The New Neotropical Companion

Unique and Endangered Polylepis

Woods

At elevations between 3,500 and 4,500 m (11,480–

14,760 ft) in the Andes, above timberline, islands of

gnarled trees dominated by the genus Polylepis (about

20 species, family Rosaceae) are found scattered in

a landscape of wet páramo (see below for more on

páramo). Polylepis trees are typical of wind- protected,

rocky slopes (plate 13- 24). Though Polylepis can be

found mixed among other species in lower- elevation

cloud forests, the genus occurs in pure stands at higher

elevations. Polylepis is evergreen, its leaves drought

resistant. The largest trees reach heights of about 18 m

(60 ft), but most are of smaller stature. Studies in central

Ecuador have shown that seedlings survive best when

deep within the Polylepis stand, where wind conditions

are far less severe. However, vegetative propagation by

shoots and ramets (a ramet is a stem that arises from

an underground root), a form of asexual reproduction,

is highest at the boundary of the woodland. This

suggests that with protection, stands of Polylepis could

increase in area. Several specialized bird species are

found in Polylepis woods, including the Giant Conebill

(Oreomanes fraseri; plate 13- 25). Conebills belong to

the huge tanager family (Thraupidae), and most occur

at lower elevations. This species is unique to Polylepis

woods, occurring at 3,500– 4,200 m (11,480– 13,780 ft)

in Ecuador, Peru, and Bolivia.

Though Polylepis woodlands range from Venezuela

to northern Argentina and Chile, this ecosystem type

has been much reduced by cutting and is threatened

throughout most of its range.

Cold, Windy, Wet, Wonderful Páramo

Páramo is a shrub and grass ecosystem occurring from

Costa Rica south to Bolivia at elevations above those

that support cloud and elfin forest, generally above 3,800

m (12,470 ft). The climate is wet and cool (often cold),

and nightly frosts are frequent throughout the year.

Approximately 5,000 plant species, including numerous

endemic species, are known from páramo ecosystems,

which are characterized by large areas of wet grass often

interrupted by peat bogs. Dominant vegetation consists

of large, clumped tussock grasses, which have sharp,

yellowish blades, along with a scattering of terrestrial

bromeliads and ferns (plate 13- 26). Shrubs, most in the

genus Espeletia, grow among the tussock grasses, some

reaching heights of 4– 5 m (approx. 13– 16.5 ft), so they

resemble small trees. Leaves grow from the base of the

stem, surrounding it in a pattern termed a rosette. A

number of bird species make their home in páramo; two

are shown in plates 13- 27– 28.

Espeletias are some of the oddest- appearing members of

the immense sunflower or composite family (Asteraceae

or Compositae), to which daisies, asters, and goldenrods

belong. Espeletias have short, thickly woolly trunks

densely surrounded by withered dead leaves and topped

by a rosette of thick, elongate green leaves, each covered by

soft hairs that help minimize evaporative water and heat

loss (plates 13- 29– 30). Espeletias are indicator species

of South American páramo. (Similar high- elevation

ecosystems in Central America lack espeletias.) Scattered

among the tussock grasses on the cold, windy Andean

slopes, espeletias attract many hummingbirds and bees to

feed on the nectar of their yellow flowers.

Plate 13- 29. Espeletia dominates the landscape high in the

Venezuelan Andes. Photo by John Kricher.

Plate 13- 30. Espeletia in flower. Note the thick leaves. Photo by

Bruce Hallett.

chapter 13 scaling the andes 247