Monteverde : Ecology and Conservation of a Tropical Cloud Forest

had similar amounts (12% and 15%, respectively);
reproductive parts, stems, ferns, and epiphytic foli-
age made up a very small proportion (Table 9.7).
Inner branch mats of EM were dominated by organic
matter, which occurred in four forms: DOM, foliage,
roots, and bryophytes. Roots made up approximately
15% of the inner branch mats; around 30% of them
were fine roots (<2 mm). Branch junction EM con
tained primarily humus and roots. Fine roots com-
prised a larger proportion of the total root biomass
in the branch junctions (45%) than on the mats on
branch surfaces (Vance and Nadkarni 1992). Bryo-
phytes predominated on branch tips, understory
vegetation, and on groundcover (Table 9.7).

Comparison of canopy and forest floor organic matter.
The pH of dead organic matter in the canopy and at
two levels of the forest floor differed strikingly. There
was a significant difference in percentages of carbon
and nitrogen between canopy EM and forest floor
humus horizon (0-10 cm deep; Table 9.2). Canopy

EM was higher in nitrogen. All types of organic mat-

ter had a similar C:N ratio. Our results are comparable

to the few published values of nutrient content and

characteristics from other studies in tropical forests

(Edwards 1977, Tanner 1980b, Putz and Holbrook

1989). They are slightly lower in nitrogen, carbon, and

exchangeable bases than those reported for organic

soils of Colombia (Lopez and Cortes 1978).

Roots. Biomass and nutrient pools of roots are two

of the great unknowns in the study of forest produc-

tivity and nutrient cycling, due to the difficulty in

excavating root samples at depth (Vitousek and San-

ford 1986). In the leeward cloud forest study area, we

studied soil characteristics and fine and coarse root

biomass in the soil and in the canopy (Vance and

Nadkarni 1992). The canopy provides a second habi-

tat for roots as functional absorptive organs that could

be potentially important in ecosystem functioning.

Canopy roots can be derived from vascular epiphytes

growing in the canopy, from the host tree themselves

322 Ecosystem Ecology and Forest Dynamics

Table 9.6. Aboveground biomass (tons/ha) and nutrient

contained in terrestrially rooted and epiphytic material

Cloud Forest Preserve leeward cloud forest study area.

Biomass

Terrestrially rooted material

Trunk wood

Branch wood

Sapling wood

Groundcover

Tree foliage

Reproductive Parts

Parasites

Total

Nonwoody

Epiphytic material

On trunks

Branch junctions

Branch mats

Inner branches

Branch tips

Sapling cover

Ground cover

Total

Total ecosystem

% Epiphytic/total

% Epiphytic/nonwoody terrestrial

418.8

60.0

2.0

2.4

6.5

0.2

0.2

490.1

9.3

3.0

22.4

6.2

1.1

0.2

0.1

0.02

33.1

523.2

6.3

360

N

2847.8

624.0

37.8

68.9

149.5

4.1

2.3

3734.1

224.8

41.9

305.0

72.1

13.8

2.6

2.7

0.5

438.7

4172.8

10.5

190

P

167.5

42.0

2.2

2.9

7.1

0.5

0.2

222.4

10.7

2.2

13.5

4.4

0.7

0.2

0.1

0.05

21.1

243.5

8.7

200

capital (kg/ha)

in the Monteverde

Ca

2931.6

702.0

17.0

30.9

63.1

1.2

1.4

3747.2

96.6

35.9

112.0

36.7

6.2

0.9

1.6

0.4

193.7

3940.9

4.9

200

K

3476.0

372.0

21.0

55.3

69.6

2.9

1.1

3997.9

128.9

23.0

76.9

44.3

5.2

1.4

0.7

0.5

152.0

4149.9

3.7

120

Mg

879.5

84.0

4.2

8.7

19.5

0.4

0.3

996.6

28.9

3.9

25.8

11.2

1.6

0.3

0.2

0.1

43.1

1039.4

4.2

150

Total for each category indicates all components; nonwoody terrestrial material is foliage, reproductive

parts, herbaceous vegetation, and parasitic plants. Percentages of epiphytic material as part of the forest

are calculated as (1) the proportion of epiphytic material to the total aboveground ecosystem (terrestri-

ally rooted + epiphytic totals) and (2) the proportion of epiphytic material to nonwoody terrestrially rooted

components.