Apparent survival of tropical birds in a wet,premontane forest in Costa Rica

Despite the importance of tropical birds in the development of life history theory, we lack information about demographic rates and drivers of population dynamics for most species. We used a 7‐year (2007–2013) capture‐mark‐recapture dataset from an exceptionally wet premontane forest at mid‐elevation in Costa Rica to estimate apparent survival for seven species of tropical passerines. For four of these species, we provide the first published demographic parameters. Recapture probabilities ranged from 0.21 to 0.53, and annual estimates of apparent survival varied from 0.23 to 1.00. We also assessed the consequences of inter‐annual variation in rainfall on demographic rates. Our results are consistent with inter‐annual rainfall increasing estimates of apparent survival for two species and decreasing estimates for three species. For the three species where we could compare our estimates of apparent survival to estimates from drier regions, our estimates were not consistently higher or lower than those published previously. The temporal and spatial variability in demographic rates we document within and among species highlights the difficulties of generalizing life history characteristics across broad biogeographic gradients. Most importantly, this work emphasizes the context‐specific role of precipitation in shaping tropical avian demographic rates and underscores the need for mechanistic studies of environmental drivers of tropical life histories.     

Phenological behavior of the tree Elaeagia uxpanapensis (Rubiaceae), in a premontane rain forest of Costa Rica

Phenology of the tree Elaeagia uxpanapensis was studied from March 1994 to March 1998. This species is a canopy emergent in the A.M. Brenes Biological Reserve, Alajuela, Costa Rica. Fifteen mature trees were marked in order of appearance and observed every month using bionculars. A platform was built on one three better distinguished the transition from flowering to fruiting. Leaf abscission and budding were continuous throughout the year with several peaks, while flowering and fruit production occurred every 28 and 25 months, respectively. Leaf-fall was positively correlated with a ir temperature (n = 13, r = 0.44, p < 0.05), and fruiting with precipitation (n = 13, r = 0.37, p < 0.05) and relative humidity (n = 13, r = 0.44, p < 0.05). Bud formation was in inversely associated with precipitation (n = 13, r = 0.66 p < 0.05) and relative humidity ( n = 13, r = 0.61, p < 0.05).     

Inter-annual higher germination from smaller than medium-sized premontane wet forest fragments for an animal-dispersed tree species in Costa Rica

Forest fragmentation is pervasive in tropical landscapes, and animal-dispersed tree species are among the most threatened. Seed source is an important factor for active conservation and restoration efforts for such species but many studies show lower germination levels for seeds collected from small fragments compared to larger forests. However, the increasing rarity of large forests makes them difficult to be used as practical seed sources. We assessed the potential of small to medium-sized fragments (19–209 ha) to serve as seed sources for the conservation and restoration of an animal-dispersed tree Lacistema aggregatum (Lacistemataceae) in Costa Rican premontane wet forests. Germination, seedling survivorship, and growth for 2 years were quantified in a screen house environment. Two years later, more rigorous germination tests were conducted. Germination levels differed substantially among source trees. Seeds from some individuals had no germination inter-annually, suggesting that fecundity alone may be an incomplete indicator of individual fitness. Furthermore, in contrast to many previous studies, germination was better for seeds from smaller fragments for both study years. Subsequent seedling survivorship did not counteract the trends generated by germination, and the better performance of seeds from smaller fragments was retained for 2 years as ex situ seedlings. Higher seed quality in smaller fragments was associated with larger seed size in trees near forest edges, which might result from higher potential outcrossing rates. Our results suggest a previously unrecognized potential of small fragments as seed sources.     

Genetic demography of Antioquia (Colombia) and the Central Valley of Costa Rica

We report a comparative genetic characterization of two population isolates with parallel demographic histories: the Central Valley of Costa Rica (CVCR) and Antioquia (in northwest Colombia). The analysis of mtDNA, Y-chromosome and autosomal polymorphisms shows that Antioquia and the CVCR are genetically very similar, indicating that closely related parental populations founded these two isolates. In both populations, the male ancestry is predominantly European, whereas the female ancestry is mostly Amerind. In agreement with their isolation, the Amerindian mtDNA diversity of Antioquia and the CVCR is typical of ethnically-defined native populations and is markedly lower than in other Latin American populations. A comparison of linkage disequilibrium (LD) at 18 marker pairs in Antioquia and the CVCR shows that markers in LD in both populations are located at short genetic distances (相似文献   

Rare hemoglobinopathies in Costa Rica]

Among the rare hemoglobinopathies found in Cost Rica are those of the Alfa, Beta, and Delta chains. Among these, Hb Cubujuquí, an undescribed variant, is of special interest. There was an association between the different thalassemic syndromes and their combinations with abnormal hemoglobins.     

Seed dynamics during forest succession in Costa Rica

Soil seed banks and current seed inputs each play a role in tropical succession. We compared the abundance and floristic composition of seeds from these two sources at a Costa Rican site by germinating seeds from the soil, measuring seed inputs for 3 yr, and monitoring the earliest colonists in a forest clearing.There were an estimated 6800 viable seeds/m² in the soil of 3.3-yr-old vegetation, 9500 seeds/m² in 11-yr-old vegetation, and 7000 seeds/m² in a 75-yr-old forest. An estimated 10100 seeds/m² fell on the soil surface of the young successional vegetation during 3 yr and 3700 seeds/m² fell during that same time in the forest.Locally produced seeds accounted for about 75% of the seed input to the soil surface early in succession. Seeds dispersed out of young successional vegetation increased the quantity and species richness of the seed input and storage in an adjacent forest. Much of the species richness of the young successional vegetation resulted from seeds dispersed there from other communities by animals.Deforestation stimulated germination of most seeds in the surface soil of the old forest, including seeds of the dominant canopy tree. The recruitment of seedlings from the soil seed bank numerically overwhelmed that from post-disturbance seed rain and sprouts.We evaluated patterns of soil seed storage during succession and predicted the ability of vegetation of differing ages to respond to disturbance. Immediately after disturbance the number of seeds in the soil plummeted due to mortality, low inputs, and germination. As the vegetation regrew, the soil seed bank increased to a peak after 4 to 7 yr, then gradually decreased to its pre-disturbance size. High-frequency pulses of disturbance should result in reduced species richness, dominance by species with long-lived seeds, and fast recovery by seedling recruitment from the soil seed bank.Journal series number 6459 from the Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida 32611, USA.Reprint requests to J. J. E. at Florida.     

Genetic variants of the lipoprotein lipase gene and myocardial infarction in the Central Valley of Costa Rica

To assess common variants of the LPL gene that could influence susceptibility to myocardial infarction (MI), we assessed three functional single-nucleotide polymorphisms (SNPs), D9N, N291S, and S447X, in 1,321 survivors of a first acute MI and 1,321 population-based controls, matched for age, gender, and area of residence, all living in the Central Valley of Costa Rica. Conditional logistic regression was used to estimate odds ratio (OR) and 95% confidence interval (CI). The frequency of the X447 mutant allele was significantly lower in cases than in controls (6.2% vs. 7.6%; P < 0.01), whereas no association with MI was found for D9N or N291S. The OR (95% CI) for carriers vs. noncarriers of the X447 allele was 0.80 (0.63-1.01); when considering the haplotype that contained X447 and normal alleles of D9N and N291S, the OR (95% CI) was 0.66 (0.48-0.91). Twelve other SNPs were assessed in a subgroup of the population, of which the four functional SNPs were found to be monomorphic, and no correlation with MI was observed for the other eight neutral SNPs. The X447 mutant allele of the LPL gene may protect from MI risk, although this effect is small.     

The structure and phenology of a moist deciduous forest in the Central Indian Highlands

The vegetation structure and phenology of a 74.5 ha block of moist deeiduous forest in Kanha Tiger Reserve, Madhya Pradesh, India were investigated during primatological fieldwork. Within a grid of 0.25 ha quadrats all 9935 trees (woody plants > 2 m tall), of 63 species, were enumerated and their girth measured. The forest was dominated by the dipterocarp sal (Shorea robusta). Most species were rare and showed clumped distributions within the sea of sal whilst the dispersion of five large canopy trees could not be distinguished from random.The phenology of 215 trees, of 61 species, was monitored over 14 months using an index of phytophase abundance. Leaf renewal was highly synchronous between and within species, mostly occurring between February and June. One species was evergreen, 5 were semi-evergreen and 55 were deciduous. Flowering generally occurred between leaf fall and flush whilst fruiting peaked late in the hot weather and early monsoon.     

Microclimatic parameters influencing nitrogen fixation in the phyllosphere in a Costa Rican premontane rain forest

The acetylene reduction method was used to measure nitrogen fixation in the phyllosphere of attached leaves of different phorophytes under natural conditions in a premontane rain forest in Costa Rica. Maximum rates of nitrogen fixation (26 ng N · cm⁻² leaf area · h⁻¹) – mainly due to the activity of two species of Scytonema (Cyanobacteria) – were measured in the rainy season in bright sunlight. Rates of nitrogen fixation were correlated with the leaf area covered by Scytonema. In periods without precipitation the fixation activity decreased to zero within 2–3 days. As long as the epiphylls were sufficiently supplied with water, other microclimatic factors like temperature and light intensity also influenced nitrogen fixation rates, but to a lesser extent. Relative humidity and species of phorophyte showed no direct influence. It was concluded that the most important factor for nitrogen fixation in the phyllosphere was the availability of liquid water. Linking these results to meteorological data, the input of nitrogen by biological nitrogen fixation in the phyllosphere in the investigation area was estimated to be as much as 1.6 ± 0.8 kg N · ha⁻¹ · year⁻¹ per unit of leaf area index (LAI). For an LAI of 2 for the understory the nitrogen input would vary between 2 and 5 kg N · ha⁻¹ · year⁻¹. This work also demonstrates the importance of detailed knowledge of variation in microclimate throughout the year as a basis for extrapolation of the annual nitrogen input. Received: 21 December 1997 / Accepted: 14 June 1998     

First isolation of Clostridium tetani from soils of Meseta Central, Costa Rica]

Clinical evidence has long pointed to the existence of Clostridium tetani in Costa Rica. Thirty soil samples were studied for clostridia, and two yielded six strains of C. tetani, four of which proved to be toxigenic when mice were inoculated intraperitoneally with the culture supernates. These four isolates could be neutralized when their toxic supernates were admixed with tetanus antitoxin.     

The occurrence of Frankia in tropical forest soils of Costa Rica

Infective and effective Frankia were shown to occur in five diverse tropical forest soils of Costa Rica. Results of a plant infection assay indicated that Frankia is a common component of the soil biota in low and high elevation, primary and secondary forest soils. This is the first report of Frankia in lowland tropical rainforests of the Americas. These results suggest either a nonsymbiotic population of soil Frankia, the presence of unknown actinorhizal host species, or an ability of Frankia to be dispersed over long distances.     

West African and Amerindian ancestry and risk of myocardial infarction and metabolic syndrome in the Central Valley population of Costa Rica

Genetic ancestry and environmental factors may contribute to the ethnic differences in risk of coronary heart disease (CHD), metabolic syndrome (MS) or its individual components. The population of the Central Valley of Costa Rica offers a unique opportunity to assess the role of genetic ancestry in these chronic diseases because it derived from the admixture of a relatively small number of founders of Southern European, Amerindian, and West African origin. We aimed to determine whether genetic ancestry is associated with risk of myocardial infarction (MI), MS and its individual components in the Central Valley of Costa Rica. We genotyped 39 ancestral informative markers in cases (n = 1,998) with a first non-fatal acute MI and population-based controls (n = 1,998) matched for age, sex, and area of residence, to estimate individual ancestry proportions. Odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated using conditional (MI) and unconditional (MS and its components) logistic regression adjusting for relevant confounders. Mean individual ancestry proportions in cases and controls were 57.5 versus 57.8% for the Southern European, 38.4 versus 38.3% for the Amerindian and 4.1 versus 3.8% for the West African ancestry. Compared with Southern European ancestry, each 10% increase in West African ancestry was associated with a 29% increase in MI, OR (95% CI) = 1.29 (1.07, 1.56), and with a 30% increase on the risk of hypertension, OR (95% CI) = 1.30 (1.00, 1.70). Each 10% increase in Amerindian ancestry was associated with a 14% increase on the risk of MS, OR (95% CI) = 1.14 (1.00, 1.30), and 20% increase on the risk of impaired fasting glucose, OR (95% CI) = 1.20 (1.01, 1.42). These results show that the high variability of admixture proportions in the Central Valley population offers a unique opportunity to uncover the genetic basis of ethnic differences on the risk of disease.     

Floristic composition across a climatic gradient in a neotropical lowland forest

Abstract. This study deals with the floristic composition of lowland tropical forest in the watershed of the Panama Canal. The floristic composition of large trees in 54 forest plots was analysed with respect to environmental factors, including precipitation, geologic parent material, stand age, topography, and soils. The plots contain 824 species of trees with a diameter at breast height ≥10 cm and represent a regional flora with exceptional β‐diversity. Plot data indicate that the Panamanian forest is strongly spatially structured at the landscape scale with floristic similarity decreasing rapidly as a function of inter‐plot geographic distance, especially for distances <5 km. The ordinations and patterns of endemism across the study area indicate broad floristic associations well correlated with Holdridge life zones. The results indicate the positive aspects of life zone classification at regional scales, while simultaneously highlighting its inadequacy for finer scales of analysis and resource management. Multivariate gradient analysis techniques (Non‐metric Multidimensional Distance Scaling and Detrended Correspondence Analysis) show clear patterns of floristic variability correlated with regional precipitation trends, surficial geology, and local soil attributes. Geologic and edaphic conditions, such as acidic soils or excessively drained limestone substrates, appear to override the effects of precipitation and modify forest composition. We conclude that the Panamanian forest shows clear patterns of spatial organization along environmental gradients, predominantly precipitation. The rapid decline in floristic similarity with distance between stands also suggests a role for dispersal limitation and stochastic events.     

High litterfall in old-growth and secondary upper montane forest of Costa Rica

Tropical upper montane forests usually comprise trees of small stature with a relatively low aboveground productivity. In contrast to this rule, in the Cordillera de Talamanca (Costa Rica), tall trees (>35 m in height and more than 60 cm in diameter) are characteristic for the upper montane old-growth oak forests which are growing at an altitude of almost 3,000 m close to the alpine timberline. For these exceptional forests, productivity data are not yet available. In this study, we analyzed litterfall and its components (tree leaves, litter of epiphytic vascular and non-vascular plants, mistletoes, twigs and other canopy debris) in three forest stands belonging to different successional stages and related seasonal changes in litterfall to micrometeorological variables. The studied stands were early-successional forest (10–15-year-old), mid-successional forest (40-year-old), and old-growth forest. The stands are dominated by Quercus copeyensis and are located at 2,900-m altitude. Total litterfall was highest in the mid-successional forest (1,720 g m⁻² y⁻¹), and reached 1,288 g m⁻² y⁻¹ in the old-growth forest and 934 g m⁻² y⁻¹ in the early-successional forest. Litter mass was dominated by leaves in all stages (56–84% of total litterfall). In the old-growth forest, however, twigs and small canopy debris particles (33%), epiphytes (6%), and mistletoes (5%) also contributed substantially to litter mass. Leaf litterfall showed a clear seasonal pattern with a negative correlation to monthly precipitation and highest values in the dry season (January–April). However, the strongest correlation existed with minimum air temperature (negative), probably because temperatures already dropped at the end of the rainy season, when precipitation had not yet declined and leaf shedding already increased. In contrast, litterfall of epiphyte mass, and twigs and other debris was mostly dependent on occasional strong winds. We conclude that the upper montane oak forests of the Cordillera de Talamanca are exceptional with respect to the large tree size and the relatively high productivity as indicated by litterfall. Litter mass was especially high in the mid-successional and old-growth forests, where the observed annual totals are among the highest recorded for tropical forests so far.     

Vegetation effects on microclimate in lowland tropical forest in Costa Rica

The temperature and atmospheric humidity in a tropical lowland rain forest in Costa Rica were measured in order to assess the microclimate in different forest environments. Two disturbed sites, a single tree fall gap (400 m²) and an 0.5 hectare clearing, were compared for periods up to two years after disturbance. Two locations in primary forest, the canopy and understory, were also monitored. Temperatures were highest in the clearing, intermediate in the canopy and gap which were similar, and lowest in the understory. Vapor pressure deficits (VPD) were highest in the clearing, followed by the canopy, the gap and the understory. With regrowth of the vegetation in the gap and clearing sites, the temperatures and vapor pressure deficits significantly decreased. After 1 year, the microclimate at seedling height in the clearing resembled that of the gap, and after two years the microclimate of the gap was very similar to that of the understory. Seasonal differences in temperature and VPD were small compared to differences caused by changes in the stature of the vegetation.     

Tectonic survey of the Central Pacific coast of Costa Rica

Three fossil coral samples (Pocillopora elegans and Pocillopora damicornis) were collected from a beachrock in Puerto Escondido, central Pacific coast of Costa Rica. The age of the samples ranged from 1272+/-60 to 2010+/-60 years BP. They represent some of the few Holocene fossil corals known from the Pacific coast of the Americas. The uplift rate for the central Pacific coast of Costa Rica was calculated in 0.4 to 2.1 mm year(-1).     

Structure and floristics of secondary and old-growth forest stands in lowland Costa Rica

We characterized stand structure and floristic composition of woody life forms in three, 16–18 yr old secondary stands that regenerated after pasture abandonment, and three nearby old-growth stands of tropical rain forest in lowland Costa Rica. Basal area and stem density for each of four plant size classes (seedlings, saplings, treelets, trees) were similar among stand types, but density of adult canopy palms (individuals 10 cm DBH), was lower in the secondary stands. We estimate that 15% of the basal area of stems 10 cm DBH correspond to remnant trees in our secondary stands. The observed rapid woody regrowth compared to other published studies in the lowland neotropics, can be attributed to moderate land use and possibly, to the influence of nutrient-rich volcanic soils in the study area. Overall, plant species richness was lower in the secondary stands, but this difference was less pronounced in the smallest size classes (seedlings, saplings). Median percent similarity of all pairwise stand comparisons showed that floristic composition of saplings (stems 1 m tall and 5 cm DBH) was more similar between secondary and old-growth stands than for trees (stems 10 cm DBH). Because the potential value of secondary forests in conserving woody plant diversity appears highest for the young size classes, we suggest that further studies on floristic composition, especially those addressing the dynamics of the understory component, are needed to refine our understanding of the role of this natural resource in the maintenance of plant biodiversity in disturbed landscapes.     

The size and composition of the hymenopteran fauna of Costa Rica

An intensive survey of the hymenopteran fauna of Costa Rica provides an opportunity to explore the size and composition of a species-rich insect order in a large tropical region. A working estimate of the richness of the fauna is 20,000 species. This is consistent with some published estimates of the numbers of species of Hymenoptera worldwide, but at odds with suggestions that all insect species number several tens of millions. Sixty-one families of Hymenoptera have been collected in Costa Rica, and the numbers of species per unit area is more than twice that of most of the other regions for which data are available. The Costa Rican fauna has higher proportions of egg parasitoids and of eusocial species, and a lower proportion of primary phytophages than that of the British Isles.     

Moth assemblages in Costa Rica rain forest mirror small-scale topographic heterogeneity

In many tropical lowland rain forests, topographic variation increases environmental heterogeneity, thus contributing to the extraordinary biodiversity of tropical lowland forests. While a growing number of studies have addressed effects of topographic differences on tropical insect communities at regional scales (e.g., along extensive elevational gradients), surprisingly little is known about topographic effects at smaller spatial scales. The present study investigates moth assemblages in a topographically heterogeneous lowland rain forest landscape, at distances of less than a few hundred meters, in the Golfo Dulce region (SW Costa Rica). Three moth lineages—Erebidae–Arctiinae (tiger and lichen moths), the bombycoid complex, and Geometridae (inchworm moths)—were examined by means of automatic light traps in three different forest types: creek forest, slope forest, and ridge forest. Altogether, 6,543 individuals of 419 species were observed. Moth assemblages differed significantly between the three forest types regarding species richness, total abundance, and species composition. Moth richness and abundance increased more than fourfold and eightfold from creek over slope to ridge forest sites. All three taxonomic units showed identical biodiversity patterns, notwithstanding their strong differences in multiple eco-morphological traits. An indicator species analysis revealed that most species identified as characteristic were associated either with the ridge forest alone or with ridge plus slope forests, but very few with the creek forest. Despite their mobility, local moth assemblages are highly differentially filtered from the same regional species pool. Hence, variation in environmental factors significantly affects assemblages of tropical moth species at small spatial scales.     

Comparing forest structure and biodiversity on private and public land: secondary tropical dry forests in Costa Rica

Secondary forests constitute a substantial proportion of tropical forestlands. These forests occur on both public and private lands and different underlying environmental variables and management regimes may affect post‐abandonment successional processes and resultant forest structure and biodiversity. We examined whether differences in ownership led to differences in forest structure, tree diversity, and tree species composition across a gradient of soil fertility and forest age. We collected soil samples and surveyed all trees in 82 public and 66 private 0.1‐ha forest plots arrayed across forest age and soil gradients in Guanacaste, Costa Rica. We found that soil fertility appeared to drive the spatial structure of public vs. private ownership; public conservation lands appeared to be non‐randomly located on areas of lower soil fertility. On private lands, areas of crops/pasture appeared to be non‐randomly located on higher soil fertility areas while forests occupied areas of lower soil fertility. We found that forest structure and tree species diversity did not differ significantly between public and private ownership. However, public and private forests differed in tree species composition: 11 percent were more prevalent in public forest and 7 percent were more prevalent in private forest. Swietenia macrophylla, Cedrela odorata, and Astronium graveolens were more prevalent in public forests likely because public forests provide stronger protection for these highly prized timber species. Guazuma ulmifolia was the most abundant tree in private forests likely because this species is widely consumed and dispersed by cattle. Furthermore, some compositional differences appear to result from soil fertility differences due to non‐random placement of public and private land holdings with respect to soil fertility. Land ownership creates a distinctive species composition signature that is likely the result of differences in soil fertility and management between the ownership types. Both biophysical and social variables should be considered to advance understanding of tropical secondary forest structure and biodiversity.