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BCI Survey Area

Location and access

BCI is in the Gatun Lake, at the northwestern (Caribbean) end of the Panama Canal, in the central part of the Republic of Panama, Central America, at latitude 9º 08’ – 9º 11’ N, and longitude 79º 49’ – 79º 52’ W. Access is easy, about 0.5 – 1 hour by boat from Gamboa, which is about 25 km by blacktopped road from Panama City.

Barro Colorado Island

The shape of the 1571 ha island resembles a compact star, with original spurs forming the current peninsulae and valley heads forming the bays. It stretches about 6 km N-S and E-W. There are 41 km of well-maintained foot trails. The laboratory/residential complex is on the northeastern coast. All points on the trail system can be reached in < 1.5 hours walk from the lab, and there is nowhere on the island that is more than 1.2 km from a trail. Less accessible areas can also be reached by boat to the nearest shore and then inland on foot.

Barro Colorado Island

Climate

There are summaries of the climate of BCI in Leigh (1999) and Leigh et al. (1996). Important features for soil development and correlation include:

  • Warm temperatures, with an annual mean of about 27º C, and an annual range of monthly means of less than 2º C; and diurnal ranges of about 8 – 10º C.
  • Mean annual rainfall of about 2600 mm, with a strongly seasonal distribution. Monthly rainfall averages less than 60 mm for the January – April dry season. Individual dry seasons vary in severity, and range in length from three to five months. The May – December wet season precipitation and annual totals also vary. Consequently the amount of water surplus to evapotranspiration and soil recharge needs and therefore available for overland flow, erosion, solute leaching, hydrolytic weathering, and catenary redistribution of solutes and colloids is temporally, as well as spatially, variable, ranging from zero up to about 1500 mm p.a.
  • The rainfall can attain potentially erosive intensities of up to 100 mm hr-1 for short periods.
  • There are strong gusts of wind that can uproot trees (Foster & Brokaw, 1996), especially in the west of the island. However, BCI lies to the south of the main hurricane tracks.