and toucans, seeds may be dispersed several kilome-
ters. Within a fragmented landscape, occasional long-
distance dispersal may be critical for the maintenance
of isolated plant populations.
These results suggest that continuous forest should
extend down from the cloud forest to at least 1000 m
to maintain the dynamics and heterogeneous cli-
matic and topographic conditions that have produced
Monteverde's rich biological diversity. Increased for-
est cover and connectivity along the altitudinal gra-
dient will help maintain plants that are limited to
narrow microclimates along the gradient. Habitat cor-
ridors could facilitate the seasonal movements of spe-
cies such as quetzals and guans, thus increasing the
number of potential seed dispersers for large-seeded
bird-dispersed plant species, as well as movements
of vertebrates and invertebrates that adjust to seasonal
changes in resources or environments by moving up
and down altitudinal gradients.Table 12.1. Ten most common tree species occurring within forest fragments grouped by
altitudinal range.Frequency of Occurrence (stems/ha)SpeciesLower Middle Upper
(1000-1200m) (1200-1400m) (1400-1535m)
Inga punctata
Nectandra salicina
Sorocea trophoides
Dendropanax arboreus
Pseudolmedia mollis
Beilschmiedia sp.
Zanthoxylum fagara
Capparis pringlei
Styrax argentea
Cecropia obtusifolia
Matayba oppositifolia
Croton monteverdensis
Ocotea sp.
Ocotea floribunda
Beilschmiedia brenesii
Viburnum costaricanum
Pouteria exfoliate.
Mortoniodendron cf. guatemalense
Meliosma idiopoda
Stauranthus perforatus
Hasseltia floribunda
Eugenia guatemalensis
Ocotea white!
Chione sylvicola
Cecropia polyphlebia160
93
50
34
34
24
22
18
16
1657
32
28
3147
34
30
28
21
21 26
40
37
26
25
25
20
19
19
18
The sample area within each altitudinal range was 0.7 ha in 6 lower fragments, 2.6 ha in 12 middle
remnants, and 4.0 ha in 12 upper fragments.436 Conservation Biology