Monteverde : Ecology and Conservation of a Tropical Cloud Forest

Table 9.4. Structural and floristic characteristics of seven tropical montane cloud forests.

Location

Luquillo Mountains,
Puerto Rico

Volcan Barva,
Costa Rica

Blue Mountains,
Jamaica
Papua New Guinea

Ecuador, Eastern
Andes

Monteverde,
Costa Rica

Forest

Type

"Colorado"

Lower

montane

wet

Lower

montane

rain

Mull ridge

Lower

montane

rain

Lower

montane

rain

Lower

montane

wet

Annual

Elevation Rainfall

(m) (mm)

725 3725

1500 3426

1550 3000

2500 3960

1710 nr

1480 2500

Plot

Size

(m*)

4000

10,000

1000 C

600 d

465 f

40,000

Tree

Density

(ha-^1 )

185 a

553 b

52 b

19 e

28 e

15078

396 h

1591

2062J

Basal Area

(mVha)

40

29.2

nr

98

nr

11,88

9.6h

52.4^1

73. 8J

Tree

Species

Richness

(sp./ha)

40

65

35

119

59 e

111

Source

Weaver and

Murphy 1990

Heaney and

Proctor 1990

Tanner 1977

Edwards

1977,

Edwards and

Grubb, 1977

Grubb et al.

1983

This chapter

aStems > 4 cm DBH.
bStems > 10 cm DBH.
cTen 10 x 10 m plots.
dThree 20 x 10 m plots.
eStems > 20 cm DBH.
fOne 61 x 7.6 m plot.
sStems 2-10 cm DBH.

also suggests disturbance is more frequent at Barva.

Thus, similar elevation and environmental conditions

do not necessarily dictate similar structure and floris-

tics in montane forests.

Forest dynamics. The frequency and types of loss of

tree crowns and the death of whole trees affect forest

regeneration, nutrient cycling, and species richness.

Relatively few studies exist for tropical lower mon-

tane forests. The rates and frequency of tree damage

might be expected to be greater in higher elevation

forests because of steeper slopes, less stable soil, and

exposure to more wind. Small-scale forest distur-

bances such as loss of crowns (herein "tree damage")

and treefalls are determined by local climatic forces,

physical characteristics of the substrate, and biologi-

cal attributes of the trees (Putz and Brokaw 1989).

When whole trees and their associated epiphytes fall

to the forest floor, they (1) present pulses of organic

material and nutrients that can subsequently become

available to terrestrially rooted plants (Denslow 1987);

(2) increase the biomass of the forest floor, which

creates additional habitats for terrestrial organisms;

3) reduce resources used by arboreal animals and epi-

phytes and create snags for nesting by key bird seed

dispersers (Wheelwright et al. 1984); (4) crush seed-

lings, saplings, and understory plants (Aide 1987);

and (5) affect microclimate of the ensuing gap, which

may subsequently deter or facilitate the germination

of seeds of some species (Putz and Milton 1982).

Although many damaged trees die, some continue

to live by producing new shoots from above- or below-

ground parts. Regeneration from broken plant seg-

ments ("resprouting") has been noted in some forest

trees (Clark and Clark 1989, R. Lawton, pers. comm.)

and shrubs (Kinsman 1990). Resprouting of damaged

individuals might replace lost substrate in the same

location and affect the form and duration of gap re-

generation faster than regeneration from seedlings.

Three censuses of marked trees in the leeward for-

est study area were made in September 1990, 1991,

and 1992 (Matelson et al. 1995). Tree damage and

mortality were divided into five categories: (1) stand-

ing broken stems, classified by the relative height of

the break (high, middle, low); (2) uproots (fallen trees

with exposed root wads); (3) knockdowns (trees fall-

ing as a result of a neighboring tree hitting them); (4)

standing dead trees (stems not broken or uprooted);

318 Ecosystem Ecology and Forest Dynamics