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, 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
The forests of the western slope of the Rio Hornito valley (8o40'26'' N, 82o12'51"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 Alfaroa costaricensis, and on the slopes Oreomunnea mexicana. The canopy is 30-40 m high and includes large individuals of Cedrela tonduzii, Micropholis melinoniana, Pouteria jurana, Ficus sp. and several species in the family Lauraceae.
Quebrada Samudio Forest
This site, along the Quebrada Samudio (8o43'52'' N, 82o14'53"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 Guarea glabra, Vochysia guatemalensis, Hedyosmum bonplandianum and Cassipourea elliptica. The understory is dominated by short-stature palms (Chamaedorea and Geonoma spp).
Quebrada Honda Forest
This is a large patch of gently sloping forest northeast of the Fortuna dam (8o45'3'' N, 82o14'22"W; 1100 m elevation). Large patches of this forest are dominated by the canopy tree Oreomunnea mexicana, which can account for more than half the trees >10 cm stem diameter. The unusual passion-fruit tree, Passiflora tica, and a tiny understory palm, Chamaedorea verucunda, endemic to Fortuna, also occur at this site.
Quebrada Chorro Forest
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 Colpothrinax aphanopetala, a species endemic to Panama, and Euterpe precatoria. Large individuals of the gymnosperm tree, Podocarpus oleifolius, are also abundant this site.
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.
Palo Seco Forest
The Palo Seco site is just across the Continental Divide from the Fortuna Reserve (8o46'43'' N, 82o11'53"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 Socratea exorrhiza, Cryosophila warscewiczii, and Iriartea deltoidea. The understory is dominated by dwarf palms including Asterogyne martiana, Reinhardtia gracilis, and Chamaedorea tepejilote.
|Dept. of Plant Biology||School of Integrative Biology|
|Program in Ecology & Evolutionary Biology||University of Illinois|