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Distribution of Epiphytic Diversity in a Costa Rican Premontane
Tropical Rainforest
O. Santiago1, D. Spalink2, G. Moore2, K. Brumbelow3
1University of South Florida, Dept. of Integrative Biology; 2Texas A&M University, Dept. of Ecosytem Service Science and Management; 3Texas A&M University, Dept. of Civil Engineering
Acknowledgements:Funding for this Research Experiences for Undergraduate program is provided by
the National Science Foundation’s Division of Earth Sciences (EAR-1659848).
Thank you to the Soltis Center de Peñas Blancas for Research and Education, the
REU 2019 cohort, and M.E. Devinney for their support of this research.
Introduction
Conclusion
MethodsResults
Microclimates formed by abiotic
conditions such as temperature,
precipitation, humidity, and soil
conditions change sharply with
changing altitude, providing the ideal
settings to study effects of species
richness and distribution across small
spatial scales1.
The community composition of
vascular holo-epiphytes was
assessed along elevational gradients
using a visual ground survey in
June and July 2019. Sampling was
restricted to primary forests within
the Soltis Center de Peñas Blancas
and the Pocosol Field Station of the
Children’s Eternal Rainforest. Three
replicates were used respectively
at four elevations (400 m, 600 m,
800 m, and 1000 m) for a total of
twelve sampling sites. A total of
2996 epiphytes were sampled,
representing four families, twelve
genera, and 110 morphospecies.
Hypothesis
References:1. Rosenberg, Norman J., Blaine L. Blad, and Shashi B.
Verma. Microclimate: the biological environment. John Wiley &
Sons, 1983.
2. Jost, Lou. "Entropy and diversity." Oikos 113.2 (2006): 363-375.
3. Masisi, L., V. Nelwamondo, and Tshilidzi Marwala. "The use of
entropy to measure structural diversity." 2008 IEEE International
Conference on Computational Cybernetics. IEEE, 2008.
Epiphytes will be non-randomly
distributed along elevational gradients
due to adaptation to microclimates.
ObjectiveOur aim was to survey vascular holo-
epiphytes in a Costa Rican premontane
rainforest to assess ꞵ-diversity,
species richness, and abundance of
epiphytes along an elevational gradient.
Table 1. PS index measures the species overlap of one area to another. The AST measures the amount
of species found exclusively in one area when compared with another. The matrices revealed low
overlap from one elevation to another, with the exception of 600 meter sites to 800 meter sites.
Figure 1. The species distribution at 400 meter sites was the most even, followed by 1000 meter
sites, 800 meter sites, and 600 meter sites, which was the least even. Each elevational was
dominated by a particular species, as listed in the graph above.
Table 2. β diversity values closer to one indicate that a site has greater proportion of the total regional
diversity, whereas larger values indicate that a site has a lower proportion of the regional diversity. These
calculations revealed the 1000 meter sites may be the most limiting, with relatively the smallest
component of diversity being observed, while the 400 meter sites may be the least limiting, with
relatively the largest diversity being observed.
Our preliminary evidence provides
support for our hypothesis that
epiphytes are non-randomly
distributed along elevation gradients.
In the future, we seek to explore niche
specificity and endemism of epiphytes,
which could have implications for
distribution shifts and potential extinction
amidst climate change.
Results Continued
0
0.02
0.04
0.06
0.08
0.1
0.12
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49
400 m
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29
600 m
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41
800 m
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
1 3 5 7 9 11 13 15 17 19 21 23 25 27
1000 m
Percent Similarity Index (PS) for Each Elevation
Elevation (m) 400 600 800 1000
400 1 0.25 0.27 0.11
600 1 0.60 0.11
800 1 0.18
1000 1Absolute Species Turnover (AST) for Each Elevation
Elevation (m) 400 600 800 1000
400 65 69 22
600 54 49
800 51
Pictured above: Olivia (left) in the canopy tower at the
Soltis Center in San Isidro de Penas Blancas, Costa
Rica inventorying the epiphytes found on a large tree
(right).
Ele (m) α-Div γ-Div β-Div
400 50 110 2.20
600 29 110 3.79
800 41 110 2.68
1000 28 110 3.93
Table 1. Percent similarity index and absolute species turnover matrices. Eq 1. PS = Σ(% minimum of
species common to both sites). Eq 2. AST = (S1-c) + (S2-c). S1 = species richness in area 1, S2 = species
richness in area 2, c = species common in both areas. A total of 2996 individuals were sampled over all
elevations, with 576, 608, 960, and 852 individuals at each respective elevation below.
Figure 1. Relative abundance of morphospecies at each respective elevation. Morphospecies (x-axis).
Relative abundance (y-axis) where relative abundance = ( Τcount of species A) (total count of all species). Table 2. Shannon Weiner Diversity Index
(H) and β-Diversity of Epiphyte Distribution
along Elevation Gradients.
Eq 3. β diversity=γ diversityα diversity
• Eq 3. follows Whittaker’s multiplicative law.
• γ diversity – species richness in region
• α diversity – species richness in site
• β diversity – difference in species
compositon across sites
Campyloneurum phyllitidis, 10.59% Campyloneurum falciodeum, 40.95%
Campyloneurum falciodeum, 34.58% “Pointy leaf bromeliad”, 18.66%
Pictured left is a
typical dominant tree
at the Soltis Center,
featuring vines,
epiphytes, and the
canopy. Photo credit
to Dr. Brumbelow.