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.

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.

The effect of human activity on the structure and composition of a tropical forest in Puerto Rico

Garcia-Montiel, D.C.; Scatena, F.N. 1994. The effect of human activity on the structure and composition of a tropical forest in Puerto Rico. Forest Ecology and Management, 63 :57-78.

From European settlement to the 1940s, the Bisley watersheds of the Luquilio Experimental Forest, Puerto Rico, were used for agroforestry, selective logging, charcoal production, and timber management. Each of these activities affected different parts of the landscape in different ways and at different times. After nearly 50 years of unhindered regeneration, six impacts remain apparent: ( 1 ) shifts in the dominance and age structure of canopy species; (2) immigration of subcanopy crop species and the establishment of banana as a riparian dominant; (3) increases in the importance of canopy species used for coffee shade; (4) the impoverishment of certain commercial timber species; (5) an increase in the density of palms around abandoned charcoal kilns; (6) a reduction in the regeneration of canopy species around abandoned charcoal kilns. Changes in the above-ground nutrient pool may also have occurred. Human disturbances in the study site were progressive rather than discrete events, had adverse impacts on forest regeneration, and increased the spatial heterogeneity of the forest.

Changes in the herbaceous and vine communities at the Bisley Experimental Watersheds, Puerto Rico, following Hurricane Hugo

Chinea, Jesus D. 1999. Changes in the herbaceous and vine communities at the Bisley Experimental Watersheds, Puerto Rico, following Hurricane Hugo.. Can. J. For. Res. 29: 1433-1437 .

While herbaceous species and vines constitute a minor portion of the biomass in tropical closed forest ecosystems, they account for a substantial portion of the diversity of these ecosystems and become more conspicuous after natural disturbances. This study describes the changes in abundance and diversity of the herbs and vines during 5 years following Hurricane Hugo at the Bisley Experimental Watersheds, Puerto Rico. The cover of herbs, ferns, and vine species was sampled within a 5-m2 area in 25 randomly chosen circular permanent plots within the 13 ha of these watersheds. Sampling was done 12, 18, 36, 48, and 60 months after the hurricane. One year after the hurricane the overall mean herbaceous cover in the watersheds was 55%. Four years later, the cover and species richness of herbs and vines, but not ferns, had been significantly reduced. The only change in species diversity (H¢ ) was a significant increase in ferns. These changes are explained in terms of the extent and spatial variability of the hurricane damage, as well as changes in the tree component of this ecosystem.

An Annotated List of the Flora of the Bisley Area, Luquillo Experimental Forest, Puerto Rico 1987 to 1992

Chinea, J. D., R. J. Beymer, C. Rivera, I. Sastre de Jesu´ s, and F.
N. Scatena. 1993. An annotated list of the flora of the Bisley
Area, Luquillo Experimental Forest, Puerto Rico 1987 to 1992.
General Technical Report SO-94:1–12. U.S. Department of Agriculture,
Southern Forest Experiment Station, New Orleans.

Known species of plants, including bryophytes and ferns, are listed for the area of the Bisley experimental watershed area, a subtropical wet forest in the Luquillo Mountains of northeastern Puerto Rico.

Changes in Structure, Composition, and Nutrients During 15 Yr of Hurricane-Induced Succession in a Subtropical Wet Forest in Puerto Rico

Heartsill Scalley, Tamara; Scatena, Frederick N.; Lugo, Ariel E.; Moya, Samuel; Estrada Ruiz, Carlos R. 2010. Changes in structure, composition, and nutrients during 15 years of hurricane-induced succession in a subtropical wet forest in Puerto Rico. Biotropica. 42(4): 455-463.

The trajectory of hurricane-induced succession was evaluated in a network of forest plots measured immediately before and 3 mo, 5, 10, and 15 yr after the direct impact of a Category 4 hurricane. Comparisons of forest structure, composition, and aboveground nutrients pools were made through time, and between species, lifehistory groups and geomorphic settings. The hurricane reduced aboveground biomass by 50 percent, causing an immediate decrease in stem density and diversity indices among all geomorphic settings. After 15 yr, basal area and aboveground biomass returned to pre-hurricane levels, while species richness, diversity indices, and stem densities exceeded pre-hurricane levels. Differences in species composition among geomorphic settings had not returned after 15 yr but differences in stem densities and structure were beginning to emerge. Significant differences were observed in the nutrient concentration of the three species that comprised the most aboveground biomass, and between species categorized as secondary high-light species and primary, low-light species. Species whose abundance was negatively correlated with the mature forest dominant also had distinct nutrient concentrations. When total aboveground nutrient pools were compared over time, differences in leaf nutrients among species were hidden by similarities in wood nutrient concentrations and the biomass dominance of a few species. The observed successional trajectory indicates that changes in species composition contributed to fast recovery of aboveground biomass and nutrient pools, while the influence of geomorphic setting on species composition occurs at time scales 415 yr of succession.
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