The bases for the high diversities among the different Mediterranean-type vegetations differ. In Israel, the diversity is accounted for mostly by herbaceous species, principally annuals, and is the result of human-driven “relatively rapid evolution under stress by drought, fire, grazing and cutting” (Naveh and Whittaker, 1979). In contrast, the high diversity of the South African fynbos (Mediterranean-climate scrubland) vegetation consists of woody species, of which there are few annuals. This type of vegetation has not been subject to a long history of human disturbance.

The data thus indicate that tropical systems are probably among the world’s richest in terms of local, or alpha, diversity, but that the vegetation of Mediter-

TABLE 17–1 Mean Numbers of Species per 0.1-Hectare Sample Area (Non-Mediterranean Sites Include Only Data for Woody Plants over 1 Inch in Diameter at Breast Height)

Sample Area

Mean No. of Species

Dry Tropical Foresta

 

Costa Rica upland, Guanacaste

41

Costa Rica riparian, Guanacaste

64

Venezuelan Llanos, Calabozo

41

Venezuelan coastal, Boca de Uchire

67

Moist Tropical Foresta

 

Panama Canal Zone, Curundu

88

Brazil, Manaus

91

Panama Canal Zone, Madden Forest

125

Wet Tropical Foresta

 

Panama Canal Zone, pipeline road

151

Ecuador, Rio Palenque

118

Costa Rica, near La Selvab

236

Temperate Zonea

 

Missouri, Babler State Park

21

Temperate Zonec

 

Australia, forests and woodlands

48

Tennessee, Great Smoky Mountains

25

Oregon, Siskiyou Mountains

26

Arizona, Santa Catalina Mountains

21

Colorado, Rocky Mountain National Park

32

Mediterranean Zoned

 

Israel, grazed woodlands

136

Israel, open shrubland

139

Israel, closed shrubland

35

California, grazed woodlands

64

California, closed shrubland

24

Chile, open shrubland

108

Australia, heath

65

South Africa, fynbos

75

aData from Gentry, 1979.

bData from Whitmore, 1986, for a 0.01-hectare plot.

cData from Whittaker, 1977.

dData from Naveh and Whittaker, 1979.



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