forest

Forests of porto rico past, present, and future and their physical and economic environment

Murphy, L. S. (1916) Forests of Porto Rico—Past, Present, and Future. Washington,
DC: U.S. Government Printing Office, U.S. Department of Agriculture Bulletin
No. 354.

Valuing water and sediment tradeoffs between forest and pasture in montane tropical environments in Puerto Rico

Gingold, E. A. (2007). Valuing water and sediment tradeoffs between forest and pasture in montane tropical environments in Puerto Rico. University of Pennsylvania Scholarly Commons. Retrieved 3/20/11 from http://repository.upenn.edu/cgi/viewcontent.cgi?article=1010&context=mes...

Abstract: 
Effective land use policy must weigh both the private and public costs and benefits of converting forests to alternate land uses. This project assesses the private and public impacts of forest to pasture conversion in the montane regions of Puerto Rico. Due to the island's water supply problems, hydrologic ecosystem services were found to be the most significant resource impacted. The value of carbon sequestration lost through conversion was found to range from 9-36 $/ha/yr. The value of other ecosystem services, notably recreation and biodiversity, were found to be highly significant in certain localities but small on an average island-wide basis. The model created in this study found that the public costs of reservoir sedimentation resulting from increased erosion and the higher incidence of landslides on pastures outweigh the public benefits of increased runoff in areas where with slopes of approximately 21o and a Revised Universal Soil Loss Equation topographic factor greater than 6.5. Results were highly dependent on the amount of sediment that is transported from the pasture to the reservoir (e.g. the sediment delivery ratio) and the marginal value of water. The private returns to pasture (400 $/ha/yr) were generally found to be greater than the sum of the public costs. The results suggest that policy-makers should take local environmental variation into account when designing forest conservation strategies. Policies should target areas with high slopes and high sediment delivery ratios.

Experimental Removal of Insectivores from Rain Forest Canopy: Direct and Indirect Effects

Dial, Roman, and Jonathan Roughgarden. 1995. Experimental Removal of Insectivores from Rain Forest Canopy: Direct and Indirect Effects. Ecology 76:1821–1834

Abstract: 
This study considered the effects of insectivorous Anolis lizards on a large, complex food web of arthropods and associated herbivory in a tropical rain forest canopy. We excluded Anolis lizards for 6 mo from 20—30 m high tree crowns in Puerto Rican rain forest. Simultaneous with lizard exclusion, we sampled orb spiders, airborne arthropods, and leaf arthropods in lizard removal crowns and in controls. We also sampled herbivory at the end of the experiment. Lizard removal had strong, statistically significant, positive effects on arthropods >2 mm in length and weak negative effects on arthropods <2 mm. Parameters of arthropod body size distributions differed between removals and controls for leaf arthropods, but not for airborne arthropods. Among arthropod taxa >2 mm, both predatory, i.e., orb spiders and parasitic Hymenoptera, and nonpredatory forms, i.e. Diptera, Coleoptera, Orthoptera, and Blattaria, showed strong significant and positive responses to lizard removal. Large Psocoptera, Homoptera, leaf spiders, and ants did not show significant overall responses to lizard removal. Frequency of herbivore damage on new leaves was positively correlated with abundance of Orthoptera and Blattaria. This damage was significantly greater in lizard removal crowns than in controls, indicating an indirect effect of anoles on plants. The indirect effect of lizards on small arthropods through the predatory anthropod pathway appeared weak. Results of lizard removal shown by this study corroborate other lizard removal studies from more xeric, ground—level habitats with simpler food webs in the West Indies, particularly with respect to orb spiders and herbivory. Taken together with the results of similar experiments performed in trophically less complex systems, this experiment suggests that food web size is less important than body size in determining interaction strength between community members.

THE EARTHWORMS OF BANO DE ORO, LUQUILLO EXPERIMENTAL FOREST, PUERTO RICO

Borges, S. and M. Alfaro. 1997. The earthworms of
Baño de Oro, Luquillo Experimental Forest, Puerto
Rico. Soil Biol. Biochem. 29:231-234.

Abstract: 
The earthworm fauna of the four forest types at the Batio de Oro region of the Luquillo Experimental Forest was sampled over 6 months. Eight species were found: two Glossoscolecidae, one Ocnerodrilidae, four Megascolecidae, and one Eudrilidae. The total species density and biomass showed no significant correlation to forest type or soil depth, but some species did show different distribution patterns according to certain soil properties. Exotic species were more abundant, but native species accounted for most of the biomass. Species number and density were low when compared with similar studies in other neotropical forests. This could be due to the high moisture content of the soils and its effects on other soil properties.
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