Monteverde Institute: Tropical Ecology and Conservation

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  Macrofungal community richness at different distances from a cloud forest stream, August 2008

  Elizabeth Place

  The purpose of this study was to examine macrofungal community richness at different distances from the Quebrada Máquina in the cloud forest of Monteverde, Costa Rica. Twenty transects no closer than ten meters apart were tested. Each transect contained a 1X 1 m2 plot positioned at zero, five, ten, fifteen, and twenty meters from the stream edge. Fungi were counted and photographed and weather and substrate type were recorded. I predicted to find more macrofungal richness closer to the river because of water and sunlight availability. However, using Friedman’s method for randomized blocks, I found a Chi squared value of 9.18 (df = 4, p > 0.05), which shows no statistical significance in fungal community richness between the five different distances. However, graphing mean number of species found per distance, we can see a trend. It shows that fungal richness is highest at the middle distances. I also tested distribution of species on substrates, and found dead wood was the most common. A Chi squared Goodness of Fit Test (assuming substrate abundance was equal) showed that the distribution differed significantly from the expected distribution (Chi squared = 315.5, df = 5, p < 0.001). These results therefore imply that there may be more dead wood at the middle distances than at the closest and farthest distances, or that other conditions are more favorable to fungi there.

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  Patterns of petiole abundance and diversity in bark beetles (Scolytinae) of Cecropia trees in Monteverde, Costa Rica, August 2008

  Sonali Gandhi

  Cecropia trees regularly shed their woody, large petioles year round. This provides bark beetles from the family Scolytinae with a dependable and stable microhabitat. Bark beetles bore into the petioles, lay their eggs, and feed on the pith (Wood 1983). This study was conducted in Monteverde, Costa Rica. It examined the abundance and diversity of bark beetles between Cecropia polyphlebia in the Monteverde Cloud Forest (1550 meters) and an intermediary phenotype at Bajo del Tigre (1400 meters). It also investigated the percent of petioles colonized, species richness, evenness, and the influence of petiole moisture and length on the abundance and diversity of beetles. I analyzed 90 dead, woody petioles from the ground and from hanging vegetation from each site. Petioles were dissected and beetles were removed and identified by one of six Scolytinae morphospecies. Differences in the abundance and diversity of beetles between the two species were then compared. This study suggests that there was no difference in species diversity between the two tree species (p > 0.05). However, a difference in abundance between the hybrid phenotype and C. polyphlebia was observed. The hybrid phenotype possessed a higher abundance of beetles. Also moisture content (ANCOVA, F = 4.93, df = 2, p = 0.0083), the species of Cecropia (ANCOVA, F = 11.2, df = 1, p =0.001), and petiole length with Cecropia species (ANCOVA, F = 5.16, df = 1, p = 0.0244) had an influence on the abundance of beetles. The higher abundance of beetles in the hybrid phenotype could indicate differences in interspecific competition due to phenotypic traits of the Cecropia species. Differences in moisture content and petiole length between the two Cecropia species may reflect petiole preference and favorability of tree hosts. Furthermore, the higher abundance of beetles in the lower elevation hybrid phenotype could indicate that the majority of bark beetles may not be affected by climate change unlike many other species of animals and plants that are being severely impacted by the increasing temperatures.

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  Species richness and abundance of dragonflies and damselflies (Odonata) at different elevations in Monteverde, Costa Rica, August 2008

  Christy Conley

  Dragonflies and damselflies (Odonata) are very sensitive to differences in environmental conditions such as temperature, oxygen levels and amount of forest cover (Ramírez 2000). This study focuses on Odonata species in Monteverde, Costa Rica within the Lower Montane Wet habitat. I hypothesized that variations in altitude would influence Odonata biodiversity, abundance and species richness. I used a butterfly net to collect Odonata samples at five different elevations located at between altitudes of 1425 m and 1525 m. There was no significant correlation between altitude and species richness (r^2=0.3331; p=0.450185), H’ (r^2=0.03221; p=0.188120), evenness (r^2=0.03221; p=0.188120), Odonata abundance (r^2=0.03221; p=0.188120) and Brechmorhoga rapax abundance (r^2=0.1099; p=0.872889). A significant positive correlation was found, however, between the abundance of Cora chirripa and altitude (r^2=0.3809; R=0.974679; N=5; p=0.004818). This may indicate that Cora chirripa is more sensitive to environmental factors determined by altitude than other Odonata species.

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  Species richness of vascular plants in the riparian transition zones of the Quebrada La Cruz and the Quebrada Socorro in Monteverde, Costa Rica, August 2008

  Rhiannon Cook

  While many studies have been performed to determine the effects of urbanization in the later stages of development on biodiversity, little is known about how biodiversity is affected by urbanizations in its early phases. This research evaluates how the biodiversity of herbaceous plants in the riparian ecotones of two rivers is affected in the transition from a rural to town setting. Morpho species diversity was sampled on two rivers of the Monteverde, Costa Rica area; the Quebrada Socorro, relatively unaffected by human influence, and the Quebrada La Cruz, which is greatly influenced by both the growth of town infrastructure and agriculture. Ten sites were sampled at equal elevations on each river. Shannon-Weiner diversity index values were compared from each river at each elevation. It was found that the Socorro had a higher diversity value (H’ = 3.40) than the La Cruz (H’ = 2.63) (Modified t-test, t = -8.55; df = 246.95; P < 0.05). In addition, there were significant differences in the H’ values at six out of the ten different elevations, and of those six elevations, five had higher H’ values on the Socorro. Other observations found that species plant composition was radically different between the two rivers. This research implies a change in plant species composition and loss of diversity in riparian ecotones with increased urbanization and human influence which has repercussions for stream ecosystem food webs that depend on a diverse riparian input of leaf litter at the primary trophic level.

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  The dynamics of prey capture of the colonial, orb-weaving spider Metabus gravidus (Araneidae) in Monteverde, Costa Rica, August 2008

  Signe Spencer

  Prey capture dynamics of the colonial, orb-weaving spider Metabus gravidus (Araneidae) are based on individuals. It is possible that prey caught in certain locations of the web will stimulate more reactions, and that different types of prey will stimulate variable reactions. Since the members of the colony live close to one another, it is also possible that spiders exhibit competition over prey. Different insects were dropped into various locations of individual orbs in order to observe reactions. The spiders did not seem to prefer whether prey was dropped closer or further from the center of the web (Chisquared goodness of fit, l2 = 0.684, P = 0.710, DF = 2); number of captures did not depend on location either (Chi-squared goodness of fit, l2 = 0.651, P= 0.651, DF = 2). Grasshoppers generated medium-speed reactions, but overall the spiders preferred moths to grasshoppers or ants (chi-squared goodness of fit, l2 =14.88, P = 0.006, DF = 2). It seems that variation in prey stimulates different behaviors in M. gravidus.

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  The effects of Eisenia fetida (Lumbricidae) and vermicomposting on earthworm populations in Monteverde, Costa Rica, August 2008

  Sibylle Freiermuth

  Eisenia fetida (Lumbricidae) is an African earthworm species used in vermicomposting in the larger Monteverde region of Costa Rica. Despite its widespread use and growing popularity, little is known about the impact that introducing E. fetida has on local earthworm species. Exotic earthworms have the potential to drastically change the soil composition and community structure causing cascading effects throughout the ecosystem. However, previous studies have found signs of possible niche partitioning and that species richness and abundance actually increased in the presence of E. fetida. Taking samples for six farms using vermicomposting and six without, I found that vermicomposting actually increased the species richness of earthworm communities when considering all samples collectively (H’= 1.09, 0.78, t = 2.30, df = 267, P < 0.05 ), when only considering non-coffee farms (H’ = 0.78, 0.39, t = 2.13, df = 60, P < 0.05), and when comparing non-coffee farms to coffee-farms (H’ = 1.05, 0.70, t = 2.28, df = 114, P < 0.05). However, when looking at other subsets only including farms having applied vermicompost within the last year, excluding farms using greenhouses, and only considering coffee plantations there was no significant difference in earthworm communities. Based on this study, it seems that although E. fetida is entering farm soils, there is no negative impact on preexisting earthworm populations.

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  The role of L-dopa in Mucuna fruits: a deterrent or a marker, August 2008

  Jeff Dale

  Agoutis (Dasyprocta punctata) are ubiquitous in Monteverde and are known dispersers of Mucuna urens seeds despite the high levels of L-dopa the seeds contain. I tested the effects of L-dopa added to pejibaye (Bactris gasipaes) on seed selection by D. punctata. I hypothesized that L-dopa acts more as a marker for agouti dispersal than a deterrent for insect predation. In five sites of known agouti activity, I placed three types of seeds (i.e. those with natural L-dopa, synthetic L-dopa, and with neither) in piles of ten approximately one meter apart. My primary data were sequences of seed removal patterns. However, the total number of seeds removed was also recorded. The results indicate randomness in term of the sequences of seed removal. However, total seed count data and comparison of first and second choice data showed a non-random pattern. Specifically, there is for seeds with L-dopa added, and there is a significant trend to removing the same seed type following the first. The latter two results demonstrated a tendency for habituation in agouti behavior. Based on the results, I hypothesized that the reason for habit formation was the L-dopa consumption. A more expansive study of sequence data that evaluates seeds eaten vs. seeds cached could serve to answer a lot of the questions left open by my analyses.

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  Water quality of streams in the region of Monteverde, Costa Rica, August 2008

  Shuhan He

  The region of Monteverde, Costa Rica is rapidly growing and the water quality is undoubtedly being affected. The Quebradas Rodriguez, Máquina, and Cambronero were sampled at three elevations to assess the water quality of the rivers according to the parameters used to calculate the Water Quality Index. Two additional parameters, depth and velocity, were also taken. The data showed that there is a positive correlation between dissolved oxygen and biochemical oxygen demand at the three rivers. There is also a negative correlation between total coliform of the aforementioned variables. A large increase in nitrates and turbidity as well as a decrease in dissolved oxygen in the Quebrada Cambronero was found immediately following the Productores de Monteverde hog farm yet no such changes were seen in the Quebrada Máquina, which ran by Monteverde’s main road, and which experienced different anthropogenic influences. This difference is evidence that the water contamination at the Cambronero was due to the hog farm inputs. The Quebrada Cambronero recovered to its normal values for nitrates and dissolved oxygen but not turbidity downstream. Stream ecology, however, may still be affected by this contaminated zone.

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  Wet season Macrofungi of the Caribbean slope in Monteverde, Costa Rica, August 2008

  Oliver Herbst and Aldis Kurmis

  Despite its small size, Costa Rica harbors high fungal diversity. Although very little is known about fungi, they are beneficial to humans in the medicinal field and are also known to be important recyclers of nutrients in ecosystems. Their importance in our lives justifies further research concerning fungal communities. The purpose of our study is to investigate the community composition and species richness in a lower montane rain forest on the Caribbean slope at Monteverde, Costa Rica. Between the range of 1550 m and 1850 m, we recorded abundance of different morphological forms, substrate types and also compared species richness to canopy coverage, elevation, and pH level. A total of 40 morphospecies were found, of which 50% were toadstools. Additionally, 55% were found growing on soil substrates. We found no substantial correlation between canopy cover and species richness. There was a statistically significant trend for lower species richness at higher elevations (Spearman Rank Test, Rho = -0.80, p = 0.03, n = 7), and a nearly significant trend for greater species richness with increasing pH levels (Spearman Rank Test, Rho = -0.70, p = 0.08, n = 7). We found that as distance between transects increased, there was a trend for lowered similarity in fungal species composition (Spearman Rank Test, Rho = 0.36, p = 0.11, n = 21). Variability in Caribbean slope fungal communities is most likely caused by differences in abiotic (e.g. temperature, soil pH, wind, light availability) and biotic factors. Different tree communities and/or volcanic conditions of the area may control these factors.

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  Wing damage in three nectar-feeding bat species (Glossophaginae) of lower montane wet forest in Costa Rica, August 2008

  Amanda Nosal

  Little is known about tropical bats and the damage that collects on their wing membranes over time. Likewise, it is not known whether species or gender differ in the number of scars and tears on wings. This study analyzed the wing damage of three nectar-feeding bats and found that while overall wing damage was not significantly different between gender and species, specific areas of the wing membrane were statistically different. Females generally had higher rates of wing damage to the dactylopatagium major than males (two-way ANOVA, F = 4.21, p = 0.04). Another significant difference involved pregnancy; pregnant females had a higher average number of scars on the plagiopatagium than non-pregnant females (two-way ANOVA, F = 4.21, p = 0.05). As a result of this study, it has become apparent that further research is needed to understand why and how these significant differences occur.

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  Alcohol content in fruit-feeding Lepidoptera: preferences and effects on flight time, pattern, and speed, May 2008

  Lena Gottesman

  Fruit-feeding Lepidoptera live and feed on rotting fruit and tree sap flows. Eating fermented food is expected to alter their flight behavior making them sluggish and thus more susceptible to predation (Young 1979). Rotting food sources have similar chemical compositions but in different proportions. Ethanol is present in rotting fruits and sap flows (Omura and Honda 2003) and is most likely the agent causing sluggish or groggy behavior (Young 1979). In this study, I examine preference of fruit feeding Caligo spp. (Nyphalidae: Brassolininae) on different baits of varying ethanol concentrations. Furthermore, I examine whether alcohol content and time spent feeding on fruit impacts potential for predation, measured here as flight time, distance and the sporadic nature of the flight. This study was performed using existing fruit feeding platform in a large butterfly garden in Monteverde, Costa Rica. Small amounts of guaro:water solutions were added to rotting fruits at 10, 20, 30 and 35% ethanol. Caligo spp. individuals in the garden were allowed to choose among seven feeding stations, including three with no treatments (just rotting fruit). Butterflies having fed for different amounts of time were poked to see if they would fly. I found that Caligos spp. showed no preference for alcohol content, feeding freely on all fruit platforms. Behavior was influence by alcohol, but sluggishness was a function of time spent feeding, rather than alcohol content. Flight speed slowed as feeding time increased, regardless of alcohol content, suggesting that negative effects of ethanol were a function of feeding time rather than alcohol content in the fruit. The butterflies that drank shorter times flew longer. Still, there were no significant flight impairments from ethanol intake meaning that butterflies are adapted to deal with and use ethanol to their benefit. This was suggested by the fact that there were no significant differences in flight speed even for those butterflies feeding for over 90 minutes. As the highest feeding times in this study were only slightly greater than an hour and a half, this may have been too little time to impair flight. Stupor is widely reported in Caligo spp. and individuals on feeders in the morning were lying on their sides and very sluggish. These observations suggest that eventually, with more prolonged feeding times, ethanol will negatively impact flight and thus make the butterflies more susceptible to predation.

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  Anti-herbivore defense trade-offs: a comparison of Passiflora capsularis, Passiflora helleri, and Passiflora sexflora (Passifloraceae), May 2008

  Sara M.L. Sirivanchai

  Plants in the Tropics must evolve strategies for combating high levels of herbivory with few available nutrients. This results in possible tradeoffs between chemical and structural defenses. Three species of tropical passion vines, Passiflora capsularis, Passiflora helleri, and Passiflora sexflora (Passifloraceae) were examined for possible tradeoffs in cyanide, leaf toughness, glands and pubescence as anti-herbivore defenses. One young and one old leaf were collected from ten individuals of each species and analyzed for cyanide concentration and leaf toughness. In addition, observations were made regarding habitat, pubescence and presence or absence of blade glands. From the results it is clear that each species analyzed has adapted different anti-herbivore defense strategies. Passiflora helleri (mean = 119.88 µg/g leaf, Std Err. ± 39.54) demonstrated markedly higher concentrations of cyanide production as well as blade gland than P. capsularis (mean = 24.04 µg/g leaf, Std Err. ± 18.15) and P. sexflora (mean = 0.05 µg/g leaf, Std Err. ± 0.006), which did not have blade glands (N = 59, t = 2.01, P = 0.05). Passiflora sexflora showed observably more pubescence than either of the other two species. And P. capsularis exhibited an observable tradeoff in the levels of cyanide produced in young versus old leaves (N = 8, F = 5.14, P = 0.04, DF = 1). All species were found in the understory along well cleared trails. These data suggest that the anti-herbivore defense strategies employed by Passiflora spp. are diverse and represent evolutionary tradeoffs between different defenses under similar selective pressures.

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  A study of social interactions and web dynamics in the spider Anelosimus sp., (Theriidae) in Monteverde, Costa Rica, May 2008

  Molly Tolins

  Sociality in spiders represents serious evolutionary drawbacks, yet persists in some 20 species. Sociality of an undescribed species of spider, Anelosimus sp. (Theriidae), was studied in Monteverde, Costa Rica. The social interactions that were considered were: prey capture, kin recognition and web dynamics. I observed prey capture, whether adults or juveniles were attacking, and how long it took to first contact the prey. Adults preferentially attacked larger prey, while juveniles preferentially attacked smaller prey (p = 0.001, 2 = 10.517, df = 1, n = 23). There was also a trend showing that spiders in multiple-spider webs contacted prey faster than those in single-spider webs (p = 0.09). These results suggest that an increase in efficiency and a sharing of the prey-capture burden act as mechanisms to help make social living beneficial. A second part of the study consisted of introducing foreign spiders, both juveniles and adults, to webs and recording the reaction. The introduced adults were almost always shown aggression, while introduced juveniles were never shown aggression. This suggests the presence of kin recognition, as foreigners were recognized; smaller juveniles were largely ignored, while large foreigners were attacked and chased off. Size could be the mechanism for determining when juveniles finally disperse from the natal web. Finally, I found a positive relation between web volume and number of spiders (p = 0.001) and number of smaller webs within 50 cm (p = 0.08). This indicates that the web must increase proportionally with each additional spider in a brood. My study suggests possible mechanisms for making social living beneficial despite the serious evolutionary drawbacks.

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  A survey of Coleopteran species richness, diversity and abundance in habitats along a disturbance gradient, May 2008

  Logan W. Stockwell

  Three microhabitats in La Cruz, Costa Rica were surveyed for Coleopteran species richness, diversity and abundance in primary forest, secondary forest and active pasture. Survey sites correlated with levels of disturbance, which were hypothesized to reflect the availability and diversity of natural resources. A total of 865 Coleopterans were collected. Of the collected samples, 125 morpho-species and 22 families were identified. Species richness, diversity and abundance were calculated to see if they correlated with levels of habitat disturbance. It was hypothesized that natural resource abundance and diversity would be associated with levels of habitat disturbance. Forested areas with less habitat disturbance ought to have a greater variety of available resources on account of microclimate diversity and would therefore be able to sustain a greater diversity of Coleopterans. Results indicated that morpho-species richness was highest in primary forest whereas Coleopteran family analysis showed that family richness was highest in secondary forest. Results validate a correlation between habitat disturbance and Coleopteran diversity.

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  Comparison of fruit removal in tropical tree species between forest and urban areas – Monteverde, Costa Rica, May 2008

  Dominic Derenge

  Tropical frugivorous birds are facing the effects of increased human land development. The conversion of forests to road and buildings interrupts the interaction forest trees and their frugivorous dispersers. This study uses the tree/frugivore mutualism to asses the effect proximity to human influences has upon a forest health. Measurements of the removal rates of Citharexylum costaricensis (Verbenaceae) fruits in a fragment near to the forest displayed significantly higher removal rates than in the urban fragment (Paired T-Test, T=0.996 df=15, p = 0.043, n =16). Separate trials with Solanum rugosum (Solanaceae) fruit displayed the same trend (Paired T-Tests, T = 0.695, df = 10, P = 0.404, n = 11 ). These results show that the human development influences near the urban fragment have a detrimental effect upon this important relationship, which in turn may lead to a loss of stability and biodiversity in urban forest fragments.

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  Differential response to vibration stimulus in Metabus gravidus (Araneidae) communities, May 2008

  John McLaughlin

  This study is an investigation on the effect of distance between neighboring spiders on the reaction to an artificially generated vibration stimulus. The study was conducted using a tuning fork at 320 Hz in order to generate a vibration intended to stimulate the spider web. Metabus gravidus individuals that were closer to the source of vibration (mean 9.5 ± 2.75 cm) tended to react by fleeing, and those farther from the source (mean 16.5 ± 4.8 cm) typically reacted by approaching. The spider closest to the source of vibration reacted by fleeing and approaching, while the neighboring spider exhibited no response more often than expected by chance (X2 = 28.4). Thus individuals who maintain a greater distance to near neighbors benefit by minimizing interfering vibrations from neighboring webs.

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  Dispersion patterns of the American Leaf Spot (Mycena citricolor) in Costa Rican coffee systems, May 2008

  Rebecca Spicer

  Coffee (Coffea arabica) is both economically and culturally important to Costa Rica; however it is also highly susceptible to invasion by pests and pathogens. One such fungal pathogen is the American Leaf Spot (Mycena citricolor). This fungus thrives in the same high-elevation, humid habitats that produce some of the highest quality coffee. Plants harboring the fungus in great loads typically experience defoliation and fruit loss. The dispersion patterns of M. citricolor were investigated in eight plots located in Cañitas, Costa Rica. The number of fungal spots present was recorded for a total of 200 coffee plants, and the dispersion patterns were described for each plot and for the area. When compared to the expected Poisson distribution, five plots exhibited a patchy distribution and three plots were random. Fungal dispersion across all plots was also patchy. The predominance of the patchy distribution is related to the life cycle of the fungus, whereas management practices likely account for deviation from this pattern.

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  Effect of sunlight intensity and canopy coverage on herbivory in Gunnera insignis (Gunneraceae), May 2008

  Carolyn Rivers

  Studies on the influence of sunlight on herbivory have generally revealed that increased amounts of leaf damage occur in cool, shaded habitats. This study investigates the effects of both sunlight and canopy coverage on herbivore damage in Gunnera insignis by the undescribed beetle Macrohaltica sp. (Coleoptera: Chrysomelidae). This beetle is thought to feed on G. insignis because it can obtain secondary metabolites that make it undesirable to predators. In this investigation, all 90 plants studied revealed herbivore damage, with 71% of plants showing evidence of herbivory on the majority of leaves. The highest levels of leaf damage occurred on plants in both high light and high shade habitats, while those in moderate sunlight conditions revealed reduced herbivore damage. Resource availability, nutritional quality, and plant defenses influenced by sunlight could account for the variation in leaf consumption on G. insignis. Because light environment influences a number of factors related to the survival of a plant, the effects of sunlight on herbivory are complex and require further investigation.

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  Emergence patterns and male polymorphism in the nonpollinating fig wasp Aepocerus sp. (Torymidae), May 2008

  Katelyn Burgess

  This study was designed to investigate a perceived male dimorphism in the nonpollinating fig wasp Aepocerus sp. (Torymidae), as well as to examine emergence schedules of males and females as well as of different male morphs. I collected 100 Ficus pertusa figs and preserved the wasps that emerged from each fig every day for five days. I counted the number of male and female Aepocerus sp. that emerged from each fig each day, and I measured body size and degree of wing patchiness in males to assess whether the species exhibits male dimorphism. I found that males tend to emerge earlier (avg = 3.02 ± 1.14 days, N = 528) than females (avg = 3.44 ± 1.18 days, N = 340)(t = -5.601, p < 0.001). Male body sizes ranged from 1.1 to 2.5 mm with an average of 1.764 mm ± 0.20 (N = 528) and followed a roughly normal distribution. Across all males, wing patchiness was positively correlated with body size (R2 = 0.541, p < 0.001, N = 528) and body size was negatively correlated with day of emergence (R2 = 0.066, p < 0.001, N = 528). I observed two male morphs, distinguished most clearly by the appearance of their abdomens (rather than by body size or wing patchiness, as previously believed). Males with opaque abdomens tended to be smaller (avg = 1.57 ± 0.02 mm, N = 78) than males with translucent abdomens (avg = 1.80 ± 0.05 mm, N = 450)(t = 8.847, p < 0.001) and also tended to emerge later (avg = 3.65 ± 1.32 days, N = 78) than males with translucent abdomens (avg = 2.91 ± 1.02 days, N = 450)(t = -5.834, p < 0.001). My results highlight the need for further study of Aepocerus sp. in order to understand developmental mechanisms for male morphs.

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  Evaluating Costa Rica’s program for environmental services payments in the Monteverde region, May 2008

  Nathaniel F. Meyer

  Costa Rica’s environmental services payments or “PSA” (“Pagos por servicios ambientales”) program was created to provide an economic incentive for landowners to conserve forest, thus compensating them for the ecosystem services their conservation activities provide. This study was conducted to evaluate the program’s performance twelve years after its inception. By interviewing 20 private landowners in the Monteverde region, I ask (1) whether certain demographic parameters or property size affect participation, (2) whether the government is effectively informing farmers of the PSA opportunity, (3) what obstacles are preventing potential participants from successfully obtaining contracts, and (4) whether the program is functioning as a viable economic alternative to land uses that degrade ecosystem services. It was found that occupation affected participation, but not education, whether landowners live or work on the property, or property size. Business people did not participate, while conservation organizations tended to, perhaps implying that PSA payments are not a very financially lucrative endeavor for individual landowners. This was supported by the fact that while most interviewees found the program helpful, most would probably be conserving their forest anyway. It was also evident that government agencies are not informing many landowners of the program and that the application requirements, specifically the deed requirement, are a significant barrier to participation. The government agencies involved should reevaluate their application requirements to create an application process easier to navigate for the average small landowner, and should also actively seek out local conservation organizations to facilitate awareness of the program. If these measures are to be worth it, though, the program must also be advertised aggressively as a good carbon offset project in order for it to provide PSA payments large enough to present conservation with PSAs as an economically viable use of private land.

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  Impacts of human activity on tropical soil quality in relation to future land productivity and biodiversity, May 2008

  Lauren Bolte

  The high rates of tropical forest clearing followed by intensive agriculture may significantly degrade the soil’s original nutrient content and chemical composition, reducing future productivity and future restoration efforts. Land use impacts were determined by collecting soil samples from four sites in San Luis, Costa Rica. Three areas presented different agricultural uses, and the fourth was an area of forest, comparatively untouched by human activity. To evaluate existing nutrient levels, six tests were conducted from three soil samples from each site: ph, N, P, K, Al and Fe. Trends were found in that the site with the heaviest land use experienced the most change in nutrient levels compared to the forest soil. The three different agricultural areas displayed differing results, even as they were all within the same farming community, no more than 15m from one another.

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  Implementing a native medicinal plant garden in Monteverde, Costa Rica, May 2008

  Cory Howes

  The importance of plants has played a powerful role for medicine throughout human history. Tribes in Costa Rica once practiced Shamanism with native flora, but European settlement in the 15th and 16th centuries brought disease, killing much of the aborigines. With their loss, vast amounts of information had been lost regarding what plants they used for medicine. By implementing a garden at the Estación Biológica Monteverde in Monteverde, Costa Rica, an educational tool is created to give students first hand knowledge of 30 native medicinal plants found in Costa Rica. A booklet on the 30 plants was developed to educate about the plant description, medicinal uses and preparation of the plant. It is hoped the garden will inspire students to learn about how to use plants for their health and well-being.

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  Influence of elevation, host species, and host size on the density of mistletoe, Phorodendron robustissmum (Viscaceae), May 2008

  Jessica Rochelle Price

  Phorodendron robustissmum is an aerial hemiparasitic plant, dispersed by birds, that parasitize their hosts by tapping into the host’s vascular tissue. This research examines the density of mistletoe, Phorodendron robustissmum (Viscaceae) as a function of host species, host size, and elevation. This study was conducted in the Monteverde region in Costa Rica from 880- 1480 m. Data were collected on host species, density of mistletoe on two host species, elevation, and the diameter at breast height. ANCOVA and ANVOA showed that only host tree size influenced the clump density of Phorodendron robustissmum. Three different host species, Sapium glandulosum, Sapium laurifolium, and Sapium macrocarpum (Euphorbiaceae) harbor Phorodendron robustissmum in the study area.

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  Microclimate conditions within the rolled leaves of Lepanthes helleri (Orchidaceae), May 2008

  Brian C. Jones

  Epiphytic orchids of the cloud forest experience wet conditions from the high input of mist, but also drying from the potentially desiccating conditions of wind and light. The ability to minimize water loss while still maintaining photosynthetic levels is pivotal in an individual’s survival. This study examined Lepanthes helleri and the role of leaf-curling as a mechanism to regulate microclimate conditions. Parameters measured included the size of the leaf and the width of its opened curl, relative humidity of the ambient environment, air and temperature inside and outside of the leaf. The relationships between the width of the leaf opening (“aperture”) and stomatal density, the percent of open stomata, and the presence of flowers, buds, or neither were tested. Air temperature and leaf height, when factored into a model testing significance, had the most impact on how open the leaf was (stepwise multiple regression; R2 adj = 0.18, P < 0.05, DF = 58 and n = 61). Specifically, as leaf height and aperture size increased, the inside temperature increased. There was a significant difference between the mean temperatures inside and outside the leaf (Paired t-test; t = 7.48, P < 0.0001, DF = 60, n = 61 for both) as well as a negative linear regression between aperture and stomatal density (F = 8.04, R2 adj = 0.12, P = 0.007, n = 52).