
•9. Protection of standing forests should be done.
•10. Creation of new stock should be made.
•11. Masses and voluntary agencies should be involved in the task of tree planting.
•12. Building of information base have to be made.
•Forest conservation through law.
•The National Forest policy 1952 stated that one third of the geographical area of the country should be under forest. Forest (Conservation) Act, 1980 was enacted with a view to check indiscriminate DE reservation and diversion of forest land to non-forest purposes. This act was amended in 1988 to incorporate stricter panel provisions against violators.
RANGE MANAGEMENT (GRASSLAND MANAGEMENT)
•Grassland biomes are important to maintain the crops of many domesticated and wild herbivorous mammals such as horses, mules, asses, cattle, pigs, sheep’s, goats, buffaloes, camels, deer’s, zebras, etc., all of which provide food, milk, wool, hide, or transportation, etc., to man.
•The range management involves an important application of ecological principles in maintaining the grassland biomes.
•The objective here is to preserve grasslands for maximum forage, i.e., food for cattle.
•During range management a suitable degree of grazing is to be maintained.
•Some species are more palatable to the stock and are very sensitive for grazing and, thus, overgrazing usually results into their disappearance from the area where now some unpalatable, annuals, weeds, shrubs start to grow and turn the area into man-made desert.
•The palatable plant species, which are sensitive to grazing, have been called the decreases whose disappearance from the area is an indicator of grazing stress and warning signal for range managers.
•Overgrazing has certain other ecological effects—reduction of the mulch cover of the soil occur, microclimate becomes more dry and severe and is readily invaded by xerophytic plants.
•Due to absence of humus cover, mineral soil surface is heavily trampled when wet and produces puddling of the surface layers, which in turn reduces the infiltration of water into the soil and accelerates its runoff, producing drought.
•These changes all contribute to the reduction of the rate of energy flow, and the disruption of the stratification and periodicity of the primary producers results in a breakdown of the biogeochemical cycles of water, carbon and nitrogen.
•Water and wind erosion completely breakdown a very dry grassland-microclimate.
•Further, intensive grazing which results in increased areas of bare soil, creates a new habitat for burrowing animals such as mice, jackrabbits, gophers, prairie dogs, locusts, etc., which render sterile many areas of forage lands.
•In range management, fire, plays an important role. Under moist conditions fire favors grass over trees and under dry conditions fire is often necessary to maintain grasslands against the invasion of desert shrubs. Burning of Cynodont dactylion increases forage yields
LAND USE PLANNING AND MANAGEMENT
•Land is a precious resource, since it is put to diverse use by man. India with a land area of 32,88000 km2 which is about 2.4% of the world supports 15% of the world’s population.
•There were about 238 million people in India in the year 1901 and are now about 850 million. The per capita land resource available now in India is less than 0.4 hectares, in comparison to more than 0.9 hectare in China and about 8.4 hectares in the USSR.
•About 44% of our land is used for agriculture, 23% is covered with forests, 4% is used for pastures and grazing fields, 8% for housing, agroforestry, industrial areas, roads and so on. The 14% land is barren and about 8% is used for miscellaneous purposes.
•The rapid increase of urbanization and migration of population from rural areas to towns and cities has created many problems. All this has led to the utilization of agricultural land for housing, construction of office buildings, industries, and so forth.
•The rational use of land resource is possible by adopting an integrated land-use policy which involves prevention of land misuse and reclamation of degraded and under-utilized land, wastelands, fallows, etc.
•Reclamation of abandoned mines and brick kilns may yield some much required land.
•Fertile agricultural land should not be sacrificed for non-agricultural purposes, such as road building, development of industries or construction of water reservoirs.
•Urban areas should not be developed on agricultural lands.