From Ecosystems to Global Biomes An ecosystem is a grouping of plants, animals, and microbes occupying an explicit unit of space and interacting with each other and their environment. Thus, a forest, a grassland, a wetland, a marsh, a pond, a sand dune, and a coral reef, each with its respective species in a particular environment, can be studied as distinct ecosystems. Similar or related ecosystems are often grouped together to form major kinds of ecosystems called biomes. Tropical rainforests, grasslands, and deserts are biomes. While more extensive than an ecosystem in its breadth and complexity, a biome is still basically a distinct type of biotic community supported and limited by certain abiotic environmental factors. We can now use the concepts of optimums and limiting factors to gain a better understanding of why different regions or even localized areas may have distinct biotic communities, creating an amazing variety of ecosystems, landscapes, and biomes. The Role of Climate The climate of a given region is a description of the average temperature and precipitation - the weather that may be expected on each day throughout the entire year. Climates in different parts of the world vary widely. Equatorial regions are continuously warm, with high rainfall and no discernible seasons. Above and below the equator, temperatures become increasingly seasonal (characterized by warm or hot summers and cool or cold winters); the farther we go toward the poles, the longer and colder the winters become, until at the poles it is perpetually winterlike. Likewise, colder temperatures are found at higher elevations, so that there are even snowcapped mountains on or near the equator. Annual precipitation in any area also may vary greatly, from virtually zero to well over 100 inches (250 cm) per year. Precipitation may be evenly distributed throughout the year or concentrated in certain months, dividing the year into wet and dry seasons. Different temperature and rainfall conditions may occur in almost any combination, yielding a wide variety of climates. In turn, a given climate will support only those species that find the temperature and precipitation levels optimal or at least within their ranges of tolerance. Population densities will be greatest where conditions are optimal and will decrease as any condition departs from the optimum. A species will be excluded from a region (or local areas) where any condition is beyond its limit of tolerance. Biome Examples. To illustrate, let us consider six major types of biomes and their global distribution. Table 2- 3 describes these terrestrial biomes and their major characteristics, and Figure 2-19 shows the distribution of, and variations in, the biomes as they occur globally. Within the temperate zone (between 30° and 50° of latitude), the amount of ra infall is the key limiting factor. The temperate deciduous forest biome is found where annual precipitation is 30-80 in. (75 -200 cm). Where rainfall tapers off or is highly seasonal (10-60 in., or 25-150 cm, per year), grassland and prairie biomes are found, and regions receiving an average of less than 10 inches (25 cm) per year are occupied by a desert biome. The effect of temperature, the other dominant parameter of climate, is largely superimposed on that of rainfall. That is, 30 inches (75 cm) or more of rainfall per year will usually support a forest, but temperature will determine the kind of forest. For example, broad-leafed evergreen species, which are extremely vigorous and fast growing, but cannot tolerate freezing

temperatures, predominate in the tropical rain forest. By dropping their leaves and becoming dormant each autumn, deciduous trees are well adapted to freezing temperatures. Therefore, wherever rainfall is sufficient, deciduous forests predominate in temperate latitudes. Most deciduous trees, however, cannot tolerate the extremely harsh winters and short summers that occur at higher latitudes and higher elevations. Therefore, northern regions and high elevations are occupied by the coniferous forest biome, because conifers are better adapted to those conditions. Temperature by itself limits forests only when it becomes low enough to cause permafrost (permanently frozen subsoil). Permafrost prevents the growth of trees, because roots cannot penetrate deeply enough to provide adequate support. However, a number of grasses, clovers, and other small flowering plants can grow in the topsoil above permafrost. Consequently, where permafrost sets in, the coniferous forest biome gives way to the tundra biome (Table 2-3). At still colder temperatures, the tundra gives way to permanent snow and ice cover. The same relationship of rainfall effects being primary and temperature effects secondary applies in deserts. Any region receiving less than about 10 inches (25 cm) of rain per year will be a desert, but the unique plant and animal species found in hot deserts are different from those found in cold deserts. A summary of the relationship between biomes, and temperature and rainfall conditions, is given in Figure 2-20. The average temperature for a region varies with both latitude and altitude, as shown in Figure 2-21. Microclimate and Other Abiotic Factors A specific site may have temperature and moisture conditions that are significantly different from the overall, or average, climate of the region in which it is located. For example, a south-facing slope, which receives more direct sunlight in the northern hemisphere, will be relatively warmer and hence also drier than a north-facing slope. Similarly, the temperature range in a sheltered ravine will be narrower than that in a more exposed location, and so on. The conditions found in a specific localized area are referred to as the microclimate of that location. In the same way that different climates determine the major biome of a region, different microclimates result in variations of ecosystems within a biome. Soil type and topography may also contribute to the diversity found in a biome, because these two factors affect the availability of moisture. In the eastern United States, for example, oaks and hickories generally predominate on rocky, sandy soils and on hilltops, which retain little moisture, whereas beeches and maples are found on richer soils, which hold more moisture, and red maples and cedars inhabit low, swampy areas. In the transitional region between desert and grassland [10-20 inches (25- 50 cm) of rainfall per year], a soil capable of holding water will support grass, but a sandy soil with little ability hold water will support only desert species. In certain cases, an abiotic factor other than rainfall or temperature may be the primary limiting factor. For example, the strip of land adjacent to a coast frequently receives a salty spray from the ocean, a factor that relatively few plants can tolerate. Consequently, an association of salt-tolerant plants frequently occupies this strip, as on a barrier island. Relative acidity or alkalinity (pH) may also have an overriding effect on a plant or animal community. Biotic Factors

Some biotic factors - that is, factors caused by other species-may be limiting. Grasses thrive when rainfall is more than 30 inches (75 cm). When the rainfall is great enough to support trees, however, increased shade may limit grasses. Thus, the factor that limits grasses from taking over high-rainfall regions is biotic - namely, the overwhelming competition from taller species. The distribution of plants may also be limited by the presence of certain herbivores; elephants, for example, are notorious for destroying woodlands, so their presence leads predominantly to grasslands. Limiting factors also apply to animals. As with plants, the limiting factor may be abiotic - cold temperatures or lack of open water, for instance- but it is more frequently biotic, such as the absence of .a plant community that would otherwise provide suitable food or habitat. The nutrient cycles of the tropical rainforest are unique. Almost (90%) of the nutrients in the system are contained in the bodies of living organisms. This is a strinking contrast to temperate deciduous forest, where nutrients are held within the soil and made available for new plant growth. The luxuriant growth in tropical rainforests depends of rapid decomposition and recycling of dead organic material. Leaves and branches that fall to the forest floor decay and are incorporated almost immediately back into living biomass. When the forest is removed for logging, agriculture, and mineral extraction, the thin soil cannot support continued cropping and cannot resist erosion from the abundant rains. And if the cleared area is too extensive, it cannot be repopulated by the rainforest community. Rapid deforestation is occurring in many tropical areas as people move into the forests to establish farms and ranches, but the land soon loses its fertility. Physical Barriers A final factor that may limit species to a particular region is the existence of a physical barrier, such as an ocean, a desert, or a mountain range, that species are unable to cross. Thus, species making up the communities on separate continents or remote islands are usually quite different, despite living in similar climates. When physical barriers are overcome - as when humans knowingly or unknowingly transport a species from one continent to another - the introduced species may make a successful invasion. The starling, for example, originally confined to Eurasia, has successfully invaded North America. Note also that humans erect barriers-dams, roadways, aboveground pipelines, cities, and farms-that may block the normal movement of populations and cause their demise. For example, the Atlantic salmon is now an endangered species in some New England states because of the many dams that prevent the migration they require for spawning. Summary The biosphere consists of a great variety of environments, both aquatic and terrestrial. In each environment, plant, animal, and microbial species are adapted to all the abiotic factors. In addition, they are adapted to each other, in various feeding and nonfeeding relationships. Each environment supports a more or less unique grouping of organisms interacting with each other and with the environment in a way that perpetuates or sustains the entire group. That is, each environment, together with the species it supports, is an ecosystem. Every ecosystem is tied to others through species that migrate from one system to another and through exchanges of air, water, and minerals common to the whole planet. At the same time, each species-and, as a result, each ecosystem-is kept within certain bounds by limiting factors. The spread of each species is limited at some point because that species is unable to tolerate particular conditions,

to compete with other species, or to cross some physical barrier. The distribution of species is always due to one or more limiting factors. BIOMES These are the natural broad biotic zones of the biosphere called, Biomes. Each biome is characterized by uniform life form of vegetation such as grass, desert plants, deciduous trees or coniferous trees. A Biome is a large ecosystem which is embracing the large landscape, characterised by specific flora and fauna. Biomes can be classified as : A. Terrestrial : These are the biomes found on land e.g„ Tundra, forest, deserts, grasslands B. Aquatic. These are the biomes found in water. These can be : (i) Fresh waters, such as pond, lake and river (ii) Marine as oceans, shallow sea Terrestrial Biomes A. Forests : Forests are one of the largest plant formations, densely packed with tall and big trees. Forests are of many different types, depending on the climatic regime in which they are found. Three main forest types are: 1. Tropical rain forests 2. Temperate deciduous forests 3. Boreal or north coniferous forests (Taiga) 1. Tropical Rain (Ever green) Forest : These are in the tropical region showing very high rain fall. These forests occur between tropics of cancer and capricorn. Such forests are well developed over the western coast of India and North eastern Himalayas and scattered in south east Asia, west Africa and north coast of South America. Main characteristics

• Temperature and light intensity are very high • Rain fall is greater than 200 cm. per year. • Soil of these regions is rich in humus, • The rate of turn over of the nutrients is very high leading to high productivity and have

highest standing crop and biomass The vegetation includes brood evergreen trees of about 200 feet like bamboos, ferns, shrub etc. Epiphytes and woody wines (liannas) are also abundant. Many tree species show buttresses (swollen stem bases) and leaves with drip tips. These forests have rich invertebrate and vertebrate fauna. Snails, centipedes, millipedes and many insect species are common near the forest floor. Rhacophorus (lying frog), aquatic reptiles, Chameleon and many birds are common in these forests. Mammals of these forests are sloths , monkeys, ant eaters, leopards, jungle cats and giant flying squirrels. 2. Temperate Deciduous Forests : Trees of deciduous forests shed their leaves in autumn and a new foliage grows in spring. They occur mostly in northwest, central and eastern Europe, eastern north America, north China, Korea, Japan, far eastern Russia and Australia. Climate : These forests occur in the areas of moderate climatic conditions such as

• Annual rainfall is 75 to 150 cm • Winter lasts for four to six months. • Temperature ranges between 10 to 20°C. • Soil is brown and rich in nutrients.

Flora and fauna : Commonly found trees in this ecosystem are oak, birch heath, hickory, bass wood, chest nuts, pitch pine, cypress. Invertebrate fauna comprises green oak moth, bark beetle, green flies, aphids, sapflies, moths and butterflies. Prominent grazers are grass eating

rodents, deer and bison. Rodents play a very important role in these forests. They feed on the seeds, fruits and leaves of the trees and consume much more food than the large sized grazers. Common carnivores in temperate forests are wild cat, wolves, foxes, tawny owl and sparrow hawk. Black bear, raccoons and skunks are the omnivorous animals of these forests. 3. Coniferous forests : Coniferous forests are also known as Taiga or Boreal forests. They extend as a continuous belt across north America and north Eurasia below the arctic tundra. In the Himalayas, these are distributed above 1700 to 3000 metre altitude. They also occur at high altitude below the alpine tundra and tree line. Climate : Climate is cold.

• Long and harsh Winters is for more than six months. Mean annual temperature is below 0°C,

• Soil is poor in nutrients and acidic in nature. Flora and fauna : Coniferous forests are characterized by conifers (gymnosperms). They are evergreen, drought resistant and woody. In many species the canopy is cone shaped. The common species of trees of these forests are Spruce, fir and pine trees. The productivity is much less than other ecosystem. There are very few animals in these forests. The herbivores are red squirrel, deer, goat, mule, moose etc. The carnivores are timber wolves, lynxes, wolverine, weasels mink and bear. Some common birds are cross bill, thrushes, warblers, flycatchers, robin and sparrow. B. Grasslands Distribution : Grasslands are dominated by the grasses. They occupy about 20% of the land on earth’s surface. They occur in both tropical and temperate regions where environmental conditions are better than that of the desert but rainfall is not enough to support the growth of trees. Grasslands represent an ecotone (a zone in between two ecosystems) and are found between forest on one side and deserts on the other. They are subjected to greater variation of temperature, moisture, wind and light intensity of the sun.. Grasslands are known by various names in different parts of the world. For example they are called prairies, steppes, savannas and pampas. Tropical grasslands are commonly called Savannas. They occur in eastern Africa South America, Australia and India. Savannas form a complex ecosystem as they contain grasses with groups of trees. Soil of grassland is rich and fertile. Flora and fauna : Grasses are the dominating plants with scattered drought resistant trees in the tropical grasslands. The height of grasses ranges from 0.2 to 3 meters depending upon the annual rain fall Trees are less than 10 m in height. Animals are very much reduced in grasslands because there is no shelter. The large herbivores of this biome are bison, proghorn (North America) wild horse, ass, saiga (Eurasia) , zebra and antelope (South Africa). Carnivores are quite small in number and size They are coyotes, weasels, badgers foxes and ferrets . Hawks, lark sparrows, warblers, Great Indian Bustard and peafowl are the common birds found in grassland. Grasslands are very rich in reptilian and insect fauna. C. Deserts Distribution : Deserts are waterless barren regions of the earth. They occupy about one-seventh of the land on earth’s surface. Deserts form an extreme condition in sequence of ecosystems with respect to the climatic condition . They occur in two belts that encircle the northern and southern hemispheres roughly centered over the tropics of Cancer and Capricorn. Sahara deserts of Africa are the largest. Indian Thar deserts are an extensions of Sahara deserts through Arabian and Persian deserts. Climate:

• Annual rain fall is very little. It may be less than 25 cm per annum. At some places if it is high it is unevenly distributed.

• Temperature may be very high in subtropical deserts and very low in cold deserts e.g. Ladakh.

• Winds have high velocity. Flora and fauna : Cacti, Acacia, Euphorbia and prickly pears are some of the common desert plants. Desert animals are insects, reptiles, and burrowing rodents. Desert shrew, fox, kangaroo, wood rat, rabbit, armadillo are common mammals in desert. Camel is known as the ship of the desert as it can travel long distances without drinking water for several days. D. Tundra The word tundra means a “barren land” since they are found in those regions of the world where environmental conditions are very severe. There are two types of tundra arctic and alpine. Distribution

• Arctic tundra extend as a continuous belt below the polar ice cap and above the tree line on the northern hemisphere. It occupies the northern fringe of Canada Alaska, European Russia, Siberia and island group of arctic ocean.

• Alpine tuundra occur at high mountain peaks above the tree line. Since mountains are found at all latitudes therefore alpine tundra show day and night temperature variations

Climate • A permanently frozen subsoil called permafrost is found in the arctic and antarctic

tundra. The summer temperature may be around 15°C a nd in winter it may be as low as –57°C in arctic tundra A very low precipitation of less than 400 mm per year

• A short vegetation period of generally less than 50 days between spring and autumn frost

• Productivity is low Flora and fauna : Typical vegetation of arctic tundra is cotton grass, sedges, dwarf heath, willows birches,and lichens. Animals of tundra are hurepian reindeer, musk ox, arctic hare, caribous, lemmings and squirrel. Their body is covered with fur for insulation, Insects have short life cycles which are completed during favourable period of the year. AQUATIC BIOMES Oceans, lakes, wetlands, and other aquatic ecosystems cover more than two-thirds of the earth's surface and play a vital role in biological productivity, biogeochemical cycles, climate modification, and species diversity. Freshwater and Saline Ecosystems Freshwater ecosystems include rivers and streams as well as ponds, lakes, and wetlands containing water with relatively low salt concentrations. There are also some unique freshwater ecosystems that we rarely see, such as underground rivers and subterranean pools. Saltwater ecosystems cover vastly more total area and contain much greater volume of water than all freshwater bodies combined. The oceans comprise the bulk of all water in the world. In addition, some lakes such as the Great Salt Lake in Utah or the Dead Sea in Israel, as well as inland seas such as the Caspian, also contain saline (salty) water. Smaller salty and mineral-rich ponds and small lakes are fed by mineral hot springs or formed by evaporation in enclosed basins, especially in desert regions. Aquatic ecosystems are as varied as their individual sites because they are influenced not only by characteristics of local climate, soil, and resident communities but also by the adjacent terrestrial ecosystems and anything that happens uphill or upstream from them. As with

terrestrial ecosystems, the biological communities of aquatic ecosystems are largely determined by the physical characteristics of the environment, except that the surrounding medium is water instead of air. Aquatic organisms have the same basic needs as terrestrial organisms: carbon dioxide, water, and sunlight for photosynthesis; oxygen for respiration; and food and mineral nutrients for energy, growth, and maintenance. The availability of these necessities is influenced by such site characteristics as (1) substances that are dissolved in the water, such as oxygen, nitrates, phosphates, potassium compounds, and other by-products of agriculture and industry; (2) suspended matter, such as silt and microscopic algae, that affect water clarity and, therefore, light penetration; (3) depth; (4) temperature; (5) rate of flow; (6) bottom characteristics (muddy, sandy, rocky); (7) internal convective currents; and (8) connection to, or isolation from, other aquatic ecosystems. Vertical stratification is an important aspect of many aquatic ecosystems, especially in regard to gradients of light, temperature, nutrients, and oxygen. Organisms tend to form distinctive vertical subcommunities in response to this stratification of physical factors. The plankton subcommunity consists mainly of microscopic plants, animals, and protists (single-celled organisms such as amoebae) that float freely within the water column. Some nonplanktonic organisms are specialized to live at the air-water interface (for example, insects such as water striders), and still others are able to swim freely in the open waters (such as fish). Finally, many animal species are bottom dwellers (such as snails, burrowing worms and insect larvae, bacteria) that make up the benthos, or bottom subcommunity. Oxygen levels are lowest in the benthic environment. Anaerobic bacteria can live in the very low-oxygen bottom sediments. Emergent plants such as cattails and rushes are rooted in bottom sediments of the littoral (near shore) zone but spread their leaves above the water surface. They create important structural and functional links between strata of the ecosystem and often are the greatest producers of net primary productivity in the ecosystem. Deeper water bodies are characterized by the presence of a warmer, upper layer that is mixed by the wind (the epilimnion; epi = upon) and a colder, deep layer that is not mixed (the hypolimnion; hypo = below) (fig. 5.13). The two layers are separated by a distinctive temperature transition zone called the thermocline, or mesolimnion. Smaller lakes, ponds, and nearshore zones have a tendency to undergo succession, which includes changes in the biological community as a response to increases in nutrient levels. Human sources of nutrient input can radically increase the rate at which a water body "ages," known as “eutrophication”. Estuaries and Wetlands: Transitional Communities Estuaries are bays or semi-enclosed bodies of brackish (salty but less so than seawater) water that form where rivers enter the ocean. Estuaries usually contain rich sediments carried downriver, forming shoals and mudflats that nurture a multitude of aquatic life. Estuaries are sheltered from the most drastic ocean action but do experience tidal ebbs and flows. Daily tides may even cause river levels to rise and fall far inland from the river mouth. The combination of physical factors in estuaries makes them very productive and of high species diversity. They are significant "nurseries" for economically important fish, crustaceans (such as crabs and shrimp), and mollusks (such as clams, cockles, and oysters).

Where the continental shelf is broad and shallow, an extensive fan-shaped sediment deposit called a delta may form at the river mouth. Deltas often are channeled by branches of the river, creating extensive coastal wetlands that are part of the larger estuarine zone. Wetlands of several types form near bodies of water. Wetlands are ecosystems in which the land surface is saturated or covered with standing water at least part of the year and vegetation is adapted for growth under saturated conditions. There are special names for specific kinds of wetlands, but we can group them into three major categories: swamps, marshes, and bogs and fens. Defined pragmatically, swamps are wetlands with trees; marshes are wetlands without trees; and bogs and fens are areas that may or may not have trees, and have waterlogged soils that tend to accumulate peat. Swamps and marshes tend to be associated with flowing water. Fens are fed by groundwater and surface runoff, whereas bogs are fed solely by precipitation. Swamps and marshes generally have high productivity, while bogs and fens have low productivity. The water in marshes and swamps usually is shallow enough to allow full penetration of sunlight and seasonal warming. These mild conditions favor great photosynthetic activity, resulting in high productivity at all trophic levels. In short, life is abundant and varied. Wetlands are major breeding, nesting, and migration staging areas for waterfowl and shorebirds. Wetlands perform major ecosystem services, the importance of which cannot be overstated. As mentioned previously, they support a great diversity of life-forms. What may be less obvious is their role in planetary water relationships. Wetlands act as traps and filters for water that moves through them. Runoff water is slowed as it passes through the shallow, plant-filled areas, reducing flooding. As a result, sediments are deposited in the wetlands instead of traveling into rivers and, eventually, the oceans. In this way, wetlands both clarify surface waters and aid in the accumulation and formation of fertile land. Furthermore, chemical interactions in wetland ecosystems neutralize and detoxify substances in the water. Finally, water in wetlands seeps into the ground, helping to replenish underground water reservoirs called aquifers. Wetlands convert naturally to terrestrial communities largely through sedimentation, eutrophication, etc. Human activities greatly accelerated these processes in many places, and wetlands are being destroyed or degraded around the world at a disturbing rate. This destruction is of great concern because it means loss of ecological services to the biosphere as well as loss of essential habitats for a myriad of species. Coral Reefs Coral reefs form in clear, warm, tropical seas and are particularly well developed in the south Pacific. They are the accumulated calcareous skeletons of innumerable tiny colonial animals called corals. Each of the interconnected coral animals builds a calcium carbonate chamber on the surface of the accumulated secretions of previous generations of animals. Coral reefs usually form along the edges of shallow, submerged banks or shelves. The depth at which they form is limited by the depth of light penetration, due at least in part to the presence of symbiotic photosynthetic protists in their tissues. Because of the photosynthetic relationship, the presence of dead versus living coral growths can be an index of either previous ocean levels or decreased light penetration due to increased turbidity. Coral reef communities rival tropical forest communities in species diversity, numbers of individuals, brilliance of color, and interesting forms of both plants and animals.

Reefs also are among the most endangered biological communities on the earth. Destructive fishing practices (using dynamite or cyanide to stun fish, for instance) and harvesting of coral for building or the pet trade have damaged or destroyed about three-fourths of all reefs in the world. In the next section, we will discuss some other types of human disturbance of natural habitats. HUMAN DlSTURBANCE Humans have become dominant organisms over most of the earth, damaging or disturbing more than half of the world's terrestrial ecosystems to some extent. By some estimates, humans preempt about 40 percent of the net terrestrial primary productivity of the biosphere either by consuming it directly, by interfering with its production or use, or by altering the species composition or physical processes of human-dominated ecosystems. Conversion of natural habitat to human uses is the largest single cause of biodiversity losses. Researchers have attempted to map the extent of human disturbance of the natural world. The greatest impacts have been in Europe, parts of Asia, North and Central America, and islands such as Madagascar, New Zealand, Java, Sumatra, and those in the Caribbean. Temperate broad-leaved forests are the most completely human-dominated of any major biome. The climate and soils that support such forests are especially congenial for human occupation. In eastern North America or most of Europe, for example, only remnants of the original forest still persist. Regions with a Mediterranean climate generally are highly desired for human habitation. Because these landscapes also have high levels of biodiversity, conflicts between human preferences and biological values frequently occur. Temperate grasslands, temperate rainforests, tropical dry forests, and many islands also have been highly disturbed by human activities. Former prairies have been converted to farmlands in many countries. Intensive cultivation of this land exposes the soil to erosion and fertility losses. Islands, because of their isolation, often have high numbers of endemic species. Many islands, such as Madagascar, Haiti, and Java have lost more than 99 percent of their original land cover. Tundra and Arctic deserts are the least disturbed biomes in the world. Harsh climates and unproductive soils make these areas unattractive places to live for most people. Temperate conifer forests also generally are lightly populated and large areas remain in a relatively natural state. However, recent expansion of forest harvesting in Canada and Siberia may threaten the integrity of this biome. Large expanses of tropical moist forests still remain in the Amazon and Congo basins but in other areas of the tropics such as West Africa, Madagascar, Southeast Asia, and the Indo-Malaysian peninsula and archipelago, these forests are disappearing at a rapid rate. As mentioned earlier, wetlands have suffered severe losses in many parts of the world. About half of all original wetlands in the United States have been drained, filled, polluted, or otherwise degraded over the past 250 years. Similar wetland disturbances have occurred in other countries as well. In New Zealand, over 90 percent of natural wetlands have been destroyed since European settlement. In Portugal, some 70 percent of freshwater wetlands and 60 percent of estuarine habitats have been converted to agriculture and industrial areas. In Indonesia, almost all the mangrove swamps that once lined the coasts of Java have been destroyed, while in the Philippines and Thailand. more than two-thirds of coastal mangroves have been cut down for firewood or conversion to shrimp and fish ponds.