Scatena F.N.

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.

Culvert flow in small drainages in montane tropical forests: observations from the Luquillo Experimental Forest of Puerto Rico.

Scatena, F. N. 1990. Culvert flow in small drainages in montane tropical forests: observations from the Luquillo Experimental Forest of Puerto Rico. . Tropical Hydrology and Caribbean Water Resources. :237-246.

Abstract: 
This paper describe the hydraulics of unsubmerged flow for 5 culverts in the Luiquillo Esperimental Forest of Puerto Rico. A General equation based on empirical data is presented to estimate culvert discharge during unsubmerged conditions. Large culverts are needed in humid tropical montane areas than in humid temperatute watersheds and are usually appropriate only for drainage less than 1km2.

Forest Floor Decomposition Following Hurricane Litter Inputs in Several Puerto Rican Forests

Rebecca Ostertag, Frederick N. Scatena, and Whendee L. Silver. 2003. Forest Floor Decomposition Following Hurricane Litter Inputs in Several Puerto Rican Forests. Ecosystems 6 :261-273.

Abstract: 
Hurricanes affect ecosystem processes by altering resource availability and heterogeneity, but the spatial and temporal signatures of these events on biomass and nutrient cycling processes are not well understood. We examined mass and nutrient inputs of hurricane-derived litter in six tropical forests spanning three life zones in northeastern Puerto Rico after the passage of Hurricane Georges. We then followed the decomposition of forest floor mass and nutrient dynamics over 1 year in the three forests that experienced the greatest litter inputs (moist, tabonuco, and palm forests) to assess the length of time for which litter inputs influence regeneration and nutrient cycling processes. The 36-h disturbance event had litterfall rates that ranged from 0.55 to 0.93 times annual rates among the six forests; forest floor ranged between 1.2 and 2.5 times prehurricane standing stocks. The upperelevation forest sites had the lowest nonhurricane litterfall rates and experienced the lowest hurricane litterfall and the smallest relative increase in forest floor standing stocks. In the three intensively studied forests, the forest floor returned to prehurricane values very quickly, within 2–10 months. The palm forest had the slowest rate of decay (k  0.74  0.16 y–1), whereas the tabonuco forest and the moist forest had similar decay rates (1.04  0.12 and 1.09  0.14, respectively). In the moist forest, there were short-term increases in the concentrations of nitrogen (N), hosphorus (P), calcium (Ca), and magnesium (Mg) in litter, but in the other two forests nutrient concentrations generally decreased. The rapid disappearance of the hurricane inputs suggests that such pulses are quickly incorporated into nutrient cycles and may be one reason for the extraordinary resilience of these forests to wind disturbances.

Metabolism of a tropical rainforest stream

Ortiz-Zayas, J.R. et al. Metabolism of a tropical rainforest stream. Journal of the North American Benthological Society, Volume 24, No. 4, pages 769–783.

Abstract: 
Gradients in photosynthesis (P) and respiration (R) were measured on an unperturbed portion of the Rio Mameyes, a tropical stream in the Luquillo Experimental Forest, northeastern Puerto Rico. Rates of P, which were similar to those of streams in temperate-deciduous forests, were low in the heavily canopied headwaters (<70 g O2 m−2 y−1) and were higher (453–634 g O2 m−2 y−1) in middle and lower reaches. Periphyton biomass did not show the expected increase as the canopy opened downstream, probably because of increasing herbivory in downstream reaches. Rates of R, which were much higher than in most temperate streams, also were lower in the headwaters (767 g O2 m−2 y−1) than in the middle and lower reaches (1550–1660 g O2 m−2 y−1). High rates of R and suppressed periphyton abundance caused annual P/R to be <<1 from headwaters to lower reaches. Results for the Rio Mameyes suggest that intense herbivory, which is favored by the presence of large herbivores and consistently high temperatures, may be more typical of tropical than temperate streams. Results also show that the tropical rainforest provides the stream with sufficient amounts of labile organic C to support high rates of respiration over long distances across the basin.

Non-Indigenous Bamboo along Headwater Streams of the Luquillo Mountains, Puerto Rico: Leaf Fall, Aquatic Leaf Decay and Patterns of Invasion

O'CONNOR, PAUL J.; COVICH, ALAN P.; SCATENA, F. N.; LOOPE, LLOYD L. 2000. Non-indigenous bamboo along headwater streams of the Luquillo Mountains, Puerto Rico: leaf fall, aquatic leaf decay and patterns of invasion. Journal of Tropical Ecology 16 :499-516.

Abstract: 
The introduction of bamboo to montane rain forests of the Luquillo Mountains, Puerto Rico in the 1930s and 1940s has led to present-day bamboo monocultures in numerous riparian areas. When a non-native species invades a riparian ecosystem, in-stream detritivores can be affected. Bamboo dynamics expected to in¯uence stream communities in the Luquillo Experimental Forest (LEF) were examined. Based on current distributions, bamboo has spread downstream at a rate of 8 m y-1. Mean growth rate of bamboo culms was 15.3 cm d-1. Leaf fall from bamboo stands exceeded that of native mixed-species forest by c. 30% over a 10-mo study. Bamboo leaves (k = -0.021), and leaves from another abundant riparian exotic, Syzygium jambos (Myrtaceae) (k = -0.018), decayed at relatively slow rates when submerged in streams in ®ne-mesh bags which excluded macro-invertebrate leaf processors. In a second study, with leaf processors present, bamboo decay rates remained unchanged (k = -0.021), while decay rates of S. jambos increased (k = -0.037). Elemental losses from bamboo leaves in streams were rapid, further suggesting a change in riparian zone / stream dynamics following bamboo invasion. As non-indigenous bamboos spread along Puerto Rico streams, they are likely to alter aquatic communities dependent on leaf input.

Background and Catastrophic Tree Mortality in Tropical Moist, Wet, and Rain Forests

Background and Catastrophic Tree Mortality in Tropical Moist, Wet, and Rain Forests
Ariel E. Lugo and F. N. Scatena
Biotropica
Vol. 28, No. 4, Part A. Special Issue: Long Term Responses of Caribbean Ecosystems to Disturbances (Dec., 1996), pp. 585-599

Abstract: 
The process of tree mortality has dimensions of intensity, spatial, and temporal scales that reflect the characteristics of endogenic processes (i.e., senescence) and exogenic disturbances (i.e., severity, frequency, duration, spatial scale, and points of interaction with the ecosystem). Tree mortality events expressed as percent of stems or biomass per unit area, range in intensity from background (<5% yr-1) to catastrophic (>5% yr-1), in spatial scale from local to massive, and in temporal scale from gradual to sudden (hours to weeks). Absolute annual rates of background tree mortality (biomass or stem ha-1 yr-1) can vary several fold depending on stand conditions and tend to increase with stem density. The ecological effects of a catastrophic, massive, and sudden tree mortality event contrast with those of background, local, and gradual tree mortality in terms of the direction of succession after the event, community dynamics, nutrient cycling, and possibly selection on trees. When standardized for the return frequency of disturbance events, area, and topography, the ranking of tree mortality events (trees ha-1 century-1) in the Luquillo Experimental Forest is: background > hurricanes > individual tree fall gaps > landslides. Estimates of vegetation turnover rates require long-term and spatial analysis to yield accurate results.

Fine Litterfall and Related Nutrient Inputs Resulting From Hurricane Hugo in Subtropical Wet and Lower Montane Rain Forests of Puerto Rico

Fine Litterfall and Related Nutrient Inputs Resulting From Hurricane Hugo in Subtropical Wet and Lower Montane Rain Forests of Puerto Rico
D. Jean Lodge, F. N. Scatena, C. E. Asbury and M. J. Sanchez
Biotropica
Vol. 23, No. 4, Part A. Special Issue: Ecosystem, Plant, and Animal Responses to Hurricanes in the Caribbean (Dec., 1991), pp. 336-342

Abstract: 
On 18 September 1989 Hurricane Hugo defoliated large forested areas of northeastern Puerto Rico. In two severely damaged subtropical wet forest sites, a mean of 1006-1083 g/m$^2$, or 419-451 times the mean daily input of fine litter (leaves, small wood, and miscellaneous debris) was deposited on the forest floor. An additional 928 g/m$^2$ of litter was suspended above the ground. A lower montane rain forest site received 682 times the mean daily fine litterfall. The concentrations of N and P in the hurricane leaf litter ranged from 1.1 to 1.5 and 1.7 to 3.3 times the concentrations of N and P in normal leaffall, respectively. In subtropical wet forest, fine litterfall from the hurricane contained 1.3 and 1.5-2.4 times the mean annual litterfall inputs of N and P, respectively. These sudden high nutrient inputs apparently altered nutrient cycling.

Eutrophic overgrowth in the self-organization of tropical wetlands illustrated with a study of swine wastes in rainforest plots

Kent,Roberta; Odum, H.T.; Scatena, F.N. 2000. Eutrophic overgrowth in the self-organization of tropical wetlands illustrated with a study of swine wastes in rainforest plots. Ecological Engineering 16 255-269.

Abstract: 
The relationship of plant species diversity to cultural eutrophy in tropical wetlands was studied in Puerto Rico with experimental plots, a survey of 25 eutrophic sites developing from the wastes of society, and a simulation mini-model. The model is a quantitative hypothesis which contains the mechanisms to maximize empower (gross production) by reinforcing low diversity, net production overgrowth when resources are in excess, but switches to high diversity efficiency and recycle to maximize gross production when excess resources are absent. To study self-organization with eutrophy, six wetland plots (32 m) were seeded with many plant species and treated for five months with pig wastewaters and control plots with groundwater. Vegetation was seeded: (1) with seed bank; (2) with ten species of local rainforest and wetland trees (60 individuals in each plot); and (3) with weedy species invading from fertile surroundings. The fertilized waste plots filled in with vegetation in less than half the time (9 weeks) required for the clear water control plots (21 weeks). Vegetative diversity in both waste and control plots was maximum (2.73–3.34 bits per individual) shortly before 100% cover was reached, and then declined with the competitive overgrowth of a few species (mixed grasses and Commelina diffusa). Of the planted seedlings, there was little growth, and individuals of only four species survived. Survival of Andira inermis and Cyrilla racemiflora was 42 and 53%, respectively. Dominants of oligotrophic wetlands (Pterocarpus officinalis and Prestoea montana) were displaced. A survey of 25 other wetland sites, receiving high nutrient waters from developments, found low diversity overgrowth, but different species prevailing. Eighty-five species were involved in wetland self-organizational processes and ecological engineering management. Eutrophic wetlands, such as those released from sugar cane closure in Puerto Rico and elsewhere, may be in a state of marshy, arrested succession because there may not be a forest species already adapted for rapid reforestation of the excess nutrient habitat. The study provides evidence of the overgrowth principle as the natural means for ecological engineering of eutrophic interfaces between the current civilization and environment.

Physical Aspects of Hurricane Hugo in Puerto Rico

Scatena, F. N., and Larsen, M. C., 1991, Physical aspects of Hurricane Hugo in Puerto Rico: Biotropica, v. 23, no. 4A, p. 317-323.

Abstract: 
On 18 September 1989, the western portion of Hurricane Hugo crossed eastern Puerto Rico and the Luquillo Experimental Forest (LEF). Storm-facing slopes on the northeastern part of the island that were within 15 km of the eye and received greater than 200 mm of rain were most affected by the storm. In the LEF and nearby area, recurrence intervals associated with Hurricane Hugo were 50 yr for wind velocity, 10 to 31 yr for stream discharge, and 5 yr for rainfall intensity. To compare the magnitudes of the six hurricanes to pass over Puerto Rico since 1899, 3 indices were developed using the standardized values of the product of: the maximum sustained wind speed at San Juan squared and storm duration; the square of the product of the maximum sustained wind velocity at San Juan and the ratio of the distance between the hurricane eye and San Juan to the distance between the eye and percentage of average annual rainfall delivered by the storm. Based on these indices, Hurricane Hugo was of moderate intensity. However, because of the path of Hurricane Hugo, only one of these six storms (the 1932 storm) caused more damage to the LEF than Hurricane Hugo. Hurricanes of Hugo's magnitude are estimated to pass over the LEF once every 50-60 years on average.

Fine Litterfall and Related Nutrient Inputs Resulting From Hurricane Hugo in Subtropical Wet and Lower Montane Rain Forests of Puerto Rico

Fine Litterfall and Related Nutrient Inputs Resulting From Hurricane Hugo in Subtropical Wet and Lower Montane Rain Forests of Puerto Rico
D. Jean Lodge, F. N. Scatena, C. E. Asbury and M. J. Sanchez
Biotropica
Vol. 23, No. 4, Part A. Special Issue: Ecosystem, Plant, and Animal Responses to Hurricanes in the Caribbean (Dec., 1991), pp. 336-342

Abstract: 
On 18 September 1989 Hurricane Hugo defoliated large forested areas of northeastern Puerto Rico. In two severely damaged subtropical wet forest sites, a mean of 1006-1083 g/m$^2$, or 419-451 times the mean daily input of fine litter (leaves, small wood, and miscellaneous debris) was deposited on the forest floor. An additional 928 g/m$^2$ of litter was suspended above the ground. A lower montane rain forest site received 682 times the mean daily fine litterfall. The concentrations of N and P in the hurricane leaf litter ranged from 1.1 to 1.5 and 1.7 to 3.3 times the concentrations of N and P in normal leaffall, respectively. In subtropical wet forest, fine litterfall from the hurricane contained 1.3 and 1.5-2.4 times the mean annual litterfall inputs of N and P, respectively. These sudden high nutrient inputs apparently altered nutrient cycling.
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