2006 Program
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Millipede abundance and their effect on the litter decomposition in the Tabonuco Forest
Juliana Belen-Rodríguez and Dr. Grizelle González
University of Puerto Rico, Mayaguez
International Institute of Tropical Forestry, US Forest Service
In this study, we quantify the density, biomass and richness of orders of millipedes in a tabonuco forest along a toposequence (ridges, slopes, valleys). Millipedes were surveyed from twelve (50 x 50cm) plots per site using the hand sorting method. The millipede biomass was determined on their fresh and dry weight basis. Others parameters measured was the soil pH, soil water content, soil temperature, and ground litter and humus biomass. There was a significant positive correlation between the soil pH and the number of millipede orders. Ridges positions were more acidic (lower) pH than slopes and valleys. Millipede density was no significantly correlated with soil / litter layer parameters except for Glomeridesmida order with a Person’s correlation equals to 0.804. The number of millipede orders was significantly and positively correlated with amount of wood and fruit.
Determining the presence of hummingbird flower mites in Heliconia caribaea in a humid tropical forest in Puerto Rico
Carolyn Cabrera, Dr. Elvia Meléndez-Ackerman and Dr. Ariel Díaz
University of Puerto Rico, Humacao
University of Puerto Rico, Rio Piedras
Hummingbird flower mites are very common in neotropical and subtropical plant species. They are inhabitants of plants that are pollinated by hummingbirds, and depend on these pollinators for movement from one flower to another. Presence of hummingbird pollinated plnats in Puerto Rico suggests the presence of mites but no records had been published yet. This research was conducted to determine if mites are present on the island. We compared sites with H. caribaea with sites that have more than one species of Heliconia and collected flowers were mites were determined to be present. We correlated mite abundance with number of bracts, flowers and inflorescences. Only inflorescences were significantly correlated. We found only one mite specie of the genus Rhinoseius for H. caribaea and two undetermined mite species for H. psittacorum from Zingiberales Gardens at Rio Grande.
The effect of light on the reproductive effort and success in Vanilla poitaei
Rebecca Clasen and Dr. James D. Ackerman
Loyola University, Chicago
University of Puerto Rico, Rio Piedras
At the El Verde Field Station located in the Luquillo Mountains of Puerto Rico, Vanilla poitaei has a low fruit success due to pollen and resource limitations. The purpose of this study is to determine the relationship of light quantity upon the reproductive effort and success of Vanilla poitaei. By measuring the light quantity along the vine using a fisheye telephoto lens and analyzing the photographs using Hemiview, the leaf area index (LAI) can be determined. By taking different readings such as stem size, leaf length, amount of mycorrhizal root infection of the vines and other measurements, we will see if there is any relationship between the effects of light on reproductive effort—assuming that plant vigor is necessary for reproductive effort (production of flowers). Also we will measure the reproductive success of the plant through daily recordings of pollinaria removal and pollination and see if there is any relationship between LAI and reproductive success. Using statistical analysis and JMP, we will determine the relationship between light, the reproductive effort, reproductive success and measured plant variables of vigor assuming that a more vigorous plant is more likely to show reproductive effort.
Environmental factors affecting Fungi development
Karla I. Claudio-Campos and Dr. Jean Lodge
University of Puerto Rico, Cayey
US Forest Service
Fungi are primary organic matter decomposers, making nutrients available to other organisms. The formation of litter mats resulting from the binding of leaves by fungi protects soil surface from erosion losses of soil organic matter and nutrients. Litter mats formation also protects soil from damages and prevents litter export (Lodge and Asbury 1988). This is a mechanism trough which fungi maintain humidity and soil fertility on steep slopes. This could be useful in rehabilitating areas affected by landslides and road cuts. The objectives of this research are to determine effects of sunlight and humidity on development of fungal mats, identify fungal species adapted to forest openings that may be useful for restoration and identify which fungal species are more able to retain litter on steep exposed slopes. The fungal species selected for this research are Marasmius guyanensis, Micromphale brevipes (terrestrial species), Marasmius crinus-equi and Micromphale sp. (aerial species) all found in the Luquillo Experimental Forest. The fungal species were placed in different basiets to observe its propagation between shade and partial shade areas. We selected four areas on the driveway of El Verde Field Station to put the fungal litter mats and a control to determine if fungal mats will retain more litter export than losses litter and which specie is more able to do it. Marasmius crinus-equi is the specie that has better development in partial and full shade area. We found that Micromphale brevipes was the specie which have better development in partial shade area because its driest than the environments sources of the other species. Micromphale brevipes which was retain more organic matter on steep slopeq based on the weight of sand and soil export.
Light environments in the riparian zones and roads of the Luquillo Experimental Forest
Joanne M. Fernández-Lopéz and Dr. Fred Scatena
University of Puerto Rico, Humacao
University of Pennsylvania
We describe the range of light that occurs in riparian areas and the amount of incident light reaching streams in the LEF. To measure light in these areas, we used an AccuPAR LP-80 ceptometer. We sampled fourteen streams of different sizes ranging from headwater streams to coastal plain streams. Percent of incident light was compared with drainage area, channel width, and within zones of streams. Results shows that small channel widths have lower percentages of incident light than bigger channel widths. When compared with drainage area, we found that streams with low catchment area are in lower light environments than bigger size streams. Significant differences were observed percent of incident light among vegetation zones groups in headwater streams.
Impacts of disturbances and elevation on arachnid diversity in the Luquillo Mountains
Danielle M. Knight and Dr. Paul Klawinski
University of Pennsylvania
William Jewell College
As many taxa are threatened through habitat or ecosystem destruction, humans lose biodiversity rapidly. Scientists have documented several species yet most agree there are thousands we still have no record of. Losing these undiscovered species means we have less goods and services to aid us. For instance, several pharmaceutical companies use plant extracts from rainforests for medicinal purposes. Performing biodiversity surveys provides a better understanding of speciation in target areas, whether the region is as small as a 100 sq. meter plot or an entire mountain range. Across different vegetation types in the Luquillo Mountains, we will collect spiders, focusing on the impacts of elevation and natural disturbances on their diversity. Natural disturbances manipulate arachnid speciation since hurricanes will completely change the physical structure of a forest rapidly; thus, altered vegetation affects arachnids because they build webs. Using the Coddington Protocol, samplers will perform aerial and ground searches, vegetation beating and will collect leaf litter samples for later processing with Burlese funnels. After specimen identification, we will derive an observed species count for each forest type and will then estimate mean species richness and standard error through Estimate S and also draw comparisons between community structures across different forest types.
Light attenuation in tropical streams ecosystems
Sharon Machín-Rivera and Dr. Jorge R. Ortiz-Zayas
University of Puerto Rico, Humacao
University of Puerto Rico, Rio Piedras
Light attenuation variables and flow were measured on a three tributaries stream of the Rio Espiritu Santo in the Caribbean National Forest, northeastern Puerto Rico. Light extinction coefficients were high in headwaters (1.14 to 13.65 m-1) and were lower in middle and large streams (0.19 to 2.83 m-1). Total suspended solids show the expected increase as stream order, in headwater were highest concentration (mean 10.474 mg/L) than in middle and large streams (4.363 mg/L). Secchi depth transparencies also show the expected decrease in headwater than in middle and large streams when the flow increase. A correlation of 0.80 was show between Secchi depth and flow in Sonadora. Increases in flow also were showed from headwaters to large streams. Results for the three steams suggest that exits more light attenuation in headwaters than in streams of higher order. Results also show those headwaters are more susceptible to change in flow and light attenuation.
Role of Invertebrates on leaf decomposition in tropical streams in the Luquillo Experimental Forest, Puerto Rico
Myriam O’Neill-Lopéz and Dr. Alonso Ramírez
University of Puerto Rico, Rio Piedras
We investigated the effect of macro invertebrates on the leaf decomposition in tropical streams in Luquillo Experimental Forest, Puerto Rico. We measured the lost in weight in the leaves and respiration rates using leaf packs that was incubated in artificial streams for about four weeks under the following treatment: aquatic insect larvae (Ephemeroptera), shrimps (Xiphocaris), crabs (Epiolobocera sinuatiforns), and control without invertebrates. The treatment with shrimp demostrated a significant increase in respiration rate (0.1616 mgO2/gDM/hr). While that the treatment with Ephemeroptera demonstrated a significant change in weight of the leaves (0.3175 g). The results demostrated that the macro invertebrates influence in the leaf decomposition in tropical streams.