156
M.T.K. Arroyo et al.
rainforest in comparison to its to western North America analog (c.f. ,
Alaback, this volume) , with approximately equal numbers of ground
herbs. However, in South America, many ground herbs can be locally
distributed species, reflecting ecotonal effects. Alpine species commonly
invade the open canopy of high elevation Araucaria araucana forest and
well-lighted areas of deciduous Nothofagus antarctica and N. pumilio
forests (e.g., Adesmia exilis , A. retusa , Perezia pedicularidifolia, Ourisia
breviflora , Schi zeilema ranunculus , and Calceolaria biflora). Deciduous
Nothofagus forest also tends to contain more of the core rainforest herbs
than lower elevation forests. Veblen, Ashton, Schlegel, and Veblen (1978)
have related this last tendency to greater dominance of Chusquea in the
understory of low elevations forest. Other ecotonal effects are seen in the
sporadic appearence of Magellanic moorland species, such as Astelia
pumila, Oreobolus obtusangulus , Pinguicula antarctica, Gaimardia
australis , Donatia [asicularis, Drosera uniflora, Tapeinia pumila, Rostkovia
magellanica, and Tetroncium magellanicum in open-canopy Pilgerodendron
uviferum and Fitzroya cupressoides forests growing on poorly drained,
acid soils. If some of these species were disregarded, the nonfern, herbaceous flora would become considerably reduced in size.
Considering equal-size plots again (Figure 8.5) in Valdivian rainforest,
the number of herbaceous species in the understory can be very low.
However, it increases noticeably in far southern sites (Figure 8.5) again,
probably reflecting the smaller number of angiosperm trees forming a
shrubby stratum in the understory and the absence there of Chusquea .
In that rare herbaceous species occur under or within influence of the
canopy , however , they must be considered rainforest species. Some
common herbaceous species in rainforest are Acaena ovalifolia ,
Adenocaulon chilense , Calceolaria filicaulis , Chryso splenium valdivicum ,
Codonorchis lessoni, Dysopsis glechomoides , Fragaria chiloensis ,
Gunnera tinctoria , Iocenes acanthifolius , Lagenifera spp. , Leucheria spp .,
Nertera granadensis, Pilea spp., Rubus spp ., Senecio otites, Uncinia spp.,
Viola spp.
Finally , considering all life forms for an area about one half the size
(Weigand et aI., 1992), overall richness seems to be considerably higher
in the cool temperate rainforest of southern South America as compared
with North America (comparing our nonseasonal rainforest to data
supplied by P. Alaback, this volume). Perhaps more importantly, there
are striking differences in generic and familial diversity among the woody
and herbaceous members. From generic data supplied by P. Alaback,
the South American forest houses close to twice as many woody and
herbaceous genera, using again the comparison for nonseasonal rainforest.
South American cool temperate rainforest could also tum out to be
richer than Tasmanian rainforest, which has around 125 species of vascular
plants (Jarman et aI., 1991). However, given that the rainforest area in
Tasmania is about one tenth the size of that in southern South America, a
M.T.K. Arroyo et al.
rainforest in comparison to its to western North America analog (c.f. ,
Alaback, this volume) , with approximately equal numbers of ground
herbs. However, in South America, many ground herbs can be locally
distributed species, reflecting ecotonal effects. Alpine species commonly
invade the open canopy of high elevation Araucaria araucana forest and
well-lighted areas of deciduous Nothofagus antarctica and N. pumilio
forests (e.g., Adesmia exilis , A. retusa , Perezia pedicularidifolia, Ourisia
breviflora , Schi zeilema ranunculus , and Calceolaria biflora). Deciduous
Nothofagus forest also tends to contain more of the core rainforest herbs
than lower elevation forests. Veblen, Ashton, Schlegel, and Veblen (1978)
have related this last tendency to greater dominance of Chusquea in the
understory of low elevations forest. Other ecotonal effects are seen in the
sporadic appearence of Magellanic moorland species, such as Astelia
pumila, Oreobolus obtusangulus , Pinguicula antarctica, Gaimardia
australis , Donatia [asicularis, Drosera uniflora, Tapeinia pumila, Rostkovia
magellanica, and Tetroncium magellanicum in open-canopy Pilgerodendron
uviferum and Fitzroya cupressoides forests growing on poorly drained,
acid soils. If some of these species were disregarded, the nonfern, herbaceous flora would become considerably reduced in size.
Considering equal-size plots again (Figure 8.5) in Valdivian rainforest,
the number of herbaceous species in the understory can be very low.
However, it increases noticeably in far southern sites (Figure 8.5) again,
probably reflecting the smaller number of angiosperm trees forming a
shrubby stratum in the understory and the absence there of Chusquea .
In that rare herbaceous species occur under or within influence of the
canopy , however , they must be considered rainforest species. Some
common herbaceous species in rainforest are Acaena ovalifolia ,
Adenocaulon chilense , Calceolaria filicaulis , Chryso splenium valdivicum ,
Codonorchis lessoni, Dysopsis glechomoides , Fragaria chiloensis ,
Gunnera tinctoria , Iocenes acanthifolius , Lagenifera spp. , Leucheria spp .,
Nertera granadensis, Pilea spp., Rubus spp ., Senecio otites, Uncinia spp.,
Viola spp.
Finally , considering all life forms for an area about one half the size
(Weigand et aI., 1992), overall richness seems to be considerably higher
in the cool temperate rainforest of southern South America as compared
with North America (comparing our nonseasonal rainforest to data
supplied by P. Alaback, this volume). Perhaps more importantly, there
are striking differences in generic and familial diversity among the woody
and herbaceous members. From generic data supplied by P. Alaback,
the South American forest houses close to twice as many woody and
herbaceous genera, using again the comparison for nonseasonal rainforest.
South American cool temperate rainforest could also tum out to be
richer than Tasmanian rainforest, which has around 125 species of vascular
plants (Jarman et aI., 1991). However, given that the rainforest area in
Tasmania is about one tenth the size of that in southern South America, a