low rates of evapotranspiration from the vegetation
(Sec. 2.6), and impeded drainage. Permanent puddles
1—4 m in diameter are common within these swampy
areas and are filled with up to 0.30-1 m of soft organic
material. These swampy areas are often occupied by
a distinctive vegetation dominated by Clusia sp.,
Didymopanax pittieri in the canopy, and Ardisia
solomonii in the understory. Larger swampy areas
occur on level ground at the windward foot of steep
slopes that receive high wind-driven cloud water and
precipitation inputs. A large accessible swamp is the
Pantano, a 0.75-km^2 area perched at 1600 m below the
peaks of Cerros Frio, Amigo, and Roble and skirted
by the Senderos Pantaiioso and El Valle of the MCFP
(Fig. 1.5). The surface of these swamps is speckled
with 2-5-m-diameter pools produced by the uproot-
ing of canopy trees. Because trees are shallowly
rooted, a root platform 0.15-0.3 m thick peels free
from the saturated underlying soil when uprooting
occurs. This leaves a depression filled with water over
deep, unconsolidated soil. Although these swamps
are forested, some small marshy openings in which
water flows as a 10—15-cm-thick sheet also occur, typi-
cally dominated by large, tussock-forming sedges.
Forest floor microtopography. The microtopography
of the forest floor is sculpted by biotic processes such
as treefalls and animal movement, and abiotic pro-
cesses such as the overland flow of water and erosion
of slopes. Small ledges or terraces normal to the di-
rection of maximum slope (terracettes) are conspicu-
ous in steeper areas. These are commonly incorpo-
rated into game trails; animal trampling plays a major
role in terracette formation (Carson and Kirkby 1972).
Debris trapping by tree trunks, surface roots, logs, and
tip-up mounds also contributes to the development
of these ledges. This microtopographic variation in
the forest floor accentuates variation in litter accumu-
lation and likely influences rates of decomposition
and nutrient release, with unknown but potentially
important consequences for the soil fauna and plant
establishment.
Springs and stream incision. Initial stream-channel in-
cision in soils derived from the Monteverde Forma-
tion is strongly influenced by soil structure. The A
horizon (Sec. 2.5) is typically porous and freely drain-
ing, but the underlying B and C horizons are less per-
meable. As a result, water readily infiltrates the A
horizon but moves laterally along the lower horizons.
This flow is concentrated in the depressions at the
head of primary watersheds and emerges as perma-
nent or intermittent springs at the A-B horizon bound-
ary at the head of incised stream channels ("knick-
points" sensu Dietrich et al. 1992), which are 2-3 mdeep at the point of origin. The flow at the A—B hori-
zon boundary often erodes a tunnel upslope from the
spring ("piping" sensu Dietrich et al. 1992). These
pipes may serve as part of the den system of pacas
(Agouti paca). Examples of springhead incision and
piping can be seen in the MCFP along portions of
the Sendero del Rio, Sendero Bosque Nuboso, and
Sendero Roble.
Upper ridgecrests in the relatively gentle terrain
derived from the Monteverde Formation are often
rounded. The size of these catchments varies in-
versely with cloud water and precipitation inputs
throughout the Cordillera. For example, in the very
wet region at the head of the Penas Blancas valley,
there may be only a 0.2 5-ha catchment upstream from
the point of stream channel incision; in the much
drier La Cruz—Alto Cebadilla region in the lee of
Cerro Chomogo, there may be a 1-10-ha catchment
above the point of stream incision.Landslides. Cliffs, waterfalls, quebradas, ridges, and
landslides are all ontogenetically related. Feeder
creeks typically plummet over valley headwalls via
waterfalls into quebradas. As fluvial erosion deepens
quebradas, the oversteepened side slopes eventually
become unstable and collapse. With continued ero-
sion, adjacent and parallel quebradas become sepa-
rated by ridges. The oversteepening of slopes due to
erosion, combined with buildup of a progressively
weaker superficial layer as weathering proceeds and
vegetation grows, leads to mass wasting by landslides
(Wentworth 1943, White 1949, Day 1980).
Landslides in Monteverde are often triggered by
torrential rains, which increase soil water potential
and decrease soil strength (Swanston 1970, Day 1980,
Crozier 1986, Jibson 1989). Earthquakes can also trig-
ger massive episodic landslides on a regional basis
(Simonett 1967, Garwood 1985). Magnitude 6.7 and
7.0 earthquakes off the Darien coast of Panama, for
example, triggered landslides covering 12% of a 450-
km^2 area (Garwood et al. 1979). Recent small earth-
quakes (magnitude < 5) in the Cordillera have not trig-
gered major landslides, but larger earthquakes have
occurred in this area, for example, magnitude 7 earth-
quakes that occur at approximately 25-yr intervals
(Marshall and Anderson 1995), so the opportunity for
catastrophic landslides in the Cordillera exists.
The spatial patterns of landslides in the physical
environment are important to forest structure, particu-
larly on the Caribbean slope where the abundance of
landslides can be seen from the Ventana pass in the
MCFP. The many small slumps (3-5 m across) that
typically involve rotational failure of creek banks do
not appear to influence forest structure, although they
contribute to the fluvial sediment load. In contrast,24 The Physical Environment