Monteverde Institute: Tropical Ecology and Conservation

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  A medicinal plant analysis in premontane wet/moist and premontane wet life zones in Monteverde, Costa Rica, September 2001

  Ryan Pjesky

  This study was completed in Monteverde, Costa Rica on the diversity of medicinal plants in: premontane wet/moist and premontane wet forest. The purpose of this study was to find overall plant diversity and medicinal plant diversity within these two forests. After finding medicinal plant diversity, a conservation value could then be applied for each life zone accordingly. This was done by surveying three, 10-meter square plots in both life zones. It was hypothesized that plant diversities would be different within the two life zones. This hypothesis was not supported: the two plant communities had similar richness (S), diversity (H'), and evenness (E) for overall plant diversity and medicinal plant diversity. On a family level, premontane wet/moist medicinal plant diversity had richness of 21 families, H' = 2.2, and E = 0.37. On a family level, premontane wet medicinal plant diversity resulted in a richness of 19 families, H' = 2.4, and E = 0.39. These results were also reflected on genera and species levels for medicinal plant diversity and overall plant diversity. One explanation for this equivalence of diversity is perhaps the two life zones sampled were successionally similar forests. Another explanation is that it is possible these two areas were actually the same life zone due lack of elevation differentiation. In order to allow for assurance in results and proper conservation values more studies need to be done, on a larger scale, with more exhaustive sampling.

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  Effects of climate on inflorescences of the aroid (Araceae) Xanthosoma sp. and visitation rates of their scarab beetle pollinators, Cyclocephala sp., September 2001

  Jeffrey LeBrun

  Spadices of many aroids (Araceae) go through a process known as "thermogenesis", manufacturing heat to attract scarab (Coleoptera) pollinators. In Monteverde, Puntarenas, Costa Rica, Xanthosoma undipes occurs in patches at 1550 meters elevation. Here they attract two scarabs that are thought to be the sole pollinators: Cyclocephala nigerrima and C. sexpunctata. Chances of successful pollination of Xanthosoma have been shown to increase drastically with higher visitation rates of scarabs. Previous studies in Monteverde found no relationship between the temperature of the spathe and beetle visitation (Craig 2001) though taller plants at lower altitudes have been shown to attract more beetles (Sica 1999). Here, I examine beetle visitation to Xanthosoma in more detail by examining plant dispersion, plant cover, spathe/spadix characteristics, and weather. In total I observed 231 beetles for a mean of 4.1 ± 5.2 per inflorescence. Sixty-two percent were C. nigerrima. A low recapture rate (4%) suggests wide ranging populations of both species. Visitation to inflorescences was greatest for plant under tree cover, with large spathe openings, and shorter, warmer spadices. In addition, warmer nights had higher rates of beetle visitation, resulting in more beetles per inflorescence. Therefore, beetle visitation to Xanthosoma is dependant upon a combination of plant cover, spathe/spadix morphology and weather. Microhabitat preferences, ability to find active inflorescences, and warmer temperatures suggest that X. undipes must accommodate to scarab behavior to insure visitation and pollination.

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  Effects of plant size and flower color on the reproductive success of Pleurothallis sanchoi (Orchidaceae), September 2001

  Sarah Strozinski

  Factors contributing to the reproductive success of Pleurothallis sanchoi were examined in relation to plant size and flower color. This particular orchid has plants of varying sizes as well as three color morphs including yellow, purple, and yellow with purple petals. First, the potential for reproductive success was deduced by measuring, on individuals in natural populations, leaf and flower number and how they are related to flower color. Second, the removal and deposition of pollinia on flowers of different colors was examined. It was found that larger plants generally had more flowers, although there appears to be an upper limit above which increased flower production no longer occurs. Yellow flowers tended to be on larger plants but they did not necessarily make more flowers. Pollinia removal was fastest for yellow flowers while pollina deposition did not differ significantly between the three flower colors. Although yellow individuals tend to be more abundant in this population and appear to have a slight reproductive advantage, the persistence of the two other color morphs suggests that they either compensate for reproductive disadvantages, or that flower color is environmentally determined.

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  Faunal changes in bromeliad tank communities as a result of throughfall pH changes, September 2001

  Clay Buchanan

  Throughfall in forests is known to increase pH as a result of many neutralizing components on the tree. The purpose of this study was to examine how the change in pH due to Throughfall, affected the faunal composition in bromeliad tank communities. A total of 46 bromeliad tanks were sampled, which contained 2300 protists in 18 morphospecies. No significant correlation was found between pH and height on the tree or pH and volume of the tank sample. A decrease in diversity was noticed with the increase in volume of water in the tanks corresponding to heavy rainfall caused by hurricane Michelle. Abundance and richness did not have a significant correlation with pH. The average pH was 6.29 (±0.706), while the average pH for precipitation in the Monteverde area is 4.88. The difference in pH values is a result of a large increase in rain to the region during the study and because of throughfall effects.

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  Long-billed hummingbird specificity to long corolla flowers, September 2001

  Laura Anne Kefauver

  Long-billed hummingbirds prefer long corolla flowers, although structurally they can readily visit short corollas (Feinsinger 1983; Mayzel 1997). This study examined how facultative long-billed hummingbird preferences are to corolla length as well as the role of interference competition. Red and orange plastic tubes of two sizes (short = 2 cm, long = 4 cm) were attached to the holes of eight hummingbird feeders to mimic short and long corollas. A total of 64 thirty-minute observations were made counting visits to "corollas" of different color and length, species, and competitive interactions were also noted. The color of the corolla did not influence the number of visits (ANOVA, p = 0.7531). However, the species and corolla length influenced the number of visits (ANOVA, p < 0.0001). Short-billed hummingbirds significantly preferred short corollas while long-billed hummingbirds attended both short and long corollas with equal frequency. Overall, the number of visits to the short corollas was greater than visitation to long corollas (ANOVA, p < 0.0001). The selectivity of long-billed hummingbirds on long corollas appears to be a facultative relationship that maybe also influenced by exploitative competition. Short-billed species may be emptying nectar from short corolla flowers more frequently. Other studies suggest that nectar concentration and excretion rates, not studied here, may also direct long-billed species toward long corolla flowers.

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  Niche partitioning of Monteverde warbler species based on differences in microhabitat and vertical stratification, September 2001

  Justin Pochman

  Two congeneric warbler species in Monteverde occupy similar niches and may be competing for resources. The Three-striped Warbler (Basileuterus tristriatus) and the Golden-crowned Warbler (B. culicivorus) are both forest interior species that glean and sally for insects within several meters of the ground. This study looks at foraging preferences in these two species in areas of overlap and non-overlap, which is particularly important in light of recent geographic shifts upslope by the Golden-crowned Warbler (Donnelly 1998; Pounds 1999). The results show that the Three-striped and the Goldencrowned Warbler significantly overlap in both altitude (between 1420 m and 1485 m) and in habitat. They each used different microhabitats with greater frequency - the Threestriped Warbler preferred to forage in leaves and among epiphytes while the Goldencrowned preferred to forage on branch interiors and on stems of bushes. When the species did not overlap, the Three-striped Warbler foraged at a mean height of 2.4 m and the Golden-crowned Warblers at a mean height of 2.8 m. They shifted these heights up and down respectively when they were found overlapping (Three-striped = 2.1 m, Goldencrowned = 3.3 m). When individuals were actually observed foraging in the same species flock, they continued to display these trends in mean foraging height (Three-striped = 2.8 m, Golden-crowned = 4.0 m). Therefore this study shows that based on microhabitat preferences and vertical stratification, these two species of warbler partition their niches.

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  Opilionids: Social behavior as a defense mechanism, September 2001

  Scott Rosenthal

  Four environments were created with varying populations of opilionids and experienced hourly mass disturbances to observe if there is a relationship between sex and tibia length in grouping in Monteverde, Costa Rica. The ratio of males to females was five to seven and a significant size difference in tibia among sexes was noticed (T-test male mean = 3.719mm; female mean = 3.382mm, P < 0.0001). Additionally males in groups were significantly larger while females showed no difference (male mean tibia length = 3.678mm (solitary), 3.741mm (group), T-test P = 0.0003; female mean = 3.383mm (solitary), 3.381 mm (group), T-test P = 0.9324). As the amount of disturbance increased, the group size would decrease. Yet the percent of return changed little among varying population sizes. Grouping among opilionids may be used to decrease predation. Their chemical defense will have a stronger effect and they may use individuals as barriers from predators with the competitively superior individuals occupying the center of the group.

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  The Aroid-scarab mutualism: Importance of floral temperature for scarab attraction and copulation, September 2001

  Lauren Silbert

  Inflorescences of Xanthosoma undipes (Araceae) thermoregulate, heating to temperatures ranging from 36ºC-46°C. Scarab beetles in the genus Cyclocephala spp. (Coleoptera: Scarabaeidae), the pollinators of X. undipes, arrive at the inflorescence during heat production and remain for a period of two days, copulating and feeding. In this study I tested the hypothesis that thermogenesis is a mechanism by which to encourage pollinator copulation. Using an experimental design in which beetles were mated under varying temperature conditions to test for an optimal copulating temperature, I expected highest mating frequency to correspond to maximum inflorescence temperature. No correlation was found between temperature and mating frequency, suggesting that heat production does not attract pollinators looking for mates. Alternate hypotheses to explain production of heat are then examined.

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  The effect of elevation on fungal community species richness and composition in Monteverde, Costa Rica, September 2001

  Valerie Johnson

  This study investigated the effect of elevation on the species richness of fungal populations on the Pacific slope of the Tilarán Mountains in Costa Rica. The hypothesis being that changes in abiotic factors caused by change in elevation would be more or less favorable to growth of fungal communities. There was a total of 103 morphospecies found in six elevational transects between 1575m and 1825m. Statistical analysis showed a negative correlation between species richness and elevation, and that there was a strong trend between species turnover and distance between transects. Although the negative correlation opposes the hypothesis, an explanation may be found when considering extreme weather conditions due to a recent temporal.

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  The effects of habitat structural complexity on bird species richness and composition, September 2001

  Alison Jane Duff

  With the increasing rate of human activities in tropical regions, it is imperative that we understand the effects of habitat change on biodiversity, and develop appropriate conservation methods. A general trend of increasing bird species richness with increasing habitat structural complexity has been observed by a number of ecologists. The purpose of this study was to test whether this relationship holds for cloud forest bird communities in structurally complex primary forest as compared with simpler secondary forestdominated by Conostegia oerstediana (Melastomataceae). I predicted a strong positive correlation between bird species richness and habitat structural complexity, and bird species compositional differences between plot types. My hypothesis was supported with a statistically non-significant trend of increasing bird species richness with increasing habitat structural complexity. I did not find significant differences in bird species composition between primary and secondary forest plots, although I did observe a number of bird species which were more common in primary forest plots and others which were more common in secondary forest plots.

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  Community structure of vascular epiphytes in a Costa Rican elfin forest, May 2001

  Duryea Delacroix

  Neotropical montane forests are characterized by their great abundance and high diversity of epiphytes. This study examines the distribution of epiphytic families in three zones of sixMeliosma vemicosa trees using single-rope climbing techniques to access the forest canopy. Nine-hundred ninety-seven vascular epiphytes from eight angiosperm families and division Pteridophyta occurred at the study site. Orchidaceae, Bromeliaceae, Araceae, Ericaceae, Piperaceae, and Gesneraceae were the most common angiosperm families. Pteridophytes accounted for 40% of the individuals present. Friedman's test for Shannon -Weiner index and Orchidaceae showed a significant Chi-squared value (X2 =8.4, and X2 =7.4) and tied p-value (p = 0.02, and p = 0.02). Mode of seed dispersal, type of growth form and structure, and methods of water absorption and storage are discussed as factors that affect vertical distribution of epiphytes. This study indicates relatively high epiphyte diversity at the family level, at a mid-elevation site in Costa Rica.

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  Density and feeding of Brachypelma mesomelas (Araneae: Theraphosidae) in a Costa Rican cloud forest, May 2001

  Nathan Damstra

  Brachypelma mesomelas is endemic to Costa Rica and found widely distributed from 500m to 2000m in elevation. Their relative densities in any given area may be due to limited prey availability, or lack of sufficient burrows sites. To determine whether or not prey availability was a limiting factor in actual density, prey availability was determined through sampling using pitfall traps. Prey availability was then compared to results of required prey density determined through feeding experiments. Available burrow density was determined and compared to actual B. mesomelas density to determine whether or not burrow availability was a limiting factor in density. Neither prey availability nor burrow availability were found to be limiting factors in actual B. mesomelas density. Test subjects were fed various prey types to determine if there was a significant trend in feeding rate or percent biomass of prey consumed by B. mesomelas. Both feeding rate as well as percent biomass of prey consumed were found to follow a trend based on prey type (although not significantly different). Prey of each type were observed to follow a trend of the rate at which they could be consumed, independent of size, based on high calculated R² values of slopes. Softer prey were able to be consumed faster and a greater percent of prey biomass consumed than were harder prey. Based on these results, it is concluded that energy-maximizing feeding occurs in B. mesomelas based on consistency of feeding rates of different prey types (i.e. energy is being maximized by limiting the amount of feeding time). Also, it is tentatively concluded based on observations in this study, that the limiting factor of B. mesomelas demonstrating optimal foraging traits is an inconsistent optimal prey source.

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  Determinants of morphological characteristics, thermogenetic heating and Scarabaeidae pollination in Xanthosoma robustum (Araceae), May 2001

  Joshua A. Craig

  Xanthosoma robustum (Araceae) relies upon thermogenic heating just after sunset to attract its mutualist Scarabidae pollinator. All morphological characteristics measured (number of leaves, leaf size, stalk height, spathe length, spadix length, and kettle diameter) were correlated; demonstrating larger plants have more leaves, larger leaves, taller stalk heights, taller spathes, taller spadices and wider kettles. However, no measured characteristic was found to influence Scarabaeidae visitation. Maximum temperature of an inflorescence was found to be positively correlated with leaf size and negatively correlated with spadex height (t-test p-values 0.0007 and 0.0150, respectively). However, no recorded temperature measurements were found to influence Scarabidae visitation.

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  Nesting behavior of the female and male resplendent quetzal (Pharomachrus mocinno), May 2001

  Jennifer Heller

  Knowledge of nesting behaviors of tropical birds, even for the magnificent Resplendent Quetzal, comes from few records of observations outside the nest. However, the popularity of the bird in the Monteverde Cloud Forest Preserve inspired the Tropical Science Center to place a camera inside one of the box nests just before the 2000 nesting season. I studied the images taken during the entire nesting period. Upon analysis of the data, I found that parental care and behavior changed significantly as the chick aged. Additionally, only females slept in the nest, and although both the male and female brooded and attended to the young, the female spent significantly more time in the nest than the male (p < 0.05). As the chick aged, the time that the parents spent in the nest decreased significantly (p < 0.0001). Observations recorded by others from outside the nest concur with this data. Nest predation is high in tropical environments; thus, having both parents alternating care in the nest may increase the chances of a successful brood. However, in my study of the quetzal, the duties were not necessarily equally shared, leaving the female more vulnerable to predation.

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  Species richness and composition in understory moss communities in lower montane rain forest in Monteverde, Costa Rica, May 2001

  Erika Carls

  This study investigated the difference in species richness and composition of mosses in primary lower montane rain forests, forest gaps and forest-pasture edges, as well as among different substrates. Mosses in Monteverde, Costa Rica were collected for equal amounts of time from rotting logs, tree trunks and leaves in all habitat types, and separated morphologically. Overall morphological species richness is 39 for primary forests, 38 for gaps and 28 for edges. Species richness is 26 to 22 for logs, 22 to 20 for trees and seven to zero for leaves. Moss epiphyll communities are very dissimilar (Sorenson's qualitative index 0.1 - 0.2) from all other substrates. No epiphylls were observed in edges, probably because edge conditions are hotter, drier and windier. This suggests that moss epiphyllsmay make good bioindicators of forest health. The low species richness of epiphylls could be explained by a random walk to monodominance or by inferior growth conditions of leaves.

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  Territoriality and courtship behavior in male Anartia fatima (Nymphalinae), May 2001

  Frazier Cristianne

  Chasing behavior in butterflies may be the result of territorial defense or simply the result of mate location. Such aggressive behavior is frequently observed in male Anartia fatima. It was hypothesized that older male Anartia fatima would be more aggressive than younger males, who have less to lose if they do not defend access to females. Behavioral observations were made on 38 males. Multiple regressions were run to see how age and ambient conditions affected the behavior of the males. Older males were found to be more aggressive and spend more time in courtship, but it could not be concluded that the aggressive behavior in Anartia fatima was ultimately a result of the need to defend a territory to gain access to females. It is more likely that "aggressive" behavior is actually chasing as part of mate location and courtship behavior. Any benefits a male receives from being inherently "aggressive" as a result of the demands of courtship are secondary. Temperature was the abiotic condition factor to exhibit the most significant impact on the behavior of males. Increasing temperatures tended to result in an increase in the amount of time a male spent off of his perch and an increase in the maximum distance between perches.

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  The effect of elevation and location on the fitness of Heliconiaceae monteverdensis (Heliconiaceae), May 2001

  Katherine Long

  Heliconia monteverdensis is a species of Heliconiaceae that is endemic to the Monteverde cloud forestof Costa Rica. A limited amount of research has been conducted concerning H. monteverdensis, therefore, little is known about its life history. In this study, simple observations are reported with regards to its distribution, physical characteristics and interactions with its community. The effect of location and elevation on the fitness, (the ability of the plant to survive and reproduce), of H. monteverdensis was also studied. The three locations compared were the Atlantic slope, the Pacific slope and the Ridge in between the two slopes. Five parameters were then used to measure fitness; leaf size and number of flowers, bracts, leaves, and fruits. Elevation and location are found to have significant effects on fitness levels of H. monteverdensis, with the plants on the Ridge and at higher elevations sustaining greater fitness. The climate change in Monteverde and its possible effect on H. monteverdensis fitness was also studied. It was hypothesized that the increase in temperature and dryness due to climate change would decrease H, monteverdensis fitness levels. However, this study suggests that changes in moisture and temperature will not significantly decrease fitness levels of H. monteverdensis. However, other indirect effects that climate change might have on H. monteverdensis are discussed. The purposes of this study were to develop an understanding of the life history of H. monteverdensis and to study the effect of elevation and location on its fitness levels. With this knowledge, the possible affects that the changing climate of Monteverde will have on the future of H. monteverdensis could then be suggested.

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  The effects of spatial distribution on the proportion of pollinia removed in Epidendrum radicans (Orchidaceae), May 2001

  Jennifer Woo

  Many plants that do not offer rewards for pollination are involved in a floral mimicry. Mimic flowers copy visual cues from unrelated model species that offer rewards and rely on the chance visitation by confused pollinators. Epidendrum radicans is a mimic plant that strongly resembles two plants that provide rewards: Asclepias curassavica (Asclepiadaceae) and Lantana camara (Verbenaceae). This study examines how spatial distributions affect the proportion of pollinia removed (PPR) for the non-rewarding mimic Epidendrum radicans. Nearest neighbor distances between infloresencces, total number of flowers, and total number of pollinia removed were recorded at thirty patches of E. radicans in Monteverde, Costa Rica. A wide range of patch densities was found along with a negative relationship between proportions of pollinia removed (PPR) and density. Extremely large patches of E. radicans did not follow the negative trend between PPR and density. This could be due to multiple visits from naive pollinators who have not realized that no reward is offered or the possibility of multiple visits by pollinators who are reassuring themselves of the non-rewarding characteristic. A patchiness index was also calculated for each patch. However, no conclusions could be made about the relationship of proportion of pollinia removed (PPR) and the index of patchiness. Although E. radicans is involved in a floral mimicry, the data did not suggest that the mimic grows in close proximity to its models.

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  The relationship between mist exposure and reproductive success in Scaphyglottis acostaei (Orchidaceae), May 2001

  Rebecca Lara

  I examined how the reproduction and fitness of the orchid, Scaphyglottis acostaei depends on the water resources derived from cloud mist in Monteverde, Costa Rica. Thirty-six individuals of S. acostaei were selected to undergo treatments of mist exclusion, mist enhancement and light modification for 15 days. The pseudobulb width changed significantly over the 15 days for the four treatments, suggesting that mist precipitation is a limiting resource for S. acostaei. Additionally, mist was collected on the northeast and southwest sides of four pasture trees, and a total of 139 individual orchids were sampled for number of fruits, racemes and leaves, and leaf length. I found a higher reproductive success of S. acostaei on the northeast sides of the sample trees, which is partially explained by the trend that those individuals were also exposed to a higher more frequent amount of mist than individuals on the southwest sides. My findings suggest that even orchids with specialized mechanisms for coping with water limitation are sensitive to changes in mist frequency.

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  Trail clearing and foraging behaviors in two species of leaf cutter ants (Atta cephalotes and Acromyrmex coronatus), May 2001

  Katy Zaksek

  Leaf cutting ants play an integral role in tropical forest communities. Foraging strategies impact the harvest efficiency of a colony and in turn rates of herbivory on a forest community. Trail construction and foraging efficiency were compared between two species of leaf cutting ants (Atta cephalotes and Acromyrmex coronatus). Atta cephalotes constructed major trail systems and Acromyrmex coronatus, a species with smaller colony size, traveled between harvest sites on simple foraging lines across leaf litter. Significant differences existed across species with respect to traveling speed and burden ratios (ANOVA, p < 0.0001 and 0.0071, respectively) indicating benefits in maintaining unobstructed trails. Atta cephalotes trail clearing behaviors were investigated further by simulating natural obstructions. Colonies exhibited rapid removal of all objects placed on trails and removal time was significantly correlated with worker activity and distance from nest entrance (ANOVA, p = 0.0016 and 0.0163). This study attempts to demonstrate that A. cephalotes gains a competitive advantage over other leaf-cutting species, and reaps benefits, from trail construction and maintenance despite large initial investment.

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  Acidic environments within tank bromeliads and its effect on microorganism community richness, November 2000

  Jennifer Wade

  Elfin forest tank bromeliads were shown to have lower pH when positioned below mats of epiphytic bryophyte than in open gaps. The effect of lower pH was studied to see if it influenced microorganism community abundance, species richness, evenness and diversity. It was found that increasing levels of pH over a range of 4.3 – 5.8, increased population sizes of most microorganisms. In fact abundance of individuals in the entire community spanned over an order of magnitude (82- 1936 individuals). Species richness also increased with pH but only as a function of increased abundance of individuals. One species richness was corrected for differences in abundance; the pattern of increasing species richness with pH was lost. It is possible that acidic environments limit productivity which would in turn reduce population sizes due to a limited resource base. Both diversity and evenness had no correlation with pH. Corrected species richness was also determined to be lower in those bromeliads with moss cover than those of open gaps. This could be attributed to moss bromeliads being more stable due to their protective location under the canopy, which results in a lower species richness by virtue of the Intermediate Disturbance Hypothesis.

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  A comparison of ground-dwelling insect communities in gaps and closed canopy forest in the elfin forest of Monteverde, Costa Rica, November 2000

  Elizabeth Green

  This experiment compared communities of ground-dwelling insects in gaps and closed canopy forest in the elfin forest of the Estación Biológica Monteverde in Puntarenas, Costa Rica. Insects were trapped with pitfall traps in six gaps and adjacent forest areas in October and November 2000. Shannon-Weiner Diversity indices, Margalef species richness indices, evenness (H’ /(In S)), mean abundance per site, and Morisita Similarity indices were compared. Diversity differed only for Coleopterans, which were more diverse in gaps (H’ = 1.201) than in forest (H’ = 0.8387; modified t-test t= 1.979, p < 0.001). The Margalef index of species richness did not vary between paired gap and forest sites for total insects captured, but was significantly higher for Coleopterans in the gaps than in the forest (sign test, a level 0.05). Coleopterans also had greater evenness in gaps than in forest (sign test, a level 0.05). Mean abundances in gap (8.04 +/- 7.669 mean number of insects/trap) and forest (5.09 +/- 3.191 insects/trap) sites were not different. The Morisita Similarity index was 0.4846, with 47.05% of ground-dwelling insect morphospecies shared between gaps and closed forest. Perhaps conditions in gaps and closed canopy areas in this forest are sufficiently different to allow specialization by ground-dwelling insects to one or the other habitat type.

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  Adaptive response of Scaphyglottis acostaei (Orchidaceae) to microhabitat variability, November 2000

  Andrew Fisher

  Orchids exhibit many adaptations, including pseudobulbs which store water and root velamen, which assists in water uptake, to deal with the harsh, water stressed conditions that are an integral part of epiphytic life. Within a single host tree the intensity of water stress varies between microhabitats caused by presence of moss and bark fissures to reduce evaporation of water, and positions that increase or decrease exposure to wind, precipitation and sun. The orchid, Scaphyglottis acostaei exhibits variable pseudobulb sizes and water holding potential of velamen, possibly as a result of different levels of water stress and water availability. In this study I compared water holding capacity of the velamen and average size of pseudobulbs between individuals in different microhabitats. It was found that the presence of moss was associated with an increase in the water holding potential of velamen and decreased the average size of pseudobulbs. There was a positive correlation between the dry weight of velamen and the amount of water it can hold, indicating a increased production of velamen with greater water ability. This increase in velamen production could be a result of the potential to absorb more water in areas where it is more available. The decrease in pseudobulb size when water is more abundant is attributed to the reduced need for storing water.

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  Ant diversity between two methods of coffee farming in the San Luis Valley, November 2000

  JoAnna Leachman

  Due to herbaceous, fungal, or insectivorous pests, coffee farms are sometimes treated with chemicals throughout the year to eliminate these problems. However, this can impact beneficial insects, like predaceous ants. Using tuna and honey as bait, I captured ants on the ground of three organic and three inorganic coffee farms. I also measured the amount of ground vegetation at each site. I found a significantly higher diversity of both total and predaceous ant species on organic farms (p < 0.001, p <0.005). The amount of ground vegetation on organic farms was also significantly higher (p < 0.0001).