Tropical Forest Community Ecology

36 Paul V.A. Fineetal.

Table 3.1 Area and number of tree species for the 11 biomes included in the present study.

Biome Area

(in 1000 km^2 )

Estimated no.

of tree species

Sources

North American Boreal 5,117 61 Petrides and Petrides (1992),

Petrides (1998)

Eurasian Boreal 10,010 100 Hyttebornetal. (2005), A. Shvidenko

(personal communication)

North American Eastern

Temperate

3,396 300 Petrides (1998)

North American Western

Temperate

1,698 115 Petrides and Petrides (1992)

European Temperate 6,374 124 Latham and Ricklefs (1993)

East Asian Temperate 4,249 729 Latham and Ricklefs (1993)

South American

Temperate

413 84 Rodriguezetal. (1983)

Australian Temperate 735 310 Francis (1981)

Neotropics 9,220 22,500 R. Condit (personal communication),

R. Foster (personal communication)

Asian Tropics 5,903 14,000 R. Condit (personal communication),

J. LaFrankie (personal

communication)

African Tropics 3,471 6,500 R. Condit (personal communication)

Notes: Current biome area is estimated pre-human impact, and comes from the World Wildlife Fund (see map of biomes in

Olsonetal. 2001). Sources for estimated numbers of species per biome are listed in the table.

Woodward (2001). We synthesized these five
estimates to provide a “best guess” of tropical,
temperate, and boreal biomes for these particular
slices in time. These methods for estimating biome
ar ea through tim ear ecrud eand approximat e,
given the coarse temporal resolution of the under-
lying maps, the method used to calculate areas
ov er tim ein Figur e3.2, and th eunc ertainti es
associated with paleoclimatic reconstruction.
We traced biome boundaries based on
reconstructions of the Eocene (55 million
years ago [Ma]), Oligocene (30 Ma), Miocene
(11.5–5 Ma), Pliocene (3.5 Ma), Last Glacial
Maximum (21,000 years ago), and Mid-Holocene
(6000 years ago) onto equal area projections and
used ImageJ for Mac OSX to calculate the area of
each of the 11 biome areas at each time period.
For each biome area, geographic area size was
plott ed against tim e(Figur e3.2), th ear ea und er
each curve was traced, and this area estimated
using ImageJ. Then, these area–time measures
were log-transformed and tested for significance

by pairwise correlations with log-transformed cur-

rent tree diversity. This was performed for the area

und er th ecurv esinc eth eMioc en e, th eOligoc en e,

and th eEoc en e(Figur e3.2).

The extant species richness of biomes may also

be driven by extinction caused by contractions in

biome area during Pleistocene climate change. To

test this hypothesis, we correlated the minimum

size for each of the 11 biome areas at either the

Last Glacial Maximum or th eMid-Holoc en ewith

log current tree diversity.

EMPIRICAL TESTS OF THE GAH

AND GAAH

We found no significant relationship between cur-

rent biome area and tree diversity (R^2 =0.13,

P=0.3; Figur e3.3). Although tr ends ar e evi-

dent associating larger biomes with higher species

richness within the two boreal biomes, the three

tropical biomes, and the six temperate biomes,