Fortuna Site Description
The 19,500 ha Fortuna forest reserve, located along the Continental Divide in Chiriqui, Western Panama, is managed by Fortuna SA for hydro-electric power generation. Details of the site are available on the Fortuna website (http://www.fortuna.com.pa/). The Fortuna reserve borders the Palo Seco Forest Reserve on the Caribbean slope of the Continental Divide in Bocas del Toro.
Although some groups of plants (e.g. Ericaceae, Arecaceae) have been extensively collected by specialists, and a provisional species list has been made for Fortuna (http://www.mobot.org/MOBOT/Research/fortunackl.shtml), plot based assessments of vegetation composition and structure have not been made for this site.
Here we provide brief descriptions of five sites within the Fortuna and Palo Seco Forest Reserves spanning the wet and dry sides of the Continental Divide and varying in soil fertility. Information on species composition come from identifications made in 1 ha plots that we are currently establishing at these sites.
Hornito Valley Forest
Rio Hornito Valley. Our sample plot is on the western slope of Cerro Hornito (right side of photo).
The forests of the western slope of the Rio Hornito valley (8 o40’26’’ N, 82 o12’51”W; 1250 m elevation) are among the drier sites within the Fortuna Reserve. Two tree species in the walnut family (Juglandaceae) are abundant at this site; on the ridges Alfaroacostaricensis, and on the slopes Oreomunneamexicanum. The canopy is 30-40 m high and includes large individuals of Cedrelatonduzii, Micropholis melinoniana, Pouteria sp., Ficus sp. and several species in the family lauraceae.
Canopy vegetation in the Hornito Valley.
Quebrada Samudio Forest
Canopy vegetation along Quebrada Samudio.
This site, along the Quebrada Samudio (8 o43’52’’ N, 82 o14’53”W; 1100 m elevation) is close to the STRI Fortuna Station and Fortuna SA’s Sitio de Presa. This is wet forest, with 30 m canopy height and a diverse tree community. Common tree species found at this site include Guareaglabra, Vochysiaguatemalensis, Hedyosmumbonplandianum and Cassipoureaelliptica. The understory is dominated by short-stature palms (Chamaedorea and Geonoma spp).
Quebrada Honda Forest
A view across the canopy of forest at Quebrada Honda.
This is a large patch of gently sloping forest northeast of the Fortuna dam ((8 o45’3’’ N, 82 o14’22”W; 1100 m elevation). Large patches of this forest are dominated by the canopy tree Oreomunneamexicanum, which can account for more than half the trees >10 cm stem diameter. The unusual passion-fruit tree, Passifloratica, and a tiny understory palm, Chamaedoreaverucunda, endemic to Fortuna, also occur at this site.
Interior of the Quebrada Honda forest. The large tree in the photo is Oreomunneamexicanum and can be identified by the large strips of bark that fall from the trunk and collect at the base of the tree.
Quebrada Chorro Forest
Colpothrinaxaphanopetala palms tower above the forest canopy at Q. Honda.
Quebrada Chorro crosses the highway a few hundred meters east of Q. Honda. This site, with a canopy of 20 m height, is dominated by the canopy palms Colpothrinaxaphanopetala, a species endemic to Panama, and Euterpeprecatoria. Large individuals of the gymnosperm tree, Podocarpusoleifolius is also abundant this site.
Interior of the Quebrada Chorro forest.
The abrupt shift in vegetation composition between Chorro and Honda is related to a change in soil conditions in this part of the reserve. The sub-soil here is composed of rhyolite, is very nutrient-poor, and is characteristically white.
White mineral soil of Quebrada Chorro.
Palo Seco Forest
The Palo Seco site is just across the Continental Divide from the Fortuna Reserve (8 o46’43’’ N, 82 o11’53”W; 900 m elevation). This site has a canopy of 30 m height and supports a very diverse community of canopy trees. Several palm species occur at this site but not in other plots, including canopy and sub-canopy species Socrateaexorrhiza, Cryosophila warscewiczii, and Iriarteadeltoidea. The understory is dominated by dwarf palms including Asterogynemartiana, Reinhardtiagracilis, and Chamaedoreatepejilote.