Hotspots

HOTSPOTS Norman Myers

Green College, Oxford University

I. II. III. IV. V. VI. VII. VIII.

Introduction Biodiversity Hotspots as Originally Identified Revised and Expanded Hotspots Analysis Main Findings of Revised Hotspots Analysis Wilderness Areas High-Value Ecosystems Megadiversity Countries The Conservation Impact of Hotspots

of extant species. Identification of the world’s hotspots—roughly 18–25 in number, depending on the criteria employed—provides a means of focusing on those areas where threats to biodiversity are most extreme and conservation efforts can be most effective. Underlying this approach is the thesis that present conservation resources are not sufficient to maintain all threatened species and thus global priorities need to be established.

GLOSSARY biodiversity Popularly supposed to refer to the spectrum of all species on Earth, the concept should also include species’ subunits (genetic diversity) and the diversity of ecosystems and ecological processes. endemics Those species that are limited to relatively small areas, being found nowhere else on Earth. hotspots Those areas that (a) feature exceptional concentrations of endemic species and (b) face imminent threat of habitat destruction. megadiversity Phenomenon of at least 70% of all species being confined to 17 ‘‘megadiversity’’ countries.

HOTSPOTS are specific areas of the Earth’s land surface that have a disproportionately large number

I. INTRODUCTION We are witnessing the opening phase of a mass extinction episode that, if allowed to persist, could well eliminate a large proportion of all species among other forms of biodiversity within the foreseeable future (Myers, 1993; Wilson, 1992). We do not have nearly enough conservation resources (funds, scientific skills, and the like) to assist all species under threat, and as the biotic crisis gathers momentum the shortfall will become ever more severe. This predicament places a premium on priority planning. Which conservation strategies offer the biggest payoff? Or, to be more precise: How can we save the most species at the least cost? This key question is likely to remain at the forefront of conservation endeavors as the Earth’s biotic crisis grows worse. By concentrating on a few critical areas where needs are

Encyclopedia of Biodiversity, Volume 3 Copyright  2001 by Academic Press. All rights of reproduction in any form reserved.

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greatest and where the payoff from safeguard measures would also be greatest, conservationists can engage in a more systematized response to the challenge of largescale extinctions that lie ahead. This represents a focused silver bullet response, in contrast to the scattergun approach that has characterized much conservation activity to date. This is not to say—and the point is emphasized— that biodiversity outside of species-rich areas should be ignored. The biodiversity of any country is vitally important to that country’s environmental well-being. A number of responses have been proposed. The ‘‘hotspots’’ thesis is one such mode of setting priorities at a time when we need to determine priorities with more scientific acumen than ever. This approach identifies areas that feature exceptional concentrations of endemic species and that face exceptional threat of imminent habitat destruction (Myers, 1988, 1990; Myers et al., 2000). A hotspots strategy can be complemented with measures that highlight ‘‘megadiversity’’ countries, that is, those few countries that harbor most of the world’s species, whether threatened or not (Mittermeier and Mittermeier, 1997). A further backup strategy is the protection of wilderness areas, being extensive tracts of little-disturbed wildlands with rich biodiversity stocks where conservationists can ‘‘get it right’’ from the start. Still a fourth response would focus on ‘‘high-value’’ ecosystems that, while not harboring unusual concentrations of species, encompass other remarkable manifestations of biodiversity. We shall consider each of these strategies, while giving most attention to the most promising option, the conservation of hotspots.

II. BIODIVERSITY HOTSPOTS AS ORIGINALLY IDENTIFIED The hotspots strategy was first raised in the late 1980s, when an exploratory listing of hotspots identified 18 localities, 14 in tropical moist forests and 4 in Mediterranean-type zones (Myers, 1988, 1990). The analysis centered on higher plant species alone, with the assumption that these would serve as acceptable indicator taxa for other categories of species (mammals, birds, and other vertebrates, plus invertebrates). Analysis revealed that at least 20% of all plant species were confined to areas comprising 0.5% of Earth’s land surface—areas that for the most part have already lost the bulk of their biodiversity habitats.

III. REVISED AND EXPANDED HOTSPOTS ANALYSIS A more recent effort focusing on 25 biodiversity hotspots (Table I) has sought to refine and expand the original hotspots analysis by including other taxa and biomes (Myers et al., 2000). It has centered not only on higher plants but also on birds, mammals, reptiles, and amphibians as indicators of vertebrate taxa. In addition, it has extended ecozone coverage to include tropical dry forests, woodlands, savanna and open savanna, temperate moist forests, grasslands, and arid lands. This expanded approach still omits invertebrates from consideration, which is regrettable in that invertebrates comprise the great majority of all species, at least 95% and possibly 99%. Future analysis could be extended to include butterflies as indicators of invertebrate hotspots. Butterflies are more closely tied to plant communities than vertebrates, and yet are popular enough with amateur naturalists that for some areas we have quite accurate records of their populations through time. (As a bonus factor, butterflies are sometimes the best single group of animals as indicators of ecosystem health.) Additional support for invertebrate hotspots could be gained from focusing on dragonflies, damselflies, and tiger beetles, all of which are widespread and fairly well known. This latest hotspots analysis, like the earlier one, is limited to terrestrial biotas. It is also based on vascular or higher plants (which comprise around 90% of all plants, and are hereafter referred to as ‘‘plants’’), since they are essential to virtually all forms of animal life. These plants are well known, with their conservation status adequately documented for the most part. The endemism data tend to be minimal for two reasons. One is the sheer lack of recent documentation in the form of, for example, modern floras. For instance, there is no up-to-date account of Brazil’s plant species even though the country is believed to harbor 50,000 species or one-sixth of the world’s total. More importantly, endemism statistics almost always relate only to individual countries or parts of countries, whereas 12 of the hotspots extend across two or more countries and 6 hotspots across four or more. In these cases, it has been singularly difficult to compute totals for hotspot-wide endemics with cross-boundary complications, and the analysis (Myers et al., 2000) has usually had to depend on best-judgment estimates by scientists with extensive on-ground experience. These estimates tend to be cautious and conservative, meaning that the

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HOTSPOTS TABLE I The 25 Biodiversity Hotspotsa

Hotspot

Original extent (km2)

Remaining primary vegetation (km2) (% of original extent)

Area protected (km2) (% of hotspot)

Endemic plants Endemic vertebrates (% of global (% of global Plant plants total, Vertebrate vertebrates species 300,000) species total, 27,298)

Tropical Andes Mesoamerica

1,258,000 1,155,000

314,500 (25.0) 231,000 (20.0)

79,687 (25.3) 138,437 (59.9)

45,000 24,000

20,000 (6.7%) 5000 (1.7%)

3389 2859

1567 (5.7%) 1159 (4.2%)

Caribbean Brazil’s Atlantic Forest Choco/Darien/ Western Ecuador Brazil’s Cerrado Central Chile

263,500 1,227,600 260,600

29,840 (11.3) 91,930 (7.5) 63,000 (24.2)

29,840 (100.0) 33,084 (35.9) 16,471 (26.1)

12,000 20,000 9000

7000 (2.3%) 8000 (2.7%) 2250 (0.8%)

1518 1361 1625

779 (2.9%) 567 (2.1%) 418 (1.5%)

1,783,200 300,000

356,630 (20.0) 90,000 (30.0)

22,000 (6.2) 9167 (10.2)

10,000 3429

4400 (1.5%) 1605 (0.5%)

1268 335

117 (0.4%) 61 (0.2%)

California Floristic Province

324,000

80,000 (24.7)

31,443 (39.3)

4426

2125 (0.7%)

584

71 (0.3%)

Madagascarb Eastern Arc and Coastal Forests of Kenya/Tanzania Guinean Forests of West Africa Cape Floristic Province Succulent Karoo Mediterranean Basin Caucasus

594,150 30,000

59,038 (9.9) 2000 (6.7)

11,548 (19.6) 2000 (100.0)

12,000 4000

9704 (3.2%) 1500 (0.5%)

987 1019

771 (2.8%) 121 (0.4%)

1,265,000

126,500 (10.0)

20,324 (16.1)

9000

2250 (0.8%)

1320

270 (1.0%)

74,000

18,000 (24.3)

14,060 (78.1)

8200

5682 (1.9%)

562

53 (0.2%)

112,000 2,362,000 500,000

30,000 (26.8) 110,000 (4.7) 50,000 (10.0)

2352 (7.8) 42,123 (38.3) 14,050 (28.1)

4849 25,000 6300

1940 (0.6%) 13,000 (4.3%) 1600 (0.5%)

472 770 632

45 (0.2%) 235 (0.9%) 59 (0.2%)

Sundaland Wallacea Philippines

1,600,000 347,000 300,800

125,000 (7.8) 52,020 (15.0) 9023 (3.0)

90,000 (72.0) 20,415 (39.2) 3910 (43.3)

25,000 10,000 7620

15,000 (5.0%) 1500 (0.5%) 5832 (1.9%)

1800 1142 1093

701 (2.6%) 529 (1.9%) 518 (1.9%)

Indo-Burma South-Central China Western Ghats/Sri Lanka SW Australia

2,060,000 800,000 182,500

100,000 (4.9) 64,000 (8.0) 12,450 (6.8)

100,000 (100.0) 16,562 (25.9) 12,450 (100.0)

13,500 12,000 4780

7000 (2.3%) 3500 (1.2%) 2180 (0.7%)

2185 1141 1073

528 (1.9%) 178 (0.7%) 355 (1.3%)

309,850

33,336 (10.8)

33,336 (100.0)

5469

4331 (1.4%)

456

100 (0.4%)

New Caledonia New Zealand Polynesia/Micronesia

18,600 270,500 46,000

5200 (28.0) 59,400 (22.0) 10,024 (21.8)

526.7 (10.1) 52,068 (87.7) 4913 (49.0)

3332 2300 6557

2551 (0.9%) 1865 (0.6%) 3334 (1.1%)

190 217 342

84 (0.3%) 136 (0.5%) 223 (0.8%)

17,444,300 2,122,891 (12.2)

800,767 (37.7)

**c

133,149 (44%)

**c

9645 (35%)

Total a

Choco/Darien/Western Ecuador stretches from the Darien of Panama to Western Ecuador; Cape Floristic Province lies in the southern sector of South Africa; the Succulent Karoo lies in western South Africa; Sundaland encompasses the islands of western Indonesia together with the Malay Peninsula; and Wallacea includes islands of eastern Indonesia. b Madagascar includes the nearby islands of Mauritius, Reunion, Seychelles, and Comores. c These totals cannot be summed due to overlapping between hotspots. Source: Myers, et al., 2000.

true totals will likely be higher than those presented here. To qualify as a hotspot, the main determining criterion is species endemism. A second criterion is degree of threat; to qualify, an area must retain only 30% or less of its original primary vegetation. The cutoff adopted is

1500 endemic plant species, or 0.5% of the 300,000 plant species on land (Prance et al., 2000). Unlike the earlier hotspots analysis, the expanded version includes birds, mammals, reptiles, and amphibians. It excludes the only other vertebrate group, fishes (totaling roughly half of all vertebrates), because data

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about their numbers, habitats, and conservation status are generally poor. Hereafter, the term ‘‘vertebrates’’ refers to all vertebrates except fishes. Not that vertebrates serve as a second determinant of hotspot status; if an area qualifies by the 0.5% plants criterion, it makes the list. Vertebrates are strictly used for backup support and to determine measures of congruence. Sixteen hotspots contain at least 130 vertebrate endemics, or 0.5% of the 27,298 species of the four vertebrate groups worldwide, while 12 of these contain at least twice as many. As noted, the analysis omits insects and other invertebrates. While scientists have documented the great majority of plants and vertebrates, they have documented only a tiny proportion of invertebrates. For present purposes and purely as a working proposition, it is reasonable to assume that the five categories of endemic species documented here are roughly matched by similar concentrations of endemic invertebrate species. Although this assumption is preliminary and approximate, it is supported by more evidence in its favor than against. Many of the hotspots have already lost 90% of their original primary vegetation, and a few of them, for example, the Mediterranean Basin, Indo-Burma, and the Philippines, have lost at least 95%. It is true that disrupted and secondary vegetation can sometimes support moderate numbers of original species, but in the main this is not significant for conservation purposes. Constraints of socioeconomic status, political commitment, or conservation feasibility in the countries concerned have not been considered. This is partly because these factors are difficult to quantify, and partly because they can be better incorporated when designing conservation projects. All the same, it is worth noting that Nepal, for instance, hardly possesses the administrative structures, the managerial know-how, or the planning capacities that can usefully absorb additional external assistance. Related questions formerly arose with respect to Zaire (now the Democratic Republic of Congo): Should that country have been granted conservation support when its military spending was twice as large a proportion of its gross domestic product as the average for sub-Saharan Africa, and when the personal wealth of President Mobutu was greater than the entire country’s economy?

IV. MAIN FINDINGS OF REVISED HOTSPOTS ANALYSIS A total of 25 hotspots contain the remaining habitats of 133,149 plant species (44% of all plant species) and

of 9645 vertebrate species (35% of all such species). These endemics are confined to an aggregate area equivalent to 1.4% of Earth’s land surface (Table I). The hotspots are so threatened that, having already lost at least 70% of their original primary vegetation, they all seem likely, in the absence of greatly increased conservation efforts, to lose much if not most of their remaining vegetation within the foreseeable future. The 25 hotspots feature a broad range of ecosystem types. Predominant are tropical rain forests (in 15) and Mediterranean-type zones (in 5). Nine are mainly or completely made up of islands; almost all tropical islands fall into one or another hotspot. Sixteen hotspots are in the tropics, which largely places them in developing countries where threats are greatest and conservation resources are in shortest supply. Now consider the relationship of endemic species to total species. In the 17 ‘‘megadiversity’’ countries with some 70% of Earth’s species, the ratio of endemic nonfish vertebrates to all vertebrates ranges from a high of 1 : 1.3 for Madagascar to a low of 1 : 14 for the Democratic Republic of Congo (formerly Zaire). When all 25 hotspots are considered, the average ratio is 1 : 2.8. This high ratio of endemism demonstrates the significance and rarity of the biodiversity found in these hotspots. Still more significant, the extent of habitat loss in the hotspots means that we can reasonably assume they harbor an even greater share of threatened species, defined here as Red Data Book species (these species are assessed by the World Conservation Union and include only species known to science and known to be threatened; the true total is far higher). So far as we can calculate, albeit in a preliminary and exploratory manner, the number of threatened species occurring in hotspots probably amounts to roughly two-thirds of all threatened species.

A. The ‘‘Hotter’’ Hotspots Some hotspots are ‘‘hotter’’ than others. In nine hotspots, 30% of all plants are endemics (in the Tropical Andes, an exceptional 6.7% are endemic) and 25% of vertebrate species are endemics; these hotspots account for 0.7% of Earth’s land surface (Table II). At the same time, they feature some of the most depleted habitats anywhere: Madagascar retains less than 10% of its original primary vegetation; Sundaland and Brazil’s Atlantic Forest less than 8%; the Mediterranean Basin, IndoBurma, and the Philippines less than 5%. Five hotspots hold more than 2% of the world’s biodiversity in both plants and vertebrates, hence they are super hotspots: Tropical Andes, 6.7% and 5.7%, respectively; Sunda-

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HOTSPOTS TABLE II

TABLE III

Leading Hotspots in Terms of Endemic Species

Species/Area Ratios per 100 km2 of Hotspots

Endemic plants (% of global plants total, 300,000)

Endemic vertebrates (% of global vertebrates total, 27,298)

20,000 (6.7) 15,000 (5.0) 9704 (3.2)

1567 (5.7) 701 (2.6) 771 (2.8)

8000 (2.7) 7000 (2.3)

567 (2.1) 779 (2.9)

Subtotal

59,704 (19.9)

4385 (16.1)

Mesoamerica Mediterranean Basin

5000 (1.7) 13,000 (4.3)

1159 (4.2) 235 (0.9)

7000 (2.3) 5832 (1.9)

528 (1.9) 519 (1.9)

90,536 (30.1)b

6826 (25.0)

Hotspot Tropical Andesa Sundalanda Madagascara Brazil’s Atlantic Foresta Caribbeana

Indo-Burma Philippines Total

a Hotspots with at least 2% of both endemic plants and vertebrates, and together comprising only 0.4% of Earth’s land surface (all nine hotspots amount to 0.7% of Earth’s land surface). b This would total 30.2% but for rounding of numbers in the individual hotspots.

land, 5.0% and 2.6%; Madagascar, 3.2% and 2.8%; Brazil’s Atlantic Forest, 2.7% and 2.1%; and the Caribbean, 2.3% and 2.9%. Collectively these five areas account for 20% of all endemic plant species and 16% of all endemic vertebrate species in just 0.4% of Earth’s land surface. They also harbor 45% of the plant and vertebrate endemics in the 25 identified hotspots.

B. Species/Area Relationships Some hotspots are also significant because their endemic species are concentrated in exceptionally small areas (Table III). The Eastern Arc and Coastal Forests of Tanzania/Kenya (hereafter referred to as ‘‘Eastern Arc’’) contain 1500 endemic plants in 2000 km2 for a ratio of 75 species to 100 km2, or 75 : 1, and 121 endemic vertebrates for a ratio of 6 : 1—both ratios top the lists for all hotspots. New Caledonia (5200 km2) has ratios of 49 : 1 and 1.6 : 1 for endemic plants and vertebrates, the Philippines (9023 km2) has 64.7 : 1 and 5.7 : 1, Polynesia/Micronesia (10,024 km2) has 33 : 1 and 2.2 : 1, and the Western Ghats in India (12,450 km2) has 17.5 : 1 and 2.9 : 1. Ratios for the other areas range from 18 : 1 to 1.2 : 1 for plants and from 2.9 : 1 to 0.03 : 1 for vertebrates.

Endemic plants

Endemic vertebrates

6.4 2.2

0.5 0.5

Caribbean Brazil’s Atlantic Forest Choco/Darien/Western Ecuador Brazil’s Cerrado

23.5 8.7 3.6 1.2

2.6 0.6 0.7 0.03

Central Chile California Floristic Province Madagascar Eastern Arc and Coastal Forests of Kenya/Tanzania

1.8 2.7 16.4 75.0

0.06 0.09 1.3 6.1

Guinean Forests of West Africa Cape Floristic Province Succulent Karoo Mediterranean Basin Caucasus

1.8 31.6 6.5 11.8 3.2

0.2 0.3 0.15 0.2 0.1

Sundaland Wallacea Philippines

12.0 2.9 64.7

0.6 1.0 5.7

Indo-Burma South-Central China Western Ghats/Sri Lanka

7.0 5.5 17.5

0.5 0.3 2.9

SW Australia New Caledonia

13.0 49.1

0.3 1.6

New Zealand Polynesia/Micronesia

3.1 33.3

0.2 2.2

Hotspot Tropical Andes Mesoamerica

C. Congruence among Species Categories In several hotspots, there is a measure of congruence between plants and vertebrates insofar as high counts for endemic plants are matched by moderately high counts for endemic vertebrates (Table IV). This factor can reinforce the conservation priority thesis, especially in those hotspots with the most endemic species. There can also be high congruence in areas with lower species counts, for example, there is 100% congruence in the Philippines with 1.9% of both endemic plants and vertebrate species worldwide, and 80% congruence in the Eastern Arc with 0.5% of plant species and 0.4% of vertebrate species. But the species percentages of these areas are low relative to those of several other hotspots. The Tropical Andes holds 6.7% of all endemic plant species worldwide and 5.7% of endemic vertebrates, for 85% congruence. Madagascar’s endemic species repre-

376

HOTSPOTS TABLE IV Congruence between Endemic Plants and Vertebrates Endemic plants as % of global plants total, 300,000

Endemic vertebrates as % of global vertebrates total, 27,298

% Congruence (rounded)

Tropical Andes Mesoamerica

6.7% 1.7%

5.7% 4.2%

85 41

Caribbean Brazil’s Atlantic Forest Choco/Darien/Western Ecuador Brazil’s Cerrado

2.3% 2.7% 0.8% 1.5%

2.9% 2.1% 1.5% 0.4%

79 78 53 27

Central Chile California Floristic Province Madagascar Eastern Arc and Coastal Forests of Kenya/Tanzania

0.5% 0.7% 3.2% 0.5%

0.2% 0.3% 2.8% 0.4%

40 43 88 80

Guinean Forests of West Africa Cape Floristic Province Succulent Karoo

0.8% 1.9% 0.6%

1.0% 0.2% 0.2%

80 11 33

Mediterranean Basin Caucasus Sundaland Wallacea Philippines

4.3% 0.5% 5.0% 0.5% 1.9%

0.9% 0.2% 2.6% 1.9% 1.9%

21 40 52 26 100

Indo-Burma South-Central China Western Ghats/Sri Lanka

2.3% 1.2% 0.7%

1.9% 0.7% 1.3%

83 58 54

SW Australia New Caledonia New Zealand

1.4% 0.9% 0.6%

0.4% 0.3% 0.5%

29 33 83

Polynesia/Micronesia

1.1%

0.8%

73

Hotspot

sent 3.2% and 2.8%, for 88% congruence; the Caribbean has 2.3% and 2.9%, to give 79% congruence. (The Tropical Andes is a large area where one could expect high congruence; the other two are only one-fifth and onetenth as big respectively.) By contrast, the Cape Floristic Province possesses 1.9% of all endemic plants but only 0.2% of all endemic vertebrates. Congruence tends to be high in tropical forest hotspots, and generally low in Mediterranean-type hotspots (the congruence for Cape Floristic Province is 11%) and other drier areas with their meager counts for endemic vertebrates. The four vertebrate groups reveal varying degrees of congruence among themselves. Birds and amphibians (like plants) generally show an increase in species numbers in the tropics and still more nearer the equator, with particularly high totals in tropical forests. Their numbers also increase with altitude up to 2500 m in

localities with good rainfall. Similarly, reptile abundance increases nearer the equator, though in drier zones it is comparable to that in tropical forests, as witness the situation in the two countries with the most reptiles, Australia and Mexico. Mammal numbers also increase closer to the equator, with drier areas again having a species richness comparable to that of tropical forests. Certain groups within the mammals, notably primates and bats, show similar trends to the birds and amphibians, though primates reveal their greatest species numbers in lowland rain forests, declining rapidly with altitude.

D. The ‘‘Hottest’’ Hotspots It is not practicable to devise a hotspots ranking index that combines five criteria, namely, numbers of endem-

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ics and endemic species/area ratios for both plants and vertebrates, and habitat loss. These criteria cannot carry equal weight (a case of comparing apples and oranges), so one cannot simply sum the rankings for each case. For comparative purposes, Table V lists the eight ‘‘hottest hotspots’’ that appear at least three times in the top ten rankings for each criterion. The leaders are Madagascar, the Philippines, and Sundaland, which appear in all five criteria, followed by the Caribbean and Brazil’s Atlantic Forest, which appear in four. Three of these hotspots (Madagascar, the Philippines, and the Caribbean) have small land areas, which further highlights their importance. Two additional hotspots, the Tropical Andes and Mediterranean Basin, should be considered as candidates for conservation support in light of their exceptional totals for endemic plants (Tropical Andes ranks highest for both endemic plants and vertebrates, and the Mediterranean ranks third for endemic plants). Yet they do not appear in Table V because they ranked in the top ten in only two criteria listings. Similarly, Mesoamerica ranks second for endemic vertebrates (49% higher than the third-ranking Caribbean), but scores only tenth for endemic plants.

bution of biodiversity overall. A top-down taxonomic approach, however, could compare the biodiversity of different areas using measures based on the number of higher taxa in each. For instance, family richness can often be a good predictor of species richness for certain groups and regions, including British ferns and butterflies, Australian passerine birds, and North and Central American bats, indicating that higher taxa indicators may sometimes offer a valid shortcut assessment. Madagascar possesses 11 endemic families and 310 endemic genera of plants, 5 endemic families and 14 endemic genera of primates, and 5 endemic families and 35 endemic genera of birds. The Cape Floristic Province has 6 endemic families and 198 endemic genera of plants; and New Caledonia has 5 endemic families and 112 endemic genera of plants, plus 1 endemic family and 3 endemic genera of birds. By contrast, the United States and Canada, with an area 8.8 times larger than that of the 25 hotspots combined, have only 2 endemic families of plants. Plant family richness can often serve as a predictor of species richness for certain animal groups, such as mammals, amphibians, and reptiles.

F. Action Responses

E. Higher Taxa Assessment Quantitative analysis can be complemented by a qualitative evaluation of endemism among higher taxa such as families and genera. Yet sufficient sampling and exhaustive surveys are not available to measure the distri-

To review, in just 1.4% of Earth’s land surface, there are 25 hotspots containing 44% of plant species and 35% of vertebrate species facing high risk of extinction. It is often estimated that, were the present mass extinction of species to proceed virtually unchecked, some-

TABLE V The Eight ‘‘Hottest’’ Hotspots in Terms of Five Factors (numbers in parentheses indicate the ranking in the top 10 hotspots for each factor)

Hotspot Madagascar Philippines Sundaland Caribbean Brazil’s Atlantic Forest

Endemic vertebrates

Endemic plants/ area ratio (species per 100 km2)

Endemic vertebrates/ area ratio (species per 100 km2)

Remaining primary vegetation as % of original extent

Times appearing in top 10 for each of five factors

9704 (4) 5832 (8)

771 (4) 518 (9)

16.4 (8) 64.7 (2)

1.3 (7) 5.7 (2)

9.9 (9) 3.0 (1)

5 5

15,000 (2) 7000 (6) 8000 (5)

701 (5) 779 (3) 567 (6)

12.0 (10) 23.5 (6) 8.7

0.6 (10) 2.6 (4) 0.6 (10)

7.8 (7) 11.3 7.5 (6)

5 4 4

75.0 (1)

6.1 (1)

6.7 (4)

3

0.5

4.9 (3)

3

2.9 (3)

6.8 (5)

3

Endemic plants

Eastern Arc and Coastal Forests of Kenya/ Tanzania Indo-Burma

1500

121

7000 (6)

528 (8)

Western Ghats/Sri Lanka

2180

355

7.0 17.5 (7)

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where between one-third and two-thirds of all species could be eliminated within the foreseeable future. The hotspots analysis indicates that much of this threat could be countered through protection of the 25 identified hotspots. An aggregate area of 800,767 km2, 38% of the hotspots total, is now protected in parks and reserves. Some of these are little better than ‘‘paper parks’’ in offering a modicum of legal status. All are in urgent need of stronger safeguards, including those five hotspots that fall entirely within protected areas. The areas without any protection at all amount to 1.3 million km2 or 62% of the hotspots total. In a few areas, new safeguards will not provide outright protection of a traditional sort because human settlements and other activities are well established. These areas could receive a measure of protection as ‘‘conservation units’’ that allow some degree of multiple use provided that species safeguards are always paramount. In short, the prospect of a mass extinction can be diminished and conservation efforts can be more effective by applying a hotspots strategy. The hotspots findings reported here complement several other priority-setting analyses. There is a 68% overlap with Birdlife International’s Endemic Bird Areas (Stattersfield et al., 1998), 82% with the World Conservation Union (IUCN)/World Wide Fund for Nature International Centres of Plant Diversity and Endemism (Davis et al., 1994–1997), and 92% with the most critical and endangered ecoregions of the World Wildlife Fund–US Global 200 List (Dinerstein et al., 1996). The hotspots approach is more comprehensive than the first two by combining five categories of species, and is more tightly focused than the third. There are surely other hotspots that feature exceptional plant endemism and face serious threat but that are not sufficiently documented to meet the hotspots criteria. They include the Ethiopian Highlands, the Angola Escarpment, southeastern China, Taiwan, and the forests of the Albertine Rift in eastern Democratic Republic of Congo (formerly Zaire), southwestern Uganda, and northern Rwanda. Were these five areas to be added to the hotspots list, they would increase the plants endemics total by only a few percent. In addition, there are a good many mini-hotspots. One such is Queensland’s Wet Tropics and adjacent tropical forest tracts along the Queensland coast, which contains a host of endemic species, with an exceptionally high species/area ratio (around 1200 endemic plants in less than 11,000 km2). To reiterate a key point: the biodiversity hotspots are not the only areas that deserve priority treatment from conservation planners. Indeed, every country has

its own biodiversity stocks, even if they are not as diverse or as concentrated as those of the major hotspots. We shall now look at three other criteria that warrant attention for conservation priority rankings.

V. WILDERNESS AREAS There are a few tropical forest expanses known as ‘‘major tropical wilderness areas’’ (Mittermeier et al., 1998) or ‘‘good news’’ areas (Myers, 1988, 1990) that total some 6–7 million km2 and feature concentrations of endemic species while retaining at least 75% of their primary vegetation. These areas also have fewer than five persons per square kilometer. One is the island of New Guinea, which has around 15,000 endemic plants. Others include the Guayana Shield of northeastern Amazonia, the lowlands of western Amazonia, and the Congolian Forest, with a total of perhaps another 30,000 endemic plants. Were these regions part of a supplementary conservation strategy, they could increase the endemic plants total to almost 60% of all plant species in roughly 5% of Earth’s land surface. Wilderness areas of all kinds, that is, not just biodiversity-rich areas, comprise nearly 90 million km2 of little-disturbed land, or well over half of Earth’s land expanse. But when areas of rock, ice, and otherwise barren land are excluded, nearly three-quarters of all habitable land has been disturbed to a significant extent. It is unlikely that most wilderness areas in question will be settled by large human communities within the foreseeable future because of unfavorable climate, difficult terrain, remoteness from markets, and other factors that mean they can be readily conserved in a wilderness state. Thus these areas merit priority treatment from conservation planners. There is still opportunity in these wilderness areas for conservationists to get things right—notably in terms of land use planning— from the very start.

VI. HIGH-VALUE ECOSYSTEMS Still another conservation strategy to be pursued in association with hotspots is to protect ecosystems of high value by reason of their exceptional abundance and concentrations of wildlife. These ecosystems contain large numbers of individual animals and large stocks of remarkable plants striking in appearance even though they comprise few species and few if any endemic species. A notable example is the Serengeti/Mara

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ecosystem in northern Tanzania and southern Kenya, which has 4 million wildebeest, zebras, gazelles, and other large herbivores in an area of only 25,000 km2 (all of these species are widespread elsewhere, though not in such extraordinary numbers). For comparison, the United States has roughly 20 million deer, moose, elk, pronghorn, caribou, and other large herbivores on 9 million km2. Other high-value ecosystems contain exceptional concentrations of endemic species, but only in a few categories. For instance, Lake Baikal has numerous endemic fish species but few species of other sorts, whether endemic or not, and Lakes Nakuru and Naivasha in Kenya possess exceptional numbers of bird species but few endemics, and has few other species of other types. Leading candidates among these high-value ecosystems include: • the Serengeti/Mara ecosystem; • the monarch butterfly overwinterning sites in Mexico; • the coastal Sundarbans area of India and Bangladesh, which has the largest tiger population left in the wild; • Lake Baikal, with 2000-plus fish species (15% of all freshwater fishes), 1500 of them endemic; • the East African Rift Valley lakes with 1200 fish species, 930 of which are endemic; • Lakes Nakuru and Naivasha, which have 400-plus bird species each, and a joint total of 600 (compare to the United States total of 770); Lake Nakuru usually has 250,000 flamingoes and occasionally 2 million; • the green turtle nesting grounds on Ascension Island in the Atlantic; • the caribou migration lands in Alaska; • the Galapagos Islands with their ‘‘museum of evolution’’; • the Great Barrier Reef with its outstanding coral reefs; and • the California, ecosystems that harbor giant redwoods and sequoias.

VII. MEGADIVERSITY COUNTRIES To effectively conserve a hotspot area, it is usually critical that the country’s government be committed to the conservation effort. As has been well said, hotspots do not have governments, only countries do. So a complementary approach to hotspot protection should focus on ‘‘megadiversity’’ countries. Such a country is defined

as one that either (a) contains 20,000 higher plant species or, in the case of a country with fewer than 20,000 but more than 10,000 such species, at least 5000 endemics; or (b) contains at least 2000 species of higher vertebrates (mammals and birds), or 200 such species as endemics. These 17 megadiversity countries encompass 60– 70% of all global biodiversity (Mittermeier and Mittermeier, 1997) (Table VI). When these countries are assessed for their rankings in terms of plants, vertebrates (including freshwater fish), butterflies, and tiger beetles, the top three countries are in a class of their own, namely, Brazil, Indonesia, and Colombia. They are followed by a second group that includes Mexico, Australia, Madagascar, and Peru, and then a third group of China, the Philippines, India, Ecuador, and Venezuela. Clearly there is need to give priority attention to these 17 megadiversity countries as well as to the hotspots— though in many instances, the two lists overlap.

VIII. THE CONSERVATION IMPACT OF HOTSPOTS The original hotspots strategy was first implemented in 1989 by the MacArthur Foundation with substantial funding for hotspots. Since then, over $400 million has been invested by international agencies and conservation groups. Yet this is only 0.8% of the total amount spent by governments during the same period on biodiversity conservation, (roughly $40 billion) and by international groups ($10 billion). These monies have been spent on across-the-board activities rather than the tightly targeted efforts advocated here. This $400 million is almost twice as much as the cost of the Pathfinder mission to Mars, which along with many other space probes has been justified largely on biodiversity grounds, namely, the search for extraterrestrial life. The hotspots could be adequately protected, and thus a large proportion of all species at risk, for just $20 million per hotspot per year (12.5 times the annual average over the past ten years). The traditional scattergun approach of much conservation activity, that is, seeking to be many things to many threatened species, needs to be complemented by a well-directed hotspots strategy that emphasizes the most cost-effective measures. Such a tightly targeted strategy could generate a handsome payoff in stemming the biotic holocaust that is now under way. In the 25 identified hotspots, 35% of Earth’s nonfish vertebrate species and 44%

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HOTSPOTS TABLE VI Megadiversity Countries: Plant Diversity and Endemism Area (km2)

Total species

Endemics

Brazil Indonesia

8,511,965 1,916,600

앑50,000–56,000 앑37,000

16,500–18,500 14,800–18,500

Colombia Mexico Australia Madagascar

1,141,748 1,972,544 7,686,810 587,045

45,000–51,000 18,000–30,000 15,638 11,000–12,000

15,000–17,000 10,000–15,000 14,458 8,800–9,600

China Philippines India Peru

9,561,000 300,780 3,287,782 1,285,210

27,100–30,000 8,000–12,000 ⬎17,000 18,000–20,000

Papua New Guinea Ecuador USA Venezuela

475,369 283,561 9,372,143 912,050

15,000–21,000 17,600–21,100 18,956 15,000–21,070

10,500–16,000 4,000–5,000 4,036 5,000–8,000

Malaysia South Africa Dem. Rep. Congo/Zaire

329,749 1,221,037 2,344,000

15,000 23,420 11,000

6,500–8,000 16,500 3,200

Country

Total

51,189,393

of plant species currently face unusually high risk of extinction. The hotspots analysis indicates that nearly half of the overall problem could be countered through protection of the 25 hotspots, covering an aggregate area the size of three Texases or one Mexico. In short, the likelihood of a mass extinction could be greatly reduced and made much more manageable. Leading players among the ‘‘global community’’ are international funding organizations (e.g., the World Bank and other multilateral banks, United Nations agencies, and bilateral aid agencies), international nongovernmental organizations (e.g., conservation bodies and private foundations), and business enterprises interested in biodiversity protection (e.g., pharmaceutical corporations). All of humanity has a stake in Earth’s biodiversity, and through a coordinated effort and directed actions we could make all contributions have maximum conservation impact. Recall that the mass extinction of species, if allowed to persist, would constitute a problem far graver than all other environmental problems. We could clean up acid rain, turn back deserts, and repair the ozone layer within a matter of decades, regrow forests and restore topsoil within a century or so, and even stabilize the global climate within a few centuries. But according to evidence from mass extinctions in

앑10,000 3,800–6,000 7,025–7,875 5,356

155,475–183,025

the prehistoric past, evolutionary processes are not likely to generate a replacement stock of species in less than 5 million years and possibly several times longer. Within the next few decades, we shall determine the future of a key feature of our biosphere, its abundance and diversity of species. The hotspots strategy offers a way to largely avoid an impoverishment of the Earth that could last at least 20 times longer than Homo sapiens has been a species. Obviously, a mass extinction will also affect a large number of people. Suppose the average global population during the 5-million-year recovery period is 2.5 billion rather than the 6 billion we have today, on the grounds that the world’s future ecosystems will be unable to support the current global population. This means that the total number of people who will be affected will be on the order of 500 trillion individuals. This figure dwarfs the 50 billion people who have existed so far. Even one trillion is a large number. To put it in perspective, consider the length of time made up of 1 trillion seconds. This, then, is the ultimate significance of the biotic holocaust that is overtaking the planet. Fortunately, we still have time to stem and slow the biodiversity crisis—and there are few ways to do it so successfully as by safeguarding the 25 hotspots that now harbor

HOTSPOTS

what nature has produced in its most exuberant expressions of life’s abundance and variety.

See Also the Following Articles BIOGEOGRAPHY, OVERVIEW • DIVERSITY, COMMUNITY/ GLOBAL LEVEL • ENDEMISM • INVERTEBRATES, TERRESTRIAL, OVERVIEW • SPECIES AREA RELATIONSHIPS • HUMAN EFFECTS ON ECOSYSTEMS, OVERVIEW • VERTEBRATES, OVERVIEW

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Mittermeier, R., and C. Mittermeier. (1997). Megadiversity: Earth’s Biologically Wealthiest Nations. CEMEX, Mexico City. Mittermeier, R. A., Myers, N., Gil, P. R., and Mittermeier, C. G. (1999). Hot spots: Earth’s biologically richest and most endangered terrestrial ecosystems. CEMEX, Monterrey, Mexico, and Conservation International, Washington D.C. Mittermeier, R. A., Myers, N., Thomsen, J. B., da Fonseca, YAB, and Oliveri, S. (1998). Biodiversity hotspots and major tropical wilderness areas: Approaches to setting conservation priorities. Conservation Biol. 12, 516–520. Myers, N. (1988). Threatened biotas: ‘‘Hot spots’’ in tropical forests. The Environmentalist 8(3), 187–208. Myers, N. (1990). The biodiversity challenge: Expanded hot-spots analysis. The Environmentalist 10(4), 243–256. Myers, N. (1993). Questions of mass extinction. Biodiversity and Conservation 2, 2–17. Myers, N., Mittermeier, R. A., Mittermeier, C. G., da Fonseca, Y. AB., and Kent, J. (2000). Biodiversity hotspots for conservation frontier. Nature 403, 853–858. Prance, G. T., Beent, J. H., Dransfield, J., and Johns, R. (2000). The tropical flora remains undercollected. Ann. Missouri Botanical Garden, in press. Stattersfield, A. J., Crosby, M. J., Long, A. J., and Wege, D. C. (1998). Endemic Bird Areas of the World. Birdlife International, Cambridge, United Kingdom. Wilson, E. O. (1992). The Diversity of Life. Belknap Press, Cambridge, Massachusetts.