Ecology REBS

							ECOLOGY OF THE RESERVE
I. Introduction
      The Reserva Ecológica Bijagual de Sarapiquí (REBS) was established in March
2001 by a Costa Rican organization. It is operated by the Bijagual Center for
Environmental Education and Conservation (BCEEC), a Costa Rican and U.S. non-profit
organization.
      Located in the lowlands of northeastern Costa Rica in the Sarapiquí region, this
rainforest totals 225 hectares in area. About 155 hectares are forest that were selectively
logged. The remaining areas are abandoned pasture and secondary growth, of which
approximately 28 hectares have been reforested and 40 hectares are being left to
regenerate naturally.

Mission
The mission of REBS is to promote conservation and further the understanding of
tropical rain forests in the region of Sarapiquí by educating and aiding in training students
and local residents and by facilitating scientific research at the Reserve.
Goals
1. Protect biodiversity in the Reserve and support conservation of areas surrounding
Braulio Carrillo National Park.
2. Provide educational and training opportunities for local residents and Costa Rican
students at all academic levels.
3. Encourage research at the Reserve.

II. Geography/ Location
      The Reserve is located in the Distrito de La Virgen, Cantón de Sarapiquí, Provincia
de Heredia in the Republica de Costa Rica. REBS lies on the Río Cuarto Hoja 3347-II of
the Instituto Geográfico Nacional cartographic map. The Reserve lies between 300 - 450
meters above sea level. The town of La Virgen is 6.5 km due northwest of REBS; San
Ramón is 4.1 km to the southwest; Braulio Carrillo National Park lies 5.5 km to the east.
      The Administrative Building of REBS is located at 260.535 km North and 525.025
km East on the Lambert Projection Coordinate System or 10° 21‟ 46.8” North Latitude,
and 84° 6‟ 12.4” West Longitude. The elevation at the Administrative Building is 310 m
above sea level.

III. Topography
       The topography of the Reserve is very irregular and mainly dominated by steep
hills. Elevation ranges from 300 to 450 meters above sea level. Another feature of the
area is ridges that span approximately 200 to 400 meters in length

IV. Holdridge Life Zone
      The Reserve conforms to the classification of Tropical Wet Forest, premontane belt
transition according to the Holdridge Life Zone system. Tropical Wet Forest is described
as:
    “tall, multistratal, evergreen forest. A few canopy species are briefly deciduous, but
    this does not change the overall evergreen aspect of the forest. Canopy trees are 45-55
   m tall, with round to umbrella-shaped crowns, and have clear boles to 30 m and
   attaining 100-200 cm dbh. Smooth, thin, light-colored bark and high buttresses are
   common. Subcanopy trees are 30-40m tall, with round crowns and slender trunks,
   generally lacking buttresses. Understory trees are 10-25 m tall, with narrow conical
   crowns and slender boles, often twisted or crooked, usually with smooth, dark bark,
   occasionally cauliflorous. Stilt-rooted palms are often abundant. Shrub layer is 1.5-
   2.5 m tall with abundant dwarf palms; unbranched treelets and giant broad-leaved
   herbs are occasional. The ground layer is sparse, with a few ferns and Selaginella.
   Woody lianas are not common, and epiphytic shrubs and strangling trees are rare.
   Tropical Wet Forest is the most species-rich Life Zone in Costa Rica.” (Janzen 1983)

V. Climate
A. Rainfall
      Data from the Reserve collected between February 2002 and December 2004
indicate that average annual rainfall is 5500 mm. To date, the wettest month is May 2004
(1124.2 mm) and the driest month March 2003 (63.7 mm).

B. Temperature
     The mean minimum temperature is 20°C and the mean maximum temperature
33°C. Lowest temperature was during the month of May 2002 (15°C) and highest June
and September 2004 (40°C).

C. Meteorological Station
      A weather station was installed in February, 2002 using an All-Weather Rain Gage
and a Dual Scale Maximum-Minimum Thermometer from Forestry Suppliers. The station
is located in the Arboretum—in an open, flat, abandoned pastureland at approximately 40
meters along Sendero La Puerta.
      Data is collected daily and is available on the Reserve‟s web page. Annual
summaries in graphic form are also posted on the web page.

VI. Hydrology
A. Rivers
      REBS lies within the Sarapiquí River watershed, an area which covers 1923 km2
(Bergoeing, 1998). The Sarapiquí divides the piedmonts of the Poás and Barva volcanoes
and flows north from its headwaters near Vara Blanca. The river turns east briefly
between the Bajos of Chilamate and Puerto Viejo before returning to flow north and
emptying into the San Juan River in Trinidad, Costa Rica.
      Two rivers (a total of 3200 meters) flow through REBS. The Bijagual forms the 1.7
km eastern border and includes the Catarata Bijagual. Its headwaters occur around 1000
m above sea level about 8 km south of the Reserve. The smaller Tirimbina River passes
for about 1.5 km through the western side of REBS and contains two falls, Tirimbina
Norte and Tirimbina Sur. The Tirimbina arises at about 700 m above sea level, 6 km
south of REBS. The Tirimbina and Bijagual empty into the Río Sarapiquí.

B. Streams
      There are 14 streams (a total of 6835 meters) running through the Reserve, ten of
which originate within the Reserve. Most are constantly flowing, clear water streams
although very few are considered intermittent or ephemeral. Rivers and streams flow
from south to north. They are located predominantly in forest with few running through
abandoned pasturelands and reforestation areas. At the northern section of the Reserve,
rivers and streams are more sedimented. Upstream, they are characterized by faster
moving waters, big boulders, and stones.

C. Ponds and Swamps
1. Ponds
      There are three ponds within the Reserve, two natural and the other artificially
created by a dam. The larger natural pond is oval shaped, approximately 30 meters by 50
meters (1500 m2). It is located near the source of Quebrada Agami about 100 meters from
the road. The second natural pond is approximately 20 meters wide by 50 meters long
(1000 m2), located near the intersection of Río Tirimbina and Trocha Principal along the
forest edge. Approximately a meter or more in depth, the water flows slowly and is more
or less transparent. The artificial pond is 10 meters wide by 15 meters long (150 m2),
located at the intersection of Quebrada Prestoea and Sendero Manakin along the forest
edge. Furthermore, one of the most striking characteristics is the dark, murky water filled
with sediment.
2. Swamps
      Two swamps have been encountered within the Reserve. The larger swamp is
located along the Quebrada Prestoea where the Trocha Chancho intersects in the
reforestation area. It extends approximately 200 meters downstream with a width of 60
meters (12,000 m2). It is an almost empty area dominated by grasses, aroids, sedges, and
few trees. A second smaller swamp is located where Quebrada Prestoea and Trocha
Principal intersect. It has the same vegetation characteristics as the larger swamp but with
dimensions of 40 meters by 40 meters (160 m2).

VII. Land Use History
A. Managed Forest [125 ha]
Between 1971/1975 timber trees were selectively logged by the previous owner
throughout this area of the Reserve. The list of tree species extracted include: Lecythis
ampla, Cedrela odorata, Pentaclethra macroloba, Hieronyma alchorneoides, Vochysia
ferruginea, Terminalia amazonia, Minquartia guianensis, Aspidosperma spruceanum,
and Dalbergia melanocardium. The understory remains intact with about 25 species of
palms, several Psychotria species and Zamia. Old tracts about 3 m wide where tractors
removed the timber are present in this area with the majority maintained as trails. The
area of Managed Forest is included in the 131.5 has which have been designated for
protection under the FONAFIFO-MINAE Payment for Environmental Services (PSA)
programs in the category of Protection of Forest. At least 16 rivers and streams and 11
springs are found in this forest.

B. Old Growth Forest [6.5 ha]
Because of the location and difficult access to this area, no trees were logged in this part
of the Reserve. Large trees are found in this old growth forest including Lecythis ampla
and understory palms. This entire area comprises part of the 131.5 ha that have been
designated for PSA protection.

C. Reforestation Areas [28.3 ha]
There are five distinct areas of reforestation within the Reserve:
1) RF1 is a 0.7 ha area planted by Reiner Vargas Arce with Cordia alliodora.
2) RF2 is a 2.8 ha stand mainly along the slope on the western side of the Río Bijagual.
There are three stands of tree species, Vochysia guatemalensis, Terminalia amazonia, and
Gmelina arborea (an exotic species) planted by Noe Perez in 1992. The understory has
not been disturbed for many years.
3) RF3 is an area of 0.5 ha planted with Vochysia guatemalensis in a remnant secondary
forest along the river.
4) RF4 is a 2.5 ha internal biological corridor connecting the western Managed Forest
with the eastern riparian forest along the Río Bijagual. This area was planted in January
2002. There are nine native tree species planted here: Vochysia guatemalensis, Cordia
bicolor, Vitex cooperi, Terminalia amazonia, Simarouba amara, Minquartia guianensis,
Otoba novogranatensis, Hieronyma alchorneoides, and Xanthoxylum panamensis. At the
first replanting, the following species were planted: Pourouma aspera and Inga spp.
5) RF5 is a 25 ha plantation of seven native tree species, Hieronyma alchorneoides,
Vochysia guatemalensis, Terminalia amazonia, Tabebuia guayacan, Tabebuia rosea,
Calophyllum brasiliense, and Virola koschnyi. This area planted in August 2002 is also
part of the governmental program (PSA) under the category of Reforestation.

D. Secondary Forest [2.4 hectares]
This small area is located mainly along a slope between two hills. Plant species found
here include Hampea appeniculata, Ochroma pyramidale, and Casearia arobrea. This
area was active pastureland before regenerating into forest.

E. Regenerating Pastures [25.8 hectares]
These areas are being left to regenerate naturally.
1) PR1 is an area of 0.7 ha abandoned in June 2001.
2) PR2 is an area of 8.6 ha abandoned in June 2002.
3) PR3 is an area of 16.5 ha of pastures which were totally cleared and were grazed by
cows until September 2002.

F. Active Pastures [2 hectares]
In these areas, 1-3 cows or horses are currently allowed to graze

G. Administration Area (AA) [1 hectare]
These clearings are areas surrounding buildings that are cleaned monthly.

H. Arboretum [1.5 hectares]
Pasture abandoned in June 2001 is being planted with two individuals of each tree species
found at REBS to establish an arboretum.

VIII. Archeology
Reiner Vargas Arce found two sites with petroglyphs engraved on boulders at two
locations along the Río Tirimbina, along the bank (Figure 11a) and beside Catarata Sur
(Figure 11b). He also found „metates‟ and pot shards. In September 2002, Felipe Sol, an
archeologist from the Museo Nacional de Costa Rica, visited these sites and confirmed
their authenticity, estimating their origin as 500-1000 A.D. He interpreted the drawings
as a reflection of housing structures and ceremonial sites. Currently, he is in the process
of trying to link this information with other sites in the region.

VI. Trails
      The 16.8 km trail network provides access to the Reserve. 52% of the trails take
advantage of existing logging tracks created by the previous owner to extract trees. The
logging roads were used in order to minimize erosion. Trails were chosen based on an
existing map of the logging tracks and exploration of the forest considering habitats,
topography and interesting features. There are 23 trails named after an interesting feature
that characterizes the area along each trail.
      Trails start in the Administrative area with a sign indicating name, three-letter
abbreviation and length. All trails are marked at 50 meter intervals with ¾” PVC conduit
1.5 meters in length. Each pipe is labeled with a white tag indicating the name of the trail
with a three letter abbreviation and the distance along the trail. At trail intersections, signs
parallel to the trail indicate that trail‟s name.
      The width of trails is approximately 1 meter to 2 meters. Trails closest to the Casa
Administrativa have been improved with cuts, steps and drainage ditches. However, most
remain cleared without major improvements.