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.