ENDANGERED ECOSYSTEMS

Raymond C. Nias and John R. Mooney WWF Australia

I. Introduction to some degree adversely affected by human activities, II. Major Ecosystems at Risk with forests, scrub and grasslands, and freshwater and III. The Conservation of Ecosystems coastal ecosystems being the most threatened. Specific ecosystems at high risk include dry tropical forests, especially on islands, temperate forests, Mediterranean shrublands, temperate grasslands, and most coastal GLOSSARY marine systems. Overall, the large marine and oceanic ecosystems, polar regions, and dry deserts are gene- biological diversity The variety of genes, species, rally less threatened, although the potential impacts of and ecosystems in the living world. climate change on these ecosystems are only just biome Group of ecosystems with similar character- beginning to be understood. istics, usually a major vegetation type such as trop- ical rain forest or grassland. community All of the populations of different organ- I. INTRODUCTION isms that live within a given area. conservation status Relative likelihood of extinction A. Definition of an Endangered Ecosystem of a species or community. deforestation Physical removal of trees and conse- The Convention on Biological Diversity (CBD) 1992, quent reduction in forest cover. defines an ecosystem as ‘‘a dynamic complex of plant, ecoregion Geographic region of similar ecological animal and micro-organism communities and their non- processes and ecosystems. living environment interacting as a functional unit.’’ By ecosystem A dynamic complex of plant, animal, and itself, however, the term ‘‘ecosystem’’ does not define any microorganism communities and their nonliving specific dimensions and the boundaries of ecosystems environment interacting as a functional unit. are often indistinct. Even in aquatic ecosystems, where endangered Very likely to become extinct within the the presence of water helps to identify the boundaries of near future. lakes and rivers, the extent of an aquatic ecosystem endemism Degree to which species are unique to a fluctuates with changing water levels, floods, and tides. specific location. In the marine environment, ecosystems may be defined by particular attributes of water temperature or chem- istry, or by the characteristics of the substrate, in addi- tion to specific plant communities, such as sea grass THE SCALE OF HUMAN IMPACT on the natural beds or kelp forests. Other ecosystems may be defined environment has resulted in the decline and loss of by specific geographic or special physical characteristics, many ecosystems. All of the world’s major biomes are such as caves or seamounts.

Encyclopedia of Biodiversity Copyright & 2007 Elsevier Inc. All rights of reproduction in any form reserved. 1 2 ______ENDANGERED ECOSYSTEMS______

The concept of an endangered ecosystem is The purpose of the Millennium Ecosystem Assess- relatively new as compared with the widely accepted ment (MA) as stated in the foreword to the Biodiversity concept of an endangered species. The World Cons- Synthesis report was to ‘‘assess the consequences of ervation Union (IUCN) has maintained an inter- ecosystem change for human well-being and to estab- nationally recognized system of Red Data Books lish the scientific basis for actions needed to enhance for defining and listing threatened species for many the conservation and sustainable use of ecosystems and years, but no universally applied system has been their contributions to human well-being.’’ The report developed for ecosystems so far. Similarly, there is no includes global overviews of major ecosystem types recognized system for measuring the relative cons- including marine systems, coastal systems, inland wa- ervation status of an ecosystem and it is often not clear ter systems, forest systems, dryland systems, island in what sense the whole of the ecosystem can be seen systems, mountain systems, and polar systems. In ad- to be threatened. While it is clear in most cases at what dition to these overviews, 18 subglobal assessments point a species has become extinct, it is much less were commissioned as part of the overall project. clear at what point a specific ecosystem ceases to exist. The conclusions of the MA are graphic in their The uncertainty in defining the exact extent of an portrayal of ecosystem loss and state that ‘‘virtually all ecosystem has hampered attempts to quantify their of Earth’s ecosystems have now been dramatically conservation status, and there is an ongoing debate as transformed through human actions.’’ In summary, to the appropriate scale for organizing and prioritizing over half of the 14 biomes that the MA assessed have conservation efforts. At the broadest level, ecosystems experienced a 20–50% conversion to human use, with cross international boundaries and are subject to a temperate and Mediterranean forests and temperate wide range of threats and human influences. These grasslands being the most affected. major ecosystem types can be subdivided, as they vary At the national level, both the United States and enormously in their biological composition, environ- Australia have undertaken recent reviews of threat- ment, and functioning, often as a result of major ened ecosystems. In Australia, some 2859 threatened geographic features such as mountain ranges, bays, ecosystems were identified in 2002, the majority of and river catchments. At a finer level, an ecosystem these being ecosystems associated with eucalypt forest may comprise a small group of underwater cave sys- and woodlands. tems, sand dunes, an isolated island and fringing coral reef, or a mossy high-altitude swamp that covers no more than a few hectares. II. MAJOR ECOSYSTEMS AT RISK A. Forests and Woodlands B. Global Reviews of Endangered Ecosystems The net reduction in global forest and woodland cover The paucity of information on many ecosystems, as is estimated to be 5.3 million ha/yr, with more than well as the lack of a standard approach, has hampered one-third converted globally since 1700, mostly as a past attempts at national or global assessments of result of expanding human populations and agricul- conservation status. However, recent progress in de- ture. Trends in deforestation and net changes in forest termining the conservation status of ecosystems at a area vary across regions, although there are many global level has been made in response to the iden- commonalities within major biomes across regions. In tified need for an international ecosystem assessment densely populated subregions, such as western Europe by a number of international agencies. Organizations and southern China, this level of conversion has been that have been involved in global reviews of threatened much greater, with o30% of original vegetation cover ecosystems include the United Nations Environment now remaining. Programme, and nongovernmental organizations such The large-scale loss of ecosystems resulting from as Conservation International (biodiversity hotspots) human influence has been most apparent in the and WWF (Global 200 ecoregions). The most signi- conversion of fertile temperate forests into cropland ficant of these have been published by the United Na- and pasture. Considerable decline in forest area had tions Environment Programme in the form of the already taken place by 1700, especially in the Medi- Global Environment Outlook series and The World terranean Basin and the Indus Valley and in northern Resource Institute’s Millennium Ecosystem Assessment and northwestern China. Large declines also occurred (Reid et al., 2005). in northwestern Europe during the Middle Ages. ______ENDANGERED ECOSYSTEMS______3

Primary or old growth forest (more than 200 years old) limited, but settlement and agriculture around roads is now only a small part of the world’s total forest area. built to transport timber have resulted in additional In contrast to the Mediterranean region, developm- clearing of forest areas. ent in North America did not lead to the almost com- In South America, deforestation is also mainly due plete loss of forest. Over some 150 years, an initial to the expansion of agriculture. This process is driven rapid conversion of forested land was followed by a by a number of factors, the most important being the slowing down in clearance rates, and eventually by displacement of peasant farmers from traditional far- stabilization. In Australia, some 47% of all forests were ming areas, large-scale settlement programs such as in cleared over the last 200 years, mostly during the pe- Rondoˆnia in Brazil, and the deliberate promotion of riod of rapid economic expansion and mechanized livestock-raising activities in the Amazon through fi- clearing of native woodlands for agriculture in the nancial incentives. In addition, commercial logging, mid-twentieth century. collection of firewood for household use, and road The major areas of rapid deforestation currently are construction have all led to the unsustainable exploi- in the tropics. Africa accounts for over 50% of recent tation of the region’s forests. Deforestation has been net global deforestation, although the continent hosts most severe on the Pacific coast of Central America, only 17% of the world’s forests. Ten tropical countries where o2% of the original 550,000 km2 remains, and (six of them in Africa) had net annual change in forest within the Atlantic forests of Brazil, which is left with areas of more than 3%, and four countries (three in only 4% of its original 1 million km2 as pristine forests. Africa plus Nicaragua) had change rates of 2.5–3.0% The rapid loss of highly diverse native forests is of between 1990 and 2000. particular concern, because they are often replaced by A similar pattern of forest loss is now occurring in the species-poor pastures or by monocultures of exotic developing (mostly tropical) world. These patterns are timber species. Most of the endangered tropical plants again fueled by expanding human populations and agri- in Brazil (65%) are found in this highly endangered culture, with the added impetus of industrial crops such tropical forest ecosystem. as rubber and oil palm. It is clear that deforestation, In the Asia and Pacific region deforestation has in- particularly in the tropics, is having extremely negative creased from 2 million ha/yr during 1976–1981 to 3.9 impacts on forested ecosystems. Fifteen of the world’s 25 million ha/yr in 1981–1990, with Bangladesh, Pakistan, biodiversity ‘‘hotspots’’ originally identified by Norman the Philippines, and Thailand experiencing the fastest Myers in 1997 contain tropical forests (Myers, 1997). rate of forest clearance. The Pacific subregion has the These areas once covered nearly 12% of Earth’s land lowest rate of deforestation (around 130,000 ha/yr), surface, but their remaining natural habitat has now most of which occurs in Papua New Guinea. Rapid been reduced to only 1.4% of that surface. population growth has contributed to depletion of for- ests not only through land clearing for cultivation but 1. Clearing in Tropical Forests also through overharvesting of forests for fuelwood, All of the world’s major tropical forest ecosystems are roundwood, and fodder. At the current rate of harves- being rapidly cleared, the only exception at this point ting, the remaining timber reserves in Asia may not last being the relatively intact forests of the island of New for more than 40 years. Guinea. The remaining forests in humid West Africa, Although the extent of forest cover in Europe may for example, are disappearing at the rate of about 2% a be significant and stable, or even increasing in parts, year, and exceeding 5% in the extreme case of Coˆte many of the elements of the forest ecosystem have d’Ivoire. The relic blocks of forests left at Gola in Sierra been severely modified or lost and for this reason are Leone, at Sapo in Liberia, and at Tai in Coˆte d’Ivoire considered to be threatened. Mature natural forest eco- are now of global importance as the last significant systems are very rare. In northern and Central Europe remains of the structurally complex and species-rich this rarity has been caused primarily by intensive forests of the upper Guinea zone. Some areas, such as logging, resulting in a significant decrease in the Fouta Djallon, Mount Nimba, and Loma at the head of integrity and natural condition of forests. Forests have major watersheds in western Africa (the Niger, been modified significantly to increase their commer- Senegal, and Gambia Rivers), harbor exceptional cial value at the expense of natural ecosystem com- biodiversity. The major cause of deforestation is clear- plexity and structure. They are more likely to contain ance for agriculture (particularly commercial farming uniform, relatively even-aged stands, with little dead and to some extent shifting cultivation) and the timber, and with a significantly reduced complement harvesting of fuelwood. Commercial logging is of animal species. In addition, there has been extensive 4 ______ENDANGERED ECOSYSTEMS______use of nonnative species such as Sitka spruce (Picea 165 Ma, Madagascar drifted away from Africa, which sitchensis) in the north and eucalyptus (Eucalyptus allowed its native species to evolve in isolation from spp.) in the south. the mainland continent. Among the many unique spe- Only the United States and Western European cies are the lemurs—members of the primate family countries currently harvest less wood from available found only in Madagascar and the neighboring Co- forest land than they regrow annually. Canada, Russia, moros Islands—including the recently discovered Central and eastern Europe, and most developing mouse lemur (Microcebes myoxinus) and golden- countries harvest above replacement rates in their crowned sifaka (Propithecus tattersalli), both of which available forest areas. appear to be restricted to this ecosystem. Table I shows examples of some of the most end- angered and biologically diverse forest ecoregions in 4. Temperate Forests of the Caucasus the world. It is clear from this table that many tropical Temperate forests have also been extensively cleared moist forests are endangered, particularly forests in for hundreds of years and few large examples remain western Africa, the lowland forests of Southeast Asia, intact. Forest loss has been most severe in western Eu- and forests on islands such as Madagascar and the rope, and most examples of this forest type are now Philippines. Twenty-nine of a total of 53 tropical and restricted to Central and eastern Europe. The Caucasus subtropical moist forest ecoregions are endangered. ecoregion harbors some of the most diverse and dis- Although rapid development of these regions for agri- tinctive temperate conifer and broad-leaved forests in culture and large-scale commercial logging have been Eurasia, as well as rich woodlands, steppe, and grass- primarily responsible for this extensive forest loss, lands. One of the world’s seven temperate rain forests large-scale fire now poses a major problem in some of formerly occurred here, but this habitat has been virtu- the previously contiguous forests of Indonesia and Ma- ally destroyed. Lowland forests are dominated by oak, laysia, especially during periods of prolonged drought. chestnut, and lime, while higher regions are covered by beech, fir, and spruce. Although the ecoregion covers a 2. Mediterranean Forests relatively small area, its varied range of landscapes and The Mediterranean forests have lost much of their climates, and its geographic position at the edge of natural condition as a result of excessive logging, fire, Europe and Asia, which represent many of their re- and overgrazing by livestock, especially goats. Forests spective species, has given the ecoregion a high level of are especially threatened at the boundaries of their biological diversity. In the Caucasus Mountains alone, natural distribution, such as the forest–steppe regions more than 6400 species of vascular plants have been of southern Ukraine and Russia or in the Mediterra- recorded (of which 23% are endemic), as well as 7000 nean Basin. Most of the Central Europe’s alluvial for- species of ferns, lichens, and mosses. ests along all major river courses have virtually disappeared. Airborne pollution (mostly in the form 5. Temperate Forests of China of acid deposition and photochemical smog) is also a The temperate forests of southern China are among major cause of damage to forest ecosystems in Europe, the world’s most biodiverse and endangered temperate particularly in Central and eastern Europe. First re- forest ecosystems. Subtropical evergreen broad-leaved ported in the Black and Bavarian forests of Germany in forest is the dominant vegetation of this ecoregion, the early 1970s, damage from air pollution may now which also includes alpine ecosystems, steppe grass- be detected in a quarter of all European trees. lands, and wetlands. Alpine vegetation of the Qiin- ghai–Tibet plateau predominates in the west and the 3. Dry Tropical Forests higher regions in the southwest of the Hengduan Similar problems face the seasonally dry forests, espe- Mountains. Deciduous broad-leaved forests of the cially the monsoonal forests and conifer forests in the warm temperate zone occur north of the province. tropical and subtropical regions of the world, because Though the biological richness of China and Sichuan these are often more restricted in their original distri- is well recognized, international attention has largely bution. The biologically rich dry forests of Madagascar focused on a single species that has become a symbol and Central and South America are now much re- for conservation efforts worldwide—the giant panda duced. The remaining dry forests of Madagascar rep- (Ailuropoda melanoleuca). Sichuan province is home to resent some of the richest dry forest ecosystems in the the vast majority of the world’s wild pandas. Loss of world in terms of their natural diversity. Around vegetation cover is one of the main threats to wildlife ______ENDANGERED ECOSYSTEMS______5

TABLE I Some endangered forest ecosystems

Region Tropical and subtropical Tropical and subtropical dry and Conifer and temperate moist broad-leaved forests monsoon broad-leaved forests broad-leaved forests

Africa Madagascar moist forests Madagascar dry forests Guinean moist forests (West Africa) Maputaland–Pondoland dry Eastern Arc montane forests forests East African coastal forests Albertine Rift highland forests (central Africa) Seychelles and Mascarene Islands forests Gulf of Guinea island forests Macronesian (Atlantic islands) forests Congolian coastal forests (West Africa) Asia Western Ghats moist forests (India) Western Himalayan Sri Lankan moist forests temperate forests Peninsular Malaysia lowland and Central China temperate montane forests forests Sumatran–Nicobar Islands forests Eastern Himalayan broad- Northern Borneo–Palawan moist forests leaved and conifer forests Philippines moist forests Southeast China subtropical forests Hainan Island forests (China) Nansei Shoto Archipelago forests ( Japan) Australasia and Pacific New Caledonia moist forests New Caledonia dry forests New Zealand subtropical forests Hawaiian dry forests Lord Howe and Norfolk Island forests (Australia) Hawaiian moist forests South Pacific island forests Europe and Russia Southern European montane forests Latin America and Brazilian Atlantic forests Bolivian lowland dry forests Mexican pine–oak forests Caribbean Northern Andean montane forests Tumbesian and North Inter- Greater Antilles pine forests Coastal Venezuela montane forests Andean Valleys dry forests Valdivian temperate rain Greater Antilles moist forests Southern Mexican dry forests forests (Chile) Varzea flooded forests North America Klamath–Siskiyou coniferous forests Appalachian and mixed mesophytic forests Pacific temperate rain forests (United States and Canada) Sierra Nevada conifer forests Southeastern conifer and broad-leaved forests in the province and half of the panda’s habitat B. Scrub, Heath, and Grassland Ecosystems (10,000 km2) was lost between 1974 and 1989 alone. Logging and small-scale agriculture are the main rea- Despite their often uniform appearance, low-stature sons for this decline. Hunting in wildlife reserves and vegetation communities of the type referred to as human disturbance from people collecting medicinal scrubs, heaths, and grasslands are complex and varied, plants are additional concerns. with many regional variations and subtle differences 6 ______ENDANGERED ECOSYSTEMS______resulting from soil type and climate. They are usually continent and supported huge herds of grazing ani- present where soil nutrients, water availability, or cli- mals such as the bison. Originally thought to be poor mate are not conducive to the growth of forests. They agricultural lands, because of the scarcity of trees, the are well suited, however, to grazing by domestic prairie ecosystem was discovered to be immensely fer- animals and for conversion to cultivation, especially tile, and during the period from the early 1800s to cereal crops. As a result of their suitability for agri- 1930, about 90% of this ecosystem was converted to cultural development, temperate scrubs, heaths, and farmland. grasslands are among the most modified of the world’s Closer to the tropics, large areas of tropical savan- major ecosystems. nas and grasslands can still be found in Africa, Aus- Large areas of current and former temperate scrub tralia, and South America. Most of these savannas are and grasslands occur throughout continental Europe used for pastoralism, and the impact of large numbers and Asia and North America. In northern polar regions, of grazing animals, often poor soils, changed fire these communities extend into the Arctic Circle, for- regimes, and human settlements have modified and ming a vast patchwork of semifrozen and permanently degraded many areas. As native vegetation cover de- frozen swamps and low vegetation. This latter region clines, soil erosion proceeds and turns these semiarid appears to be relatively intact, although the future im- ecosystems into deserts. pacts of global warming might considerably alter the Table II shows some of the most endangered and distribution and extent of these ecosystems. biologically diverse ecoregions of this type in the European communities of this type range from the world. Many temperate ecosystems have been lost, or Arctic tundra to the Mediterranean shrublands, inclu- so extensively modified that it is difficult to determine ding many different types of woody shrub communi- their original nature. In Australia, for example, o1% ties (including maquis and dwarf shrub heath), tall of the original temperate lowland grasslands remain, herb stands, and many types of grassland. They occur much of this restricted to roadsides, railway lines, at all altitudes and can range from very sparse to very cemeteries, and lightly grazed unimproved pastures. dense cover, and from a few centimeters to 2 or 3 m in Some of the world’s most floristically diverse regions, height. Human activities have modified most Euro- such as the mixed shrublands of the Mediterranean, pean scrub and grassland plant communities other South Africa, and southwestern Australia are now than those found on mountaintops or on very poor highly fragmented and suffer from impacts such as soils. In some cases, particularly where wetland dryland salinity and more frequent or intense fires. drainage or forest clearance for timber and farming has taken place, new scrub and grassland ecosystems 1. South African Fynbos Ecosystem have been created. Given their suitability for grazing animals and agri- One of the most biologically diverse and endangered of culture, it is not surprising that large areas of grass- all the world’s ecosystems is the fynbos shrublands of the southwestern and southern Cape of South Africa. lands have been converted from their natural state. In 2 eastern Europe, the steppe ecosystems have become Although relatively small in extent, the 470 km of the extremely rare and large areas of undisturbed steppes Cape Peninsula, including Table Mountain, are home are now found only in the south, where they border to 2285 different plant species, including one of the semidesert regions (north and west of the Caspian Sea, highest concentrations of endangered plant species. i.e., the Volga Delta and Terek region). The principal The fynbos is under serious threat from increasing ur- cause for the loss of scrub and grassland habitats over ban expansion (especially in the Cape Flats area) and the last 50 years has been the advent of widespread invasion by exotic weed species, including a number agricultural mechanization, which has resulted in the of Australian acacias. Similar shrubland communities cultivation of large areas of natural and seminatural can be found along the coastlines of the Mediterra- grassland. Remaining grasslands are isolated and nean, southwestern Australia, southern California, and highly fragmented, and usually restricted to steep Chile, and in each case they are considered to be ex- slopes and ground with thin soils. Increased use of tremely threatened. fertilizers and biocides has further threatened many species. The grassy plains of North America have been C. Inland Waters and Wetlands drastically reduced. The tallgrass prairies of the Amer- ican Midwest and Great Plains are a unique set of plant About half of all inland water and wetland habitats communities that once covered vast areas of the were lost during the twentieth century and even this ______ENDANGERED ECOSYSTEMS______7

TABLE II Some endangered scrub, grassland, and savanna ecosystems

Region Grasslands, savannas, and Deserts and xeric shrublands Mediterranean shrublands and shrublands woodlands

Africa Angolan escarpment woodlands Namib and Karoo Deserts Fynbos (South Africa) Zambezian flooded savannas and shrublands Ethiopian highlands Madagascar spiny desert Zambezian montane savannas and woodlands South African montane grasslands and shrublands Asia Terai-Duar savannas and Central Asian deserts grasslands (north Indian subcontinent) Red Sea fog woodlands

Australia Blue-grass grasslands Southwest Australia woodlands and Lowland temperate grasslands heaths Brigalow and Ooline scrubs Buloke and grassy white box woodlands (southeastern Australia) Europe and Russia Atacama Desert Mediterranean shrublands Latin America and Chilean matorral Caribbean North America Tallgrass prairies (United States) California chaparral and woodlands Everglades flooded grasslands

amount is exceeded in parts of North America, Eu- and biologically contaminated. Several rivers in rope, and Australia, primarily as a result of draining Colombia, including the Medelli´n and the Bogota´,are for intensive agriculture. Given the long agricultural almost totally devoid of life as a result of reductions and industrial history of Europe and the Mediterra- in dissolved oxygen. Other rivers, especially in areas nean region, it is not surprising that most of its wet- subjected to mining operations, are heavily contami- lands have been significantly modified or lost. Only in nated with toxic wastes and overburden. Large quanti- the extreme north do large wetland ecosystems remain ties of agricultural contaminants are disposed off in relatively intact. Of the more than 300 European and streams flowing into the Caribbean Sea, where there is Mediterranean wetlands of international importance clear evidence of elevated levels of phosphorus, nitrates, designated in the Ramsar Convention, 80% are con- potassium, pesticides such as DDT, and organic effluent. sidered to be threatened to some extent. Of major Pollution and saltwater intrusion also threatens ground- concern has been the continued loss and degradation water supplies across the wider Caribbean. In Venezuela, of freshwater habitats in the Mediterranean Basin, in- for example, the overuse of aquifers has resulted in a cluding many inland lakes and coastal lagoons and reduced flow of freshwater to nearby reef areas. estuaries. In Spain alone, more than 60% of all inland freshwater wetlands have disappeared during the last 1. Pollution of Wetland Ecosystems 25 years. The use of lake and river water for industrial purposes Large and relatively intact wetland ecosystems can often affects water quantity (when abstracting water) still be found throughout South America, the largest and and water quality (when reintroducing it as waste- most famous being those within the Amazon River water, sometimes polluted or of higher temperature). Basin. Even here, the rivers of this region are being inc- Many industries, such as pulp and paper production reasingly polluted by industrial and urban waste- and mining, wash large quantities of particulate matter waters from large industrial cities, wastewater from into lakes and rivers. Pollution and sedimentation mining industries, and agricultural runoff. As a result, threaten many inland waters and other wetlands. In many of the region’s water resources are now chemically some cases, the source of this pollution may be distant, 8 ______ENDANGERED ECOSYSTEMS______with contaminants being transported through the air its volume and its salinity level is now approaching in the form of industrial emissions. One of the best- that of seawater. Almost all the native organisms have known examples of this threat to wetland ecosystems died out. The 3.3 million ha of exposed seabed has was the acidification of European rivers and lakes, become a source of wind-borne salt and agricultural especially in the southern parts of Scandinavia. During residues that has now spread over surrounding areas. the 1950s and 1960s, at the peak of sulfur deposition, The five republics developed a water distribution the rate of acidification was several hundred times that agreement in 1992 and an Aral Sea Programme in of the natural process and thousands of Scandinavian 1995, which aims to stabilize the region and improve lakes became too acidic to support their original fish the management of the waters in the basin. A recent populations. Despite a decline in atmospheric pollu- collapse of agriculture in the region has since then lead tion over the last two decades and partial mitigation to some alleviation of the pressure on what was once through liming activities, acidification continues to one of the world’s largest inland wetlands. have detrimental effects on these lake ecosystems. The harmful increase in nutrient levels (eutrophi- 3. The Great Lakes and Everglades cation) occurs widely where the catchments of lakes With about 18% of the world’s fresh surface water, the and other wetlands are intensively farmed or densely Great Lakes system on the Canada–US border is one of populated. Fish-farming operations and sewage efflu- the most extensive freshwater ecosystems. Spanning ent discharge may also result in the eutrophication of more than 1200 km from east to west, the Great water bodies. As a result of increased nutrient levels Lakes—Superior, Michigan, Huron, Erie, and On- (most commonly nitrogen- and phosphate-based fer- tario—together with the St. Lawrence River system, tilizers or animal and human wastes), there is an in- are surrounded by large human populations and dense crease in phytoplankton production and microbial concentrations of industry. decay with consequent deoxygenation of the water and Beginning in the 1950s, concerns arose about the production of toxins. increasing eutrophication of the lakes, loss of wet- Marshes, bogs, and fens are a group of vegetated lands, and other habitats, the impact of exotic species wetlands that were once widespread in Europe. Since on native fish stocks and aquatic ecosystems, and early medieval times, however, these habitats have environmental contamination by persistent toxic been drained or mined for peat. Although some ex- chemicals. Major efforts to manage the lake system tensive areas of peatlands and similar ecosystems still have since done a great deal to restore environmental exist in the northern (boreal) and eastern regions of quality. Nutrient levels have been managed success- Europe, extensive areas of the original peatlands of fully and there has been a decline in the concentra- western Europe (including Scandinavia) have disap- tions of some toxic chemicals such as persistent peared. The vast marshy wetlands of Finland, for ex- organic pollutants derived from pesticides and indus- ample, have declined by about half, primarily as a trial processes. The flora and fauna of Lake Superior result of natural drying, drainage for agriculture, and have recovered and are again in good condition. The peat extraction. system remains in a fragile balance, however, and concentrations of many toxic chemicals remain high. 2. The Aral Sea Aquatic habitats and wetlands are still in a poor state The Aral Sea of southwestern Asia is one of the most overall, and the aquatic ecosystems of Lakes Michigan, threatened wetland ecosystems in the world, and will Ontario, and eastern Erie remain highly modified. require major international effort and cooperation to Equally famous are the Everglades of the Southeast restore it to a reasonable state of health. The Aral Sea is United States—the largest example of a rare flooded fed by the Amu Dar’ya and Syr Dar’ya Rivers, flowing grassland ecosystem. For the past 30 years, south Flor- from the mountains of Tian Shan and Pamirs. These ida has experienced an accelerated loss of this large and waters are the main source of water for Uzbekistan, unusual wetland complex. From the Kissimmee River, a Kyrgyzstan, Tajikistan, Turkmenistan, and the south- series of marshy oxbow lakes flow into Lake Okeecho- ern part of Kazakstan. Traditionally, about half of the bee, one of America’s largest freshwater lakes. Okeecho- water was used for irrigation and the other half flowed bee in turn feeds slowly into the Everglades itself, into the Aral Sea. Intensive development of cotton and known as the fabled ‘‘River of Grass.’’ To the south, the other irrigated crops over the last few decades has re- shallow estuary of Florida Bay once contained a very duced the inflow of these rivers to about 3% of former rich marine life, and an extensive coral reef system levels. Since 1960, the Aral Sea has lost two-thirds of thrived off the Florida Keys. Excessive consumption of ______ENDANGERED ECOSYSTEMS______9 water for agriculture and residential populations has led Endangered marine ecosystems are most obvious in to a decline in wading bird populations by some 90%, those parts of the world subject to extensive industri- and the Everglades have shrunk to a tiny fraction of alization, such as the North Atlantic Ocean and the what they were a half-century ago. Sea grass die-offs and Baltic, Caspian, Mediterranean, and other seas adja- massive algal blooms have contaminated much of the cent to Europe. Other ocean systems that would ap- previously clear waters of Florida Bay with silt, which pear to be at a high risk include the Sea of Japan, South now threatens to smother the coral reefs. An introduced China Sea, Caribbean Sea, and Gulf of Mexico. tree species of the genus Melaleuca is now widespread Although less threatened overall, the world’s oceans and has displaced some of the native flora. Altogether contain some of the least explored areas of the world, there are now some 55 federally listed endangered or and only a tiny percentage of the deep seabed has been threatened species in the area. subject to biological investigation. Nevertheless, studies have revealed a wealth of diverse ecosystem types in the 4. Wetlands of the Sunda Region deep sea, which include seamounts, cold water coral reefs, hydrothermal vents, deep-sea trenches, and sub- The rivers, lakes, and other freshwater habitats of the marine canyons. Of these, seamount ecosystems and lowland Sunda region (western Indonesia, Malaysia, cold water coral reef communities are particularly and Brunei) contain the most significant freshwater threatened by high-impact fishing methods, such as diversity of any Asian wetland ecosystem. Forest loss is bottom trawling. Coastal ecosystems and near-shore by far the most serious threat to these freshwater eco- marine areas are considered to be the most threatened systems as it disrupts the flow of nutrients, leads to of all ecosystem types. About 35% of mangrove eco- water temperature rise because of decreased shading, systems has been lost or converted, 20% of coral reefs and lowers concentrations of dissolved oxygen, result- have been destroyed, and up to 20% of coastal wetlands ing in conditions that are unsuitable for many fishes are lost in some places of the world on an annual basis. and freshwater invertebrates. Road construction, log- Studies of European marine systems show that land- ging, and shifting agriculture, particularly in mountain- based pollution and diffused sources of pollution are ous regions, result in soil erosion and thus increased the major causes of a general deterioration in water sediment loads in rivers, which further reduces water quality, from polychlorinated biphenyls (PCBs) in the quality. Hunting also represents a major threat to some Baltic to oil and pesticides in the Caspian. Organic aquatic species such as crocodiles and freshwater tur- wastes, including sewage, by-products from industries tles, in this ecoregion. Water pollution is a constant and (pulp and paper mills or tanneries), and fertilizers con- increasing pressure on many water systems. Part of this tained in runoff from agriculture, are common through- problem stems from increased motor traffic on the out European marine ecosystems. Three-quarters of the larger rivers, but chemical runoff from agriculture and region’s pollution originates from only three coun- the dumping of untreated waste into lakes and rivers tries—France, Spain, and Italy—and causes the con- are also major concerns. Tourism will also contribute to tamination of seafood and eutrophication of enclosed pollution if it is allowed to develop in an uncoordinated bays. Throughout the region, 80% of municipal sewage manner and scenic areas such as Lake Toba in northern is discharged untreated from coastal cities, and up to Sumatra are particularly vulnerable to pollution. 600,000 t of crude oil are released annually from oil- related operations and shipping. Agricultural runoff in D. Marine and Coastal Ecosystems the form of pesticides, including persistent organochlo- rinated compounds, contaminate the food chain, and Given that up to 60% of the world’s human population nitrate and phosphate runoff cause eutrophication and lives along the coast, it seems inevitable that many increased episodes of algal growth, including the poi- highly diverse and productive coastal ecosystems sonous ‘‘red tides.’’ Chemical pollution, bottom-trawl- should be particularly threatened. Early human settle- ing fishing practices, and the introduction of exotic ments were common along coastlines as they offered a species have contributed to the depletion of indigenous combination of marine- and land-based sources of marine life, such as Posidonia (sea grass) meadows. food, navigable rivers, and access to maritime trading Increasingly, overfishing is being implicated as a routes. With the advent of industrial development, threat to marine ecosystems, particularly in areas such coasts also offered a superficially simple solution to as the North Sea, which are subject to intensive exploi- the growing human populations and their wastes, tation. Depletion of commercial fish populations may namely, dumping in large coastal rivers. cause changes in the species composition and adversely 10 ______ENDANGERED ECOSYSTEMS______affect populations of birds, seals, and cetaceans that feed 2. Coastal Ecosystems of Eastern Africa on these species. In addition to depletion of fish stocks, Coastal marine ecosystems in eastern Africa are some fishing techniques have a direct impact on non- biologically diverse, but they are also increasingly target populations. Trawling or dragging of fishing gear, threatened by expansion of coastal populations and for example, can have devastating local impacts on development. Corals form an almost continuous benthic ecosystems such as the rare Norwegian coral fringing reef along the entire coastline of eastern Af- communities (Paragorgia arborea) or the diverse com- rica. The western coasts of the islands of Zanzibar, munities associated with the horse mussel (Modiolus Pemba, and Mafia are characterized by patch reefs, modiolus) at Strangford Loch in Scotland. In many parts whereas well-developed fringing reefs predominate on of the world, other fishing techniques have also severely the eastern sides. One of the most biologically diverse damaged marine ecosystems. Drift netting is particularly areas—the Bazaruto Archipelago in Mozambique— notorious for the high by-catch of species such as sea supports a range of marine habitats, including deep- turtles, cetaceans, and seals, whereas long-line fishing sea areas, coral reefs, rocky intertidal areas, sandy has been responsible for the deaths of tens of thousands beaches, tidal sand flats, sea grass meadows, and of albatross and other seabirds in southern oceans. The mangrove communities. Marine turtles and many spe- trawling of seamounts has the potential to destroy these cies of marine mammals are found in these coastal unique ecosystems and their numerous unusual, and waters, including the highly threatened dugong restricted species. (Dugong dugon). The mangroves are spawning nurs- ery habitats for many fish and crustacean species, and 1. The Wadden Zee provide an invaluable ecological service by filtering More than 70% of the European coastline is con- riverine sediments that can damage nearby coral reefs. sidered to be under a high degree of threat. Threats to Environmentally harmful fishing practices, such as coastal and marine ecosystems arise from a wide dynamite fishing as well as overfishing, pollution, and variety of human impacts and vary considerably in uncontrolled tourism development, threaten the sur- different parts of the world. In the temperate and in- vival of these reefs and other coastal ecosystems dustrialized regions, areas such as the Wadden Zee throughout the region. along the Netherlands coast show the effects of many centuries of human impact. Much of the biological richness of the Wadden Zee derives from its mudflats 3. Island Ecosystems (waddens), which appear to be decreasing as a result Islands are particularly susceptible to invasion by ex- of the construction of dykes and barriers that affect not otic species or rapid depletion of their resources fol- only the immediate vicinity but also the flow and di- lowing human colonization. Some island ecosystems rection of water currents and sedimentation patterns. have evolved in long isolation from nearby landmasses Pollution and eutrophication, caused by synthetic and may contain many unique plant and animal spe- organic substances, heavy metals, oil, and a surplus cies. They are also the breeding grounds for many of nutrients, have been identified as a major threat to marine species, such as turtles, seals, and seabirds that the area’s wildlife populations. The use of tributyl tin may be vulnerable to predators. In some cases, birds (TBT) as an antifouling agent in paint has resulted in a have become flightless as a result of the absence of sharp decline of two species of whelk. Shorebirds are predators, making them especially vulnerable should threatened by oil spillages in the Wadden Zee, and humans or exotic species arrive. It is not surprising pollutants such as chlorinated hydrocarbons have then that most animal and plant extinctions that have caused reduced breeding success among common tern occurred in historic times have been of island species. (Sterna hirundo) populations. High levels of pollutants Islands that are of particular concern for both their may also interfere with the immune systems of certain significant biological richness and vulnerability to hu- species, and in 1988 a large number of harbor seals man impact include those of New Caledonia, Hawaii, died from a viral outbreak. Many of the region’s nat- Madagascar, and the Gala´pagos Islands. ural resources have been overexploited, and as early as Although the overall rate of island deforestation the end of the nineteenth century native oysters began appears to have slowed down in the last decade, an- to disappear. Natural mussel beds have also dramat- nual deforestation on islands is almost three times the ically declined, and in large parts of the Wadden Zee world average rate. The main causes of deforestation mechanized cockle fisheries continue to disturb the include conversion for agricultural use and for infra- mud surface. structure development such as roads, ports, housing, ______ENDANGERED ECOSYSTEMS______11 and tourism development. Loss of forests in island coral reefs occupy a small fraction (o0.2%) of the total systems often has more serious impacts on biodiversity area of the world’s oceans, they are among the most than forest loss elsewhere due to their smaller extent, biologically diverse of all ecosystems. Formed by the and the presence of endemic species and unique accumulation of calcium carbonate deposited by cer- ecosystems. tain coral species over thousands of years, coral reefs The Gala´pagos Islands represent one of the most cover some 600,000 km2 and are the largest structures outstanding examples of the evolutionary processes that formed by living creatures. The destruction of coral influence isolated island ecosystems, as well as suscep- reefs is caused by many human activities, ranging from tibility to human impacts. Across the many individual coastal development and destructive fishing practices islands of the Galapagos group arid lowlands of open to overexploitation of resources, marine pollution, and cactus forest, transitional subtropical forest, moist runoff from agricultural activities and deforestation. A dense forest at higher elevations, and treeless upland number of reefs of particular biological interest are also areas covered with ferns and grasses can be found. under the most serious threat, including almost all the Habitat destruction and degradation from grazing by reefs of the Philippines and coral communities in introduced goats, sheep, and cattle, as well as uncon- coastal Indonesia, Tanzania, the Comoros, and the trolled fires, are a major threat. Introduced pest species Lesser Antilles in the Caribbean. such as rats and cats prey on native species. Poaching of Of all the world’s ecosystems, coral reefs may be the rare and threatened species is increasing, as is the over- most vulnerable to the effects of climate change. Blea- exploitation of many marine species such as sea cu- ching does not automatically kill corals, but successive cumbers (Ischitopus fuscus) and sharks. Tourism and bleaching events in close proximity, or prolonged settlement from the mainland pose additional pressures bleaching events, often do lead to mass mortality. on an already stressed ecosystem. Some recovery may occur given sufficient time be- tween bleaching episodes, and B40% of the reefs that 4. Mangrove Ecosystems were seriously damaged in the 1998 coral bleaching events are either recovering well or have fully Under the right conditions, extensive mangrove forests recovered. Climate change also has other detrimental can be found throughout the tropics in shallow bays impacts on coral. For example, rising carbon dioxide and inlets and along rivers. These biologically rich levels change the pH of water, reducing calcium car- communities have been subjected to enormous pres- bonate deposition (reef building) by corals. Climate sure from human settlement. By 2001, it was estimated change also facilitates the spread of pathogens leading that about one-third of the world’s mangroves had to the spread of coral diseases. It has been suggested been destroyed. The main reasons for this loss in the that climate change will reduce the world’s major coral past have been felling for firewood or the production reefs in exceedingly short time frames with one esti- of charcoal. The rapidly expanding shrimp aquacul- mate suggesting that all current coral reefs will disap- ture industry represents a new and increasing threat to pear by 2040 due to warming sea temperatures. the world’s remaining mangroves. The clearing of Even coral reefs in developed countries are not im- mangrove forests to make way for shrimp ponds is mune to human impacts. The Nansei Shoto Islands, a responsible for about half of all the mangrove loss in chain of 200 islands off southwestern Japan, for exam- recent years, and has greatly reduced the extent of ple, contain some of the most extensive and biologically mangroves in Southeast Asia, South Asia, and Latin diverse coral reefs in the western Pacific. The relative America. Thailand has lost more than half of its isolation of the islands’ marine and terrestrial ecosys- mangrove forests since 1960 as a result of the booming tems has produced unusual patterns of endemism. On shrimp aquaculture industry. In Ecuador, estimates of Shiraho reef there are at least 120 species of coral, in- mangrove loss range from 20% to nearly one-half of cluding the oldest and biggest community of blue coral Ecuador’s original 362,000 ha of mangrove forest. Typ- (Heliopora coerulea) in the Northern Hemisphere and ically, the shrimp ponds are abandoned after a few extensive colonies of the massive porous coral (Porites years and new areas have to be cleared. australiensis), Madracis coral (genus Madracis), and staghorn coral (family Acroporidae), as well as more 5. Coral Reefs than 300 species of fish. These coral reef ecosystems It is estimated that B20% of the world’s coral reefs have have become seriously threatened since 1972, with up been destroyed and more than a further 20% badly to 90% lost as a result of silt runoff from construction, degraded or under imminent risk of collapse. Although farming, and logging activities. 12 ______ENDANGERED ECOSYSTEMS______

6. Other Endangered Coastal Ecosystems threaten ecosystems can be seen as falling into three A variety of ecosystems can be found in the coastal zone categories: factors that reduce the extent of an depending on geographic location and the local phys- ecosystem, factors that alter the species composition ical environment, including sand dunes, coastal wet- of an ecosystem, and factors that disturb ecosystem lands and lagoons, sea grass beds, salt marshes, and processes. Many ecosystems are at the point of disap- mudflats. These ecosystems are among the most re- pearing, or being irreparably modified. Table III gives a stricted in extent, as well as highly threatened by coastal summary of threats to major ecosystem types. development, pollution and human exploitation. Ecosystems can be considered endangered when Sand dunes are unique ecosystems occurring at the their extent, species composition, or the natural proc- margins of the land and sea, founded upon the sands esses that sustain life become sufficiently disrupted or that are washed up by the movements of the sea. In degraded. The difficulty in describing the exact extent Europe there are o428,000 ha of dunelands remaining and status of an ecosystem, however, makes precise on Atlantic coasts and widespread planting with exotic assessment of their conservation status much more species has changed their character. The situation is difficult than it is for a species of organism. In more acute along the southern European coastline, particular, the conservation status of an ecosystem where sandy beaches are the main attraction for many depends greatly on the scale at which the ecosystem is of the 100 million tourists who visit the Mediterranean considered. From the major global biomes such as each year. Construction of coastal towns and resorts tropical forests, or deserts, to the regional and local has resulted in an estimated 71% loss in dune areas scale, various threats operate that affect the likely per- since 1900. sistence of that ecosystem, or its components. The Salt marshes and coastal peat swamps have also ecoregional approach developed in the late 1990s undergone massive change and destruction, whether (Olson and Dinerstein, 1998) is now a widely used they are within estuarine systems or along the coast. approach for classifying, assessing, and managing eco- Salt marsh subsidence has occurred in part due to re- systems at the regional scale—combining environ- stricted sediment delivery from watersheds. Peat mental and geographic attributes to identify specific swamps in a number of Southeast Asian countries regions of high biodiversity. have declined from 46% to 100% in countries mon- itoring changes. Rocky intertidal, nearshore mudflats, 2. Conversion of Ecosystems for Food Production deltas, beaches, and dunes also provide ecosystem services such as food, shoreline stabilization, mainte- The recent expansion of mechanized agriculture nance of biodiversity (especially for migratory birds), has been the main factor in a rapid conversion and and recreation. In the United States, the rocky inter- loss of terrestrial ecosystems. Large areas of forest, tidal zone has undergone major transformation in the woodland, and grassland have been destroyed follow- last few decades: the California mussel (Mytelus cali- ing the early expansion of agriculture, starting in fornianus) has become very rare, the sea star Pisaster southwestern Asia, China, the Mediterranean, and Eu- sp. is now almost never seen. The once abundant black rope and in the past 100 years North and South Amer- abalone (Haliotis cracherodii) can no longer be found ica, and Australia. Many temperate ecosystems are in southern California and dozens of formally abun- now endangered as a result. Similar trends are now dant nudibranch species are now rare. Similar trends obvious in the tropical regions of the world, exacer- have been observed elsewhere in the world. Along the bated by poor forestry practices and the replacement Yellow Sea coast, China has lost around 37% of habitat of forests with cash crops. Even where natural in intertidal areas since 1950, and South Korea has lost ecosystems have not been subject to deliberate mod- 43% since 1918. ification, human impacts are detectable as a result of exploitation, pollution, and the presence of foreign species. III. THE CONSERVATION OF ECOSYSTEMS Within the marine environment, near-shore ecosys- tems such as coastal, island, and coral ecosystems are A. Global Drivers of Ecosystem Change the most threatened. In the open oceans it has become apparent in recent years that certain deep-water 1. The Major Human Impacts on Ecosystems ecosystem types such as seamounts and deep-water The conservation of ecosystems depends on the corals are also threatened, particularly as a result of management of human-induced impacts. Factors that destructive fishing practices such as bottom-trawling. ______ENDANGERED ECOSYSTEMS______13

TABLE III Threats to the world’s major ecosystem types

Ecosystem type Main threats

Tropical moist forests Clearing for agriculture and plantations, large-scale forestry operations, development of roads, towns, and other urban infrastructure, fire. Temperate forests Clearing for agriculture and plantations, large-scale forestry operations, development of roads, towns, and other urban infrastructure, fire, introduced exotic species, air pollution. Boreal forests Large-scale forestry operations, fire, development of roads, towns, and other urban infrastructure Tropical woodlands and savannas Clearing for agriculture and plantations, irrigated crops, pastoral development and grazing by domestic stock, feral animals (e.g., goats), development of roads, towns, and other urban infrastructure, fire, introduced exotic species. Temperate woodlands Clearing for agriculture and plantations, large-scale forestry operations, development of roads, towns, and other urban infrastructure, fire, introduced exotic species, air pollution. Scrubs and grasslands Clearing for agriculture and plantations, irrigated crops, pastoral development and grazing by domestic stock, feral animals (e.g., goats), development of roads, towns, and other urban infrastructure, fire, introduced exotic species. Deserts Large-scale irrigation developments, changes in water regimes (e.g., water extraction for irrigation), changes in fire regimes, introduced plant and animal species, urban encroachment. Tundra and ice sheets Pollution (land and marine), climate change. Freshwater wetlands Water extraction, pollution (especially eutrophication, persistent organic pollutants, and heavy metals), drainage and altered flows, large-scale dams and weirs, urban development, introduced species (especially nonnative fish, invertebrates, and water plants). Coasts and shallow seas Direct impacts from dredging and reclamation, coastal development and urban infrastructure (including cities, ports, and harbors), marine and land-based sources of pollution, introduced marine organisms, climate change (especially for coral reefs and coastal wetlands), overfishing and destructive fishing practices (e.g., dynamite and cyanide fishing, bottom trawling). Oceans Marine pollution (including oil pollution and dumping of toxic chemicals), overfishing, and destructive fishing practices.

Efforts to conserve ecosystems are being made There is an urgent need to improve our knowledge throughout the world, but these are often hampered by of the distribution and conditions of the world’s conflicting land-use issues and a general lack of ecosystems. Current national and international in- understanding of ecosystem processes. At the global itiatives for developing habitat classifications and eval- level, international conventions and agreements have uation methodologies need further coordination. The established a legal framework for ecosystem cons- information that is available points to the inescapable ervation. Following the development of the CBD in fact that the extent and quality of remaining natural 1992, many countries have begun the task of classi- ecosystems are in decline and in certain cases this de- fying ecosystems and determining threats. Assess- cline is accelerating. ments of the progress in achieving the goals and targets of the CBD indicate that the conservation of 3. Changes in Species Composition of Ecosystems natural ecosystems will require much greater action at Apart from complete destruction, most of the world’s a variety of levels, from international to local, and will remaining natural ecosystems show some effects of require a fundamental change in the patterns of re- human intervention. Commonly, these are factors that source exploitation and consumption. alter the distribution or abundance of species within Nearly 60 years after the development of the con- an ecosystem. Although species populations con- cept of an ecosystem, it is now apparent that many stantly change, disruptions to these natural cycles have been lost through human activities, or so signi- can have widespread effects. Certain species, for ex- ficantly altered that they may be considered end- ample, are referred to as ‘‘keystone’’ species because of angered. Our understanding of ecosystems has their vital role in maintaining the populations of other changed profoundly, with much greater recognition species (e.g., they may pollinate flowers or be large now given to their dynamic and complex nature and predators). When such changes affect the so-called the potential for human activities to change their keystone species, then larger impacts may be observed biological and physical components. in the rest of the ecosystem. Extensive hunting, the 14 ______ENDANGERED ECOSYSTEMS______harvesting of timber, grazing of livestock, exploitation effort directed toward ecosystem conservation is there- of fisheries, and other natural resources, often affect fore increasingly focused on the maintenance of ecosys- populations of keystone species and thus alter natural tem resilience (Walker, 1995). ecosystems, sometimes to the point where they can no In extreme cases, the species composition of an ec- longer sustain their original plants and animals. osystem or its natural processes may be so disturbed The deliberate or accidental spread of exotic animals from the original that they do not appear to be capable and plants also disrupts the ecosystem as these new of recovery. Such disturbance may occur, for example, predators or competitors flourish at the expense of the with the loss of nutrients, soils, or water supply. A original species. The pollution of land, water, and air good example of changes in ecosystems brought about may affect ecosystems by introducing additional nutri- by disruptions in natural processes can be seen in case ents or toxic substances into food chains, causing deaths of fires. Many ecosystem types (particularly some open or reduced reproductive success and consequent forest, shrubland, and grassland communities) are changes in species composition. The cumulative impact adapted to frequent fires and their species may exhibit of these factors can often be observed at some distance a range of responses to the latter, that ensure their or point of time from the original impact. The modi- survival and continuation. On the other hand, ecosys- ficationofariverhighinthemountains,forexample, tems such as temperate and tropical rain forests may may eventually affect the water quantity and quality be extremely susceptible to fires and the subsequent reaching a coastal marine ecosystem, changing that loss of nutrients that follows heavy rains and leaching. ecosystem and in turn affecting the viability of coastal One of the earliest responses to the loss of ecosys- communities. In such cases it may be possible to manage tems was the development of national parks and other these uses sustainably, and even to restore and rehabil- protected areas. Originally established largely as a itate many of the attributes of the original ecosystem. means of providing outdoor recreation for increasingly urbanized societies, protected areas now fulfill many 4. Climate Change Impacts on Ecosystems important functions. One of the most important func- The effects of climate change will pose new threats to tions of a protected area system is to safeguard a re- natural ecosystems, particularly those at the edge of presentative sample of major ecosystems from their climatic tolerance. Species composition might development, and most countries now have some change rapidly as specialized species are replaced by form of protection for achieving this goal. It has be- more generalist species able to take advantage of come clear, however, that protected areas cannot changing conditions. Of course change is a natural provide sufficient ecosystem protection in isolation part of evolution and ecosystems should not be con- from other measures. In particular, as ecosystems be- sidered as static and unchanging in time. As continents come fragmented, many of the ecological processes drift over millennia, climates change, and species that sustain these areas degrade, and resilience is lost. evolve and disappear, ecosystems are constantly being Pollution, soil erosion, the invasion of exotic species, modified. However, it is the pace at which climate and changes in the frequency or intensity of fires can change is now occurring that threatens the capacity of all have an impact on the viability of all but the largest ecosystems to respond and adapt. protected area. Ecosystem conservation needs to take Ecosystems that exist within a narrow geoclimatic into account all of these factors, and this is one reason range are expected to be those most at risk from cli- why planning models such as the ecoregion approach mate change. Coral reefs may be the earliest and most are being adopted. obviously impacted ecosystems as a result of temper- Legal protection and management are clearly nec- ature-induced coral bleaching. Other ecosystems at essary in many cases to halt the rapid loss of ecosystem obvious risk include alpine and polar ecosystems types. Although the first stated goal of the US End- where temperature increases are likely to result in loss angered Species Act is ‘‘to provide the means whereby of snow cover, the extinction of cold-adapted species, the ecosystems upon which endangered species and and increased invasion by warm-tolerant species. threatened species depend may be conserved,’’ it is clear that even this relatively powerful legislation has 5. Ecosystem Resilience only limited ability to achieve the aim of ecosystem The successful maintenance, protection, and restoration conservation. The situation is obviously much more of endangered ecosystems will depend to a significant difficult in many poor and developing countries. In degree on the extent to which they remain resilient many cases, the intent of environmental law vastly to negative change from human impacts. Much of the exceeds the willingness or capacity of the country to ______ENDANGERED ECOSYSTEMS______15 effectively implement its provisions. In such cases, ENDANGERED REPTILES AND AMPHIBIANS  ENDANGERED international agencies, organizations, and funding TERRESTRIAL INVERTEBRATES  MARINE ECOSYSTEMS bodies are required to help build this capacity and to provide training and institutional strengthening. International treaties and conventions, such as the Bibliography CBD, established as a result of the 1992 Earth Summit, Myers, N. (1997). Threatened biotas: ‘‘Hot spots’’ in tropical forests. provide an important framework and guidelines for The Environmentalist 8, 187–208. such international cooperation. Olson, D. M., and Dinerstein, E. (1998). The Global 200 A repre- sentation approach to conserving the Earth’s most valuable ecoregions. Conserv. Biol. 12, 502–515. See Also the Following Articles Reid, W. V., Mooney, H. A., Copper, A., et al. (2005). Millenium Ecosystem Assessment Synthesis Report. Millenium Assessment ENDANGERED BIRDS  ENDANGERED FRESHWATER and World Resources Institute, Washington, DC. INVERTEBRATES  ENDANGERED MAMMALS  ENDANGERED Walker, B. (1995). Conserving biological diversity through ecosys- MARINE INVERTEBRATES  ENDANGERED PLANTS  tem resilience. Conserv. Biol. 9, 747–752.