The Dry Forest of
“El Yunque” Group#1:
On the days of June 17 and July 5, we had
two separate field trips to two completely
different areas of Puerto Rico. We traveled to
the National Forest of “El Yunque” on June
17, then to Dry Forest of Guanica on July 5.
This experience gave us the opportunity to
make a comparison between these two
National Forest “El Yunque”
The name “El Yunque” comes from an Indian
Yunque means sacred or “Forest of Clouds”
because of its peek is covered by clouds.
It is the only Tropical Forest in the United
States National Forest System.
El Yunque is located at 40km southeast of San Juan
(latitude 18’19”W) in the rugged Sierra de Luquillo.
It is found on the East of the island and it covers
temperature is at
25.5 °C in the lowest
In the highest
reach up to18.5 °C
over 3,200 feet.
Most of the time it is
rainy. Annually, it
receives over 200
inches of rain.
The soil contains more than 50% of silica and
alumina, it is classified as clay soil.
El Yunque has around 240 species of native trees, in
which 26 are endemic species, 47 introduced
species and 88 are considered rare species.
It also has 50 different species of orchid and 150
The flora can be divided by height and can be
subdivided in 4 forests: The Tabonuco Forest or
Pluvial Forest, Palo Colorado Forest, Palma de Sierra
Forest and Dwarf Forest or Elfin Forest.
Tabonuco Forest or Pluvial
The lowest slopes of this forest has
a soil slightly good or moderated.
The trees in this part of the forest
can grow to measure 125 feet.
Some trees found are:
1. Tabonuco (Dacryodes excelsa)
2. Ausubo (Manilkara bidentata)
3. Yagrumo (Cecropia peltata)
4. Laurel sabino (Magnolia
Palo Colorado Forest
The Paolo Colorado Forest has a poor drainage soil.
The trees in this area of the forest can grow to be
100 years old. Some trees are:
1. Palo colorado (Cyrilla racemiflora)
2. Caimitillo (Micropholis garcinifolia)
3. Caimitillo verde (Micropholis garciniaefolia)
Palma de Sierra Forest
The most open forest of the four subdivision forest is
Palma de Sierra Forest.
Its ground or soil is superficial (not deep) and
1. Palma de Sierra (Prestoea montana)
Elfin Forest or Dwarf Forest
In this forest, the soil is acid and has poor drainage.
The vegetation receives strong winds and most of
the rain makes the trees grow no more than 12 feet.
The mist and clouds cover this area most of the time.
1. Roble de Sierra ( Tabebuia rigida)
Fauna or Wildlife
There are 120 different vertebrate species that
include amphibians and birds.
There are 11 different species of bats (mammals).
The most common invertebrates are snails and the
Puerto Rican Boa.
Puerto Rico’s most important native animal is the
“Coqui” (now an endangered specie).
Puerto Rican Boa
Has a dark brown
coloration. It grows to
about (6-9 feet) in
total length. It feeds
on small mammals
,birds, and lizards.
More than 16 different
species live in the
island, 13 of which occur
in the Caribbean National
Climate and Location
The Guánica Dry Forest zone covers most of our
It is located in the southwest coast of Puerto Rico
and covers Guánica, Guayanilla, Yauco, Peñuelas
It covers about 11,000 acres of land.
Climate and Location(continue)
The temperature varies from 24ºC – 28ºC with an
average of 25ºC, and with a maximum temperature of
Humidity varies between 65 to 80%.
The lack of rainfall, the high temperatures, the soils with
little accumulation of organic material and the
absence of permanent rivers make this ecosystem
Fauna or Wildlife
This ecosystem is home to both wildlife, marine and
land of great importance.
They have recorded 136 species of birds. 12 of
them are endemic (8 in the list of endangered
Furthermore, the forest contains a wide range of
insects that provide food for many birds.
On the marine fauna, there has been 150 species of
marine fish, 60 species of corals and 13 species of crabs
There has been a very valuable herpetofauna which
includes 21 species of reptiles and 6 species of
In Puerto Rico and The Virgin Islands there are 8 species
of endemic lizards .
The flora of the Guanica Dry Forest has adapted to very
There has been 550 species of plants found that can be
represented in 85 families. Nearly180 are native and
introduced trees. Around 19 are endemic.
45 of these species have been reported in danger by
In the Guánica Dry Forest, the flora modifies its
activities for the principal goal of all, to conserve
water. Some of the adaptations are: vertical
orientation of the leave to avoid direct
sunlight, stems that carry out the photosynthesis
and plants with thorn.
Most of the vegetation is semi deciduous (plants
that lose their foliage for a very short period).
Consequences of the
destruction of tropical forests
Throughout this century only we have lost
aporximately 50% of our forests and each
minute we loose 40 hectors more.
Protecting these forests is of extreme
importance for the continuity of the
biodiversity and because of their great
economical and social value.
Most importantly these forests regulate our
planet’s climates and maintain an ever
Victor Gonzalez Barahona has been in
charge throughout the years of
removing trees and terrain in forest
areas, with the excuse of positioning
energy providing wind mills. These wind
mills will supposedly provide energy for
a large amount of population but we
cannot sacrifice our forests for clean
energy. Removing these terrains will
negatively affect our natural integrity.
The newspaper El Vocero reported an
alert given by the Ornitologic Society of
The society was denouncing that “El
Monte Barinas” in Guayanilla is a dry
forest that was being misused and
deprived of 50 acres of terrain.
These acres were eliminated in order to
progress with the solar energy
proyect, “Estancias de Santa Rosa”.
About 200,000 trees were lost in the
process. These trees represented a
healthy continuity for this forest.
Also this forest is home to the “Concho
Frog” and the Guabairo, both species
in a very precarious state.
Benefits that the forests
A home for species that need to reproduce.
Control of the erosion and inundations.
An oportunity for recreation and exploration.
A Great diversity in species.
Consequences: The forests influence general
and local climate, they also moderate gama
rays, air tempedrature, the levels of
atmospheric humidity, absorb the carbon in
the atmosphere and replace the oxygen
needed in the atmosphere.
The field trips to El Yunque National Pluvial Forest and
the Guánica Dry Forest helped us compare the
differences between these two ecosystems.
According to our observations, we saw evidence of
the adaptations of plants on both forests. We can
also see evolutionary variation results from
disturbance of organisms in their environment. We
recommend to use the same measurement
equipment in both forests so the comparison
between them will be precise. In conclusion, these
trips enriched us with experience because they
allowed us to explore some of the natural resources
of our Island form a scientific perspective.