An Introduction to the Physiography and History of the Bisley Experimental Watersheds in the Luquillo Mountains of Puerto Rico

Scatena, F. N. 1989. An introduction to the physiography and history of the Bisley Experiment Watersheds in the Luquillo
Mountains of Puerto Rico. General Technical Report SO-72:1–
22. U.S. Department of Agriculture, Southern Forest Experiment
Station, New Orleans.

Abstract: 
This paper summarizes the physiographic setting and historical uses of the Bisley experimental watersheds. These watersheds are the site of long-term watershed studies in the Luquillo Experimental Forest of Puerto Rico. Each of these watersheds drains deep, clayey soils that overlie a highly dissected terrain underlain by volcanoclastic sandstones. The drainages are covered by secondary tabonuco type forests and receive about 3,500 mm&r of rainfall. Since European settlement, about 490 years ago, the study area has been explored for precious ores, cultivated, and selectively logged. The major obstacle to the exploitation of the resources of the watersheds has been inaccessibility. High rainfall, steeply sloping terrain, and slippery clay soils combine to make transportation in the area difficult. The most rapid change to the Bisley landscape occurred at the end of the 19th century and the beginning of the 20th century. During this time, local agricultural activity was at a maximum, timber was being exported from the region, and copper mines were active in the Rio Blanc0 area. In addition to human activity, major hurricanes occurred in 1892 and 1932. Human-induced disturbance in the watersheds has been selective in both space and time. The pattern of disturbance is contrary to that described in other temperate and tropical forests. Anthropogenic disturbance in these watersheds has apparently increased the spatial heterogenity of the forest. The success of both natural and induced regeneration in the area suggests that the impact of human disturbance was greater on forest structure than on its long-term productivity.