Study area, sites, and field station

The Coto Brus region of southern Costa Rica was once covered with premontane rain forest (Hartshorn 1983). This pleasant tropical landscape has a very rugged topography but surprisingly pleasant climate with abundant rain and warm but moderate temperatures. Work by Rachel Clement and Sally Horn on pollen profiles suggests that a fairly large native population occupied the Coto Brus area for several thousand years until about 500 years ago, when the amount of pollen from crop species (corn, squash, beans) drastically declined. Sadly, this probably represents the terrible wave of mortality that swept through many native populations after contact with Europeans allowed smallpox and other diseases to spread. Despite this tragedy, several groups of native Guymi continue to live in several indigenous reserves in the Coto Brus area of Costa Rica, and just over the border in Panama. In the 1960's the region was colonized by Europeans, mostly of Italian descent, who established a dairy industry. By the 1990's people realized that this agricultural enterprise was not economically sustainable and began exploring alternative land use strategies. This map shows Costa Rica, along with the location of the Cotobrus region, indicated by the red arrow in the lower right.

Our study area encompasses the area surrounding the Wilson Botanical Garden / Las Cruces Biological Station of the Organization for Tropical Studies. It is near the town of San Vito, Coto Brus canton. The topography is mountainous, highly dissected and downcut,ranging between 600 and 1600 m elevation. This 1992 air photo shows a typical landscape of the Cotobrus region, consisting of pastures, plantations, forest, etc. The yellow boxes indicate our five study sites. To the right is the edge of the 235-ha Las Cruces forest preserve; note that each of our study sites borders on a forest fragment.

The soils within the proposed study area, according to the 1:200,000 soil map, are of three types: typic dystrandept, andic humitropept, and lithic dystropept (Perez & Ramierez 1979). Typic dystrandepts, renamed ultic hapludands, are typical of high elevation isomesic perhumic regions underlain by rhyolitic volcanic ashes. These have a low bulk density, a high P fixation potential and pH dependent anion exchange capacity. A diagnostic property is that many have field soil moisture contents in excess of 100% of the dry weights. Some may upon drying become irreversably hardened into aggregates. Andic humitropepts have properties of volcanic ash but not enough to be classed as andisols (soils of volcanic origin). They are acid with high organic matter. They are often used to support coffee and potatoes. Lithic dystrapepts are shallower soils of recent erosion surfaces having bedrock at 50 cm depth or less. Weatherable minerals release nutrients and exchangeable aluminum. All of these soils have a low base saturation.

The climate of the Cotobrus area is mild and fairly constant. Precipitation varies somewhat, being low during January through March, and higher the rest of the year. Temperature is relatively constant year-round. This figure shows the 30- year averages for the Las Cruces biological station, on a monthly basis.

The vegetation cover information is available from a set of 93 air photos taken in February 1992 around Las Cruces. The coverage extends from the Osa Peninsula north to Paso Real and La Amistad and then from the Panamanian border west to the Coast near Sierpe. The scale is about 1:40,000.
According to a recent GIS analysis of land use in the Coto Brus canton, pastures are the most extensive type of land use, followed by coffee plantations, and then by row crops (Juarez 1994).

Las Cruces Biological Station

A modern, comfortable facility just outside of the village of San Vito, in Coto Brus canton.

The Las Cruces Biological Station, owned and operated by the Organization for Tropical Studies, is located just outside the town of San Vito. The central, cultivated 8 hectares is home to the Wilson Botanical Garden, a beautiful, internationally-renowned facility which boasts the world's largest collection of palms. These two photos show the front and back of the dining hall, a beautiful structure built in 1996, and located on a hilltop with splendid views in several directions. Beyond the Garden, the Station owns a 235-ha forest preserve and some adjacent pastures.

Researchers, tourists and students are housed in attractive, clean cabins located near the new dining hall and the research lab in the center of the grounds. This photo shows some of the new (1995) cabins, in which visiting tourists and students stay. Nearby is the Wilson house, the original building on the property, which dates from the 1960s, and consists of several bunkrooms, the gift shop, and classrooms. A newer building (1997) near the dining hall holds the director's apartment, the library, and the new herbarium. Many buildings date from the mid-1990's because a terrible fire in 1994 destroyed much of the Las Cruces infrastructure; although generous donations have allowed newer and better structures to be rebuilt.

The older cabins are used for housing researchers. They are quite comfortable, and slightly closer to the forest than the new cabins, which allows some better opportunities for birdwatching from the back porch, and occasionally witnessing monkeys in the trees just outside the windows of the old cabins. These photos show the front and back of one of the older cabins.

Researchers can make use of the laboratory facility, located adjacent to the dining hall. The lab has basic scientific supplies and equipment, but researchers must bring their own advanced instrumentation or equipment. Classes utilize the lab when multiple groups are at the station, so it has large tables and plenty of chairs. Computers are available for general use are in the laboratory, with connections to the Internet.