222
P.L. Meserve
make up only 9 of a total 27 species (see Table 10.2). However, it should
be noted that at least seven species recorded by Johnson et al. (1990) are
typical Patagonian steppe species. Elsewhere , there is almost complete
faunal turnover between temperate forest and Patagonian steppe small
mammals at lower latitudes (i.e., at ca. 41°S and 46°S latitude (Kelt,
1989; Pearson & Pearson, 1982). Virtually no Patagonian steppe species
penetrate the temperate forest region, and only a few widespread forest
elements occur on the steppe margins. Hence, the apparent "dilemma"
noted in southern Patagonia reflects a unique mixing of faunas in a region
where the two vegetational communities show a high degree of intergradation. Whereas 38% of the Patagonian fauna are of Valdivian and
Magellanic forest origin, 38% are primarily of Andean affinity, and 28%
are from the Patagonian steppes (Johnson et al., 1990).
As discussed earlier, historical and geographic factors may explain the
relatively depauperate and highly endemic character of terrestrial vertebrates in southern temperate rainforests. In addition, recent events
involving the large-scale extirpation of temperate forests in Chile may
also have had significant effects. Estimates of extant forest remaining in
Chile vary; Gilroy (1992), Hartwig (1991), and Schmidt & Lara (1985)
provide estimates of 6,250,000ha, 6,970,000ha, and 7,312,000ha, respectively, of extant forest remaining in Chile. However, estimates from GIS
yielded an estimate of the original area of 11,675,100 ha, with only about
25% left unlogged (Alaback in Kellogg, 1992) . Brun (1975; cited in
Veblen & Ashton , 1978) gave an estimate of 16% remaining in 1952. A
total of 5,447,903ha were listed by Veblen, Schlegel, & Oltremari (1983)
as being in national parks, monuments , or reserves; however, not all of
this is forest, much is in relatively inaccessible areas, and several large
reserves have since been removed from protected status by executive
decree .
At the northern end of the Chilean temperate forest region, MuiiozPedreros , Munia, & Gonzalez (1990) describe small mammal assemblages in exotic pine (Pinus radiata) plantations north of Concepcion,
where Mediterranean scrub and evergreen sclerophyll forests formerly
dominated. Although, as expected, small-mammal assemblages include
typical widespread species, such as A. olivaceus and O. longicaudatus,
and Mediterranean scrub/semiarid elements, such as Phyliotis darwini
and the marsupial Thylamys elegans, most notable is the importance of a
large octodontid rodent, Octodon bridgesi, heretofore considered rare
and uncommon in Chile (c.f., Redford & Eisenberg, 1992). In view of the
rapid rate at which native rainforest is disappearing in southern Chile, it
seems at least plausible that if pine plantations become progressively
more expansive in areas formerly dominated by temperate evergreen
forests, typical Mediterranean small-mammal elements will expand their
southern limits accordingly.
P.L. Meserve
make up only 9 of a total 27 species (see Table 10.2). However, it should
be noted that at least seven species recorded by Johnson et al. (1990) are
typical Patagonian steppe species. Elsewhere , there is almost complete
faunal turnover between temperate forest and Patagonian steppe small
mammals at lower latitudes (i.e., at ca. 41°S and 46°S latitude (Kelt,
1989; Pearson & Pearson, 1982). Virtually no Patagonian steppe species
penetrate the temperate forest region, and only a few widespread forest
elements occur on the steppe margins. Hence, the apparent "dilemma"
noted in southern Patagonia reflects a unique mixing of faunas in a region
where the two vegetational communities show a high degree of intergradation. Whereas 38% of the Patagonian fauna are of Valdivian and
Magellanic forest origin, 38% are primarily of Andean affinity, and 28%
are from the Patagonian steppes (Johnson et al., 1990).
As discussed earlier, historical and geographic factors may explain the
relatively depauperate and highly endemic character of terrestrial vertebrates in southern temperate rainforests. In addition, recent events
involving the large-scale extirpation of temperate forests in Chile may
also have had significant effects. Estimates of extant forest remaining in
Chile vary; Gilroy (1992), Hartwig (1991), and Schmidt & Lara (1985)
provide estimates of 6,250,000ha, 6,970,000ha, and 7,312,000ha, respectively, of extant forest remaining in Chile. However, estimates from GIS
yielded an estimate of the original area of 11,675,100 ha, with only about
25% left unlogged (Alaback in Kellogg, 1992) . Brun (1975; cited in
Veblen & Ashton , 1978) gave an estimate of 16% remaining in 1952. A
total of 5,447,903ha were listed by Veblen, Schlegel, & Oltremari (1983)
as being in national parks, monuments , or reserves; however, not all of
this is forest, much is in relatively inaccessible areas, and several large
reserves have since been removed from protected status by executive
decree .
At the northern end of the Chilean temperate forest region, MuiiozPedreros , Munia, & Gonzalez (1990) describe small mammal assemblages in exotic pine (Pinus radiata) plantations north of Concepcion,
where Mediterranean scrub and evergreen sclerophyll forests formerly
dominated. Although, as expected, small-mammal assemblages include
typical widespread species, such as A. olivaceus and O. longicaudatus,
and Mediterranean scrub/semiarid elements, such as Phyliotis darwini
and the marsupial Thylamys elegans, most notable is the importance of a
large octodontid rodent, Octodon bridgesi, heretofore considered rare
and uncommon in Chile (c.f., Redford & Eisenberg, 1992). In view of the
rapid rate at which native rainforest is disappearing in southern Chile, it
seems at least plausible that if pine plantations become progressively
more expansive in areas formerly dominated by temperate evergreen
forests, typical Mediterranean small-mammal elements will expand their
southern limits accordingly.