tabonuco

Long-term influence of deforestation on tree species composition and litter dynamics of a tropical rain forest in Puerto Rico

Zou X, Zucca CP, Waide RB & McDowell WH (1995)
Long-term influence of deforestation on tree species composition
and litter dynamics of a tropical rain forest in
Puerto Rico. Forest Ecology and Management 78:
147–157.

Abstract: 
Understanding the long-term impact of deforestation on ecosystem structure and function of tropical forests may aid in designing future conservation programs to preserve biodiversity and sustain ecosystem productivity. We examined forest structure, tree species composition, litterfall rate, and leaf litter decomposition in a mid-successional forest (MSF) and an adjacent mature tabonuco forest (MTF) in the Luquillo Experimental Forest of Puerto Rico. Whereas the MTF site received limited human disturbance, the MSF site had been cleared for timber production by the beginning of this century and was abandoned after hurricanes struck the Luquillo Mountains in the 1920s and 1930s. We found that the MSF was dominated by successional tree species 50 years after secondary succession, and did not differ in tree basal area and litterfall rate from the MTF. Leaf decomposition rate in the MSF was higher than in the MTF, but this differencew as small.O ur resultss how that deforestation has long-term (over 50 years) influence on tree species composition and that recovery of leaf decomposition processes in secondary forest is relatively faster than that of tree species composition.

The Bromeliad Microcosm and the Assessment of Faunal Diversity in a Neotropical Forest

The Bromeliad Microcosm and the Assessment of Faunal Diversity in a Neotropical Forest
Barbara A. Richardson
Biotropica
Vol. 31, No. 2 (Jun., 1999), pp. 321-336

Abstract: 
The faunas of tank bromeliads were sampled over two years in three forest types at different elevations in the Luquillo Experimental Forest, Puerto Rico, and the diversity of their animal communities compared. Bromeliad plants behaved as islands in that, within forests, the species richness and abundance of their animal communities were significantly and positively correlated with increase in plant size. The amount of canopy debris they accumulated was similarly correlated with increase in plant size. Overall diversity was lowest in the dwarf forest, where plants were uniformly small. Animal communities were stable from year to year, and could be characterised for each forest type and for compartments within the plant. They showed a pattern of high dominance, which increased with elevation (McNaughton index 37, 54, and 73, respectively, for the tabonuco, palo colorado, and dwarf forest). Alpha-diversity for sites sampled in each year reflected net primary productivity (NPP) of the forest, declining with increasing elevation when animal abundance measures were used (jackknife estimates of Simpson's diversity index 6.54 & 11.04 [tabonuco], 3.53 & 6.22 [palo colorado], and 2.75 & 2.17 [dwarf forest]). Species richness over the two years, however, was highest in the intermediate palo colorado forest (187 species), compared to 146 and 88 in the tabonuco and dwarf forests, respectively. These figures were close to jackknife estimates of maximum species richness. The difference in species richness between tabonuco and palo colorado forests was significant in one year only. In addition to NPP, other factors, such as litter quality and the structural complexity of the habitat in the palo colorado forest, may have influenced species richness. The most abundant species in individual plants were also the most widely occurring, confirming known patterns of abundance and distribution in other functional groups. Diversity within bromeliad microcosms at different elevations supported known relationships between diversity, productivity, and habitat complexity along gradients and was not related to differences in the total bromeliad habitat available for colonization.

Basal area growth for 15 tropical tree species in Puerto Rico

Parresol, B. R. 1995. Basal area growth for 15 tropical trees species in Puerto Rico. Forest . Ecology and Management; 73:211-219.

Abstract: 
wildlife food and cover, and erosion control among other uses. Tree basal area growth data spanning 39 years are available on 15 species from eight permanent plots in the Luquillo Experimental Forest. The complexity of the rain forest challenges current forest stand modeling techniques. As a starting point individual tree basal area growth is modeled using the Chapman-Richards function constrained for hypothetical maximum tree size. In addition to initial tree diameter or basal area, significant explanatory variables are crown class, topographic position and degree of ground incline. Plots illustrate the differing growth patterns of the 15 tropical mixed/moist forest species. Two species exhibit exceptional growth. Buchenavia capitata (Vahl) Eichl. has basal area growth peaking at 87 cm2 year- ‘. The Manilkara bidentata (A. DC.) A. Chev. data show growth rates in excess of 60 cm* year-’ and the Chapman-Richards function indicates growth potential to a peak of 122 cm2 year-‘.

MODELING SPATIAL AND TEMPORAL PATTERNS OF SOIL ORGANIC CARBON IN TWO MONTANE LANDSCAPES: THE NORTHERN HARDWOODS, VERMONT AND THE TABONUCO FOREST, PUERTO RICO

Kristofer Dee Johnson, "Modeling spatial and temporal patterns of soil organic carbon in two montane landscapes: The northern hardwoods, Vermont and the tabonuco forest, Puerto Rico" (January 1, 2008). Dissertations available from ProQuest. Paper AAI3328590.

Abstract: 
Forest soils contribute to a significant portion of the world’s carbon flux due to both natural and anthropogenic changes. In terms of human management of carbon pools, forest soil organic matter (SOM) is important because it potentially stores carbon more permanently than living vegetation. Yet, this potential is poorly understood or managed for because of the difficulty in measuring changes in SOM pools over time and space. Modeling combined with intensive field sampling can help overcome these limitations because it extracts from empirically observed relationships to account for the components of SOM formation (topography, time, parent material, organisms and climate[fns2]). This study utilizes intensive field data, statistical models and process-based ecosystem models to investigate the spatial distribution and dynamics of soil organic carbon dynamics in two contrasting ecosystems – the northern hardwood forest in the Green Mountains, VT and the tabonuco forest in the Luquillo Experimental Forest, PR. In both forests landscape position emerged as the dominate factor in explaining SOM distribution. In Vermont, additional variation was explained by aspect and slope and in Puerto Rico additional variation was explained by landscape factors interrelated to soil drainage. Process-based modeling proved to be a useful management and experimental tool in cases were empirical approaches were impractical for both forests. In Vermont, three ecosystem models demonstrated a substantial reduction of soil organic carbon and harvestable biomass due to the removal of woody carbon by logging after 240 years of rotations. In Puerto Rico, the Century model showed that changes in litter quality and quantity were not likely responsible in explaining landscape level SOM differences. Overall, well drained soils located in colder climates stored the highest SOM whereas poorly drained and highly disturbed soils in steep humid climates stored the lowest SOM. This research demonstrates that although SOM amounts are highly variable over many spatial and temporal scales, intuitive relationships are borne out with modeling tools and by careful investigation of the five soil forming factors. Results also raise questions about how these ecosystems and their SOM pools may change in response to changing climate conditions of the future.

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.

Abstract: 
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.

A nitrogen budget for late-successional hillslope tabonuco forest, Puerto Rico

A Nitrogen Budget for Late-Successional Hillslope Tabonuco Forest, Puerto Rico
Tamara J. Chestnut, Daniel J. Zarin, William H. McDowell and Michael Keller
Biogeochemistry
Vol. 46, No. 1/3, New Perspectives on Nitrogen Recycling in the Temperate and Tropical Americas (Jul., 1999), pp. 85-108

Abstract: 
Nitrogen budgets of late successional forested stands and watersheds provide baseline data against which the effects of small- and large-scale disturbances may be measured. Using previously published data and supplemental new data on gaseous N loss, we construct a N budget for hillslope tabonuco forest (HTF) stands in Puerto Rico. HTF stands are subject to frequent hurricanes and landslides; here, we focus on N fluxes in the late phase of inter-disturbance forest development. N inputs from atmospheric deposition (4-6 kg N/ha/yr) are exceeded by N outputs from groundwater, gaseous N loss, and particulate N loss (6.3-15.7 kg N/ha/yr). Late-successional HTF stands also sequester N in their aggrading biomass (8 kg N/ha/yr), creating a total budget imbalance of 8.3-19.7 kg N/ha/yr. We surmise that this imbalance may be accounted for by unmeasured inputs from above- and belowground N-fixation and/or slow depletion of the large N pool in soil organic matter. Spatial and temporal variability, especially that associated with gaseous exchange and soil organic matter N-mineralization, constrain the reliability of this N budget.

Effect of Topography on the Pattern of Trees in Tabonuco (Dacryodes excelsa) Dominated Rain Forest of Puerto Rico

Effect of Topography on the Pattern of Trees in Tabonuco (Dacryodes excelsa) Dominated Rain Forest of Puerto Rico
Khadga Basnet
Biotropica
Vol. 24, No. 1 (Mar., 1992), pp. 31-42

Abstract: 
The structure, composition, and spatial patterns of tree species in two adjacent watersheds of the Luquillo Experimental Forest, Puerto Rico were investigated. Both watersheds had the same vegetational characteristics. Dacryodes excelsa! Sloanea berteriana, and Guarea guidonia were the most important trees in the overstory. A profile diagram, chisquare criterion, and multivariate techniques showed the same result: trees were related significantly to topographic variables. Large trees, especially the dominant species, tabonuco, were associated significantly with ridges and slopes. Size-class distributions of individual species varied as a function of broad ecological factors such as topography and disturbance regime. Past anthropogenic disturbance was still apparent in the pattern of distribution of large trees along the elevational gradients of the watersheds. Dacryodes excelsa is the dominant species, even though Sloanea berteriana has higher representation in smaller size-classes.

Ecological Consequences of Root Grafting in Tabonuco (Dacryodes excelsa) Trees in the Luquillo Experimental Forest, Puerto Rico

Ecological Consequences of Root Grafting in Tabonuco (Dacryodes excelsa) Trees in the Luquillo Experimental Forest, Puerto Rico
Khadga Basnet, F. N. Scatena, Gene E. Likens and Ariel E. Lugo
Biotropica
Vol. 25, No. 1 (Mar., 1993), pp. 28-35

Abstract: 
Root grafting was commonly found in tabonuco (Dacryodes excelsa Vahl), a dominant tree species of tabonuco forest in the subtropical wet forest of Puerto Rico. Over 60 percent of all stems and basal area of tabonuco occurred in unions, clumps of trees interconnected by root grafts. Self and intraspecific grafting were extensive, while interspecific grafting was not common in tabonuco trees. Seedlings and saplings did not show any grafting, probably because of their size or age. Grafted trees were taller and had a smaller crown/DBH ratio. Hurricane damage was significantly higher in isolated individual tabonuco trees than those in unions. Weak relationships between diameter class, area, and size of union, and inter-tree distances and the sum of the trunk circumferences of the two nearest neighbors suggested that a noncompetitive force such as root grafting was more important than competitive forces in maintaining the unions of tabonuco, and thus the forest community. A conceptual model of the costs and gains of tabonuco in unions is presented.
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