Forests Of Costa Rica Research Articles

Cupania moralesii (Sapindaceae), a new endemic tree species from the premontane forest of Costa Rica

Cupania moralesii (Sapindaceae), a new endemic tree species from Costa Rica, is described and illustrated. The similarities and differences between this species and C. livida are discussed.

Tree species effects on pathogen-suppressive capacities of soil bacteria across two tropical dry forests in Costa Rica.

Antibiotic-producing bacteria in the genus Streptomyces can inhibit soil-borne plant pathogens, and have the potential to mediate the impacts of disease on plant communities. Little is known about how antibiotic production varies among soil communities in tropical forests, despite a long history of interest in the role of soil-borne pathogens in these ecosystems. Our objective was to determine how tree species and soils influence variation in antibiotic-mediated pathogen suppression among Streptomyces communities in two tropical dry forest sites (Santa Rosa and Palo Verde). We targeted tree species that co-occur in both sites and used a culture-based functional assay to quantify pathogen-suppressive capacities of Streptomyces communities beneath 50 focal trees. We also measured host-associated litter and soil element concentrations as potential mechanisms by which trees may influence soil microbes. Pathogen-suppressive capacities of Streptomyces communities varied within and among tree species, and inhibitory phenotypes were significantly related to soil and litter element concentrations. Average proportions of inhibitory Streptomyces in soils from the same tree species varied between 1.6 and 3.3-fold between sites. Densities and proportions of pathogen-suppressive bacteria were always higher in Santa Rosa than Palo Verde. Our results suggest that spatial heterogeneity in the potential for antibiotic-mediated disease suppression is shaped by tree species, site, and soil characteristics, which could have significant implications for understanding plant community composition and diversity in tropical dry forests.

Forests in Central America and Panama: which kind, how large and where?

Exploitation of natural forests works well as long as they are reasonably accessible, adequate in size and produce materials desired by the society served. However, as natural stands are exploited and lands are diverted to nonforest uses, it is likely that without an input of technical silviculture, the natural development of secondary and residual forests will be inadequate. This is particularly true of the diverse tropical hardwood forests where often relatively few species and even fewer stems per hectare produce desirable material. A serious technical problem presents itself in trying to match the complex forest production system with the utilization system. In early stages of exploitation of a natural tropical forest this match is likely to be poor as the forest conversion system is often simple with only one or two products and a small spectrum of industry, which usually is highly selective as to species, size and quality. Consequently a very small fraction of the trees and volume in a tropical hardwood stand has marketable utility. As long as there is surplus forest land, this situation can be tolerated. However, this utilization system of low concentration of marketable material per unit of area results in high operating costs in attempting to assemble meaningful quantities of material. This occurs even if the cost of the raw material itself is low. Furthermore, this system can result in depletion of useful material per unit area with time, as the unavoidable high grading that occurs commonly results in the replacement of usable forest stocking by unusable species, qualities, and sizes. As a result, the match between the forest production and utilization systems may worsen. Unfortunately the classical extensive forest inventories often conducted have not always proved a useful tool in assessing the utility of natural tropical forest stands. The usual approach allocates most of the resources to counting and measuring standing trees without regard to utility. In later analysis stages the data may be adjusted to reflect merchantability but merchantability in this sense is often based on arbitrary classifications of trees into use and size categories that often bear little relationship to the conversion system in use. Furthermore, conversion system standards change and the above merchantability impositions in inventories have generally failed to loo k at merchantable volumes in terms of flexible alternatives. As a result, the data from such inventories can be dangerously misleading in guiding planning discussions. This paper presents some preliminary results from a study aimed at providing a loo k at the match between the forest production and conversion systems when different sets of utilization standards are imposed on the forest. The results focus on three Costa Rican forest situations: the mixed natural forest at La Selva, dominated by Gavilan ( Pentaclethra macrolaba ) ; the mixed natural forest along the Atlantic coast dominated by Cativo ( Prioria copaifera ) and Cedro Macho ( Carapa guianensis ); and pure even-aged plantations. The mixed forests contain many trees of unusable species or qualities, such that over-all usable productivity is quite poor. This situation may be improved by either simplifying the forest structure by silviculture to favor the more usable species and/or increasing the complexity of the conversion system to enable a greater use efficiency of currently desired species and to include currently unused species.

A new blue-grey Veturius (Publius) Kaup of the northwestern Sierra de Talamanca, Costa Rica (Coleoptera: Passalidae)

Summary A new species of Veturius (Publius) Kaup, V. unanus n. sp., from a mountain cloud forest of Costa Rica, northwestern Sierra de Talamanca, Tapantí-Río Macho Massif, Province of Cartago, is described and illustrated. It is the first known Publius species with a blue-grey body color, matt elytra and shining or satiny elsewhere. The species is interpreted as sister species of V. (Publius) talamacaensis Boucher, 2006, from which it differs by a few characters. Both species are sympatric. V. unanus n. sp. is the northernmost endemic in the subgenus Publius.

A review of world Diallactiini (Diptera, Cecidomyiidae, Winnertziinae),with the description of six new genera and seventeen new species.

Fossil and extant Diallactiini, which are mycophagous Cecidomyiidae (gall midges), are reviewed globally for the first time. Johnsonomyia Felt, 1908 stat. rev. is restored from synonymy with Haplusia Karsch, 1877 (with Chastomera Skuse, 1888 confirmed as a junior synonym) and both genera are re-defined. Haplusia funebris Plakidas, 2007 and Wyattella lobata Yukawa, 1968 are newly combined in Johnsonomyia. Gynapteromyia Mamaev, 1965 is shown to be a species-rich, almost cosmopolitan genus, which absorbs several of the species previously classified in Haplusia or Chastomera. Gynapteromyia brevipalpis (Mamaev, 1964) comb. nov., G. heteroptera (Mamaev & Spungis, 1980) comb. nov., G. hondrui (Mamaev, 1964) comb. nov., G. indica (Grover, 1971) comb. nov., G. longipalpis (Mamaev, 1964) comb. nov., and G. stricta (Fedotova & Sidorenko, 2005) comb. nov. are all new combinations. †Palaeocolpodia eocenica Meunier, 1904 is considered to be a nomen dubium. Prior to the present study, the tribe Diallactiini contained 28 extant species classified in 6 genera. Previously unworked specimens of Diallactiini gathered by the author in the past 15 years were examined and identified as belonging to 57 different species, all unnamed. From that material, the following new taxa are described: Bruneiplusia gen. nov. (from Brunei), B. kaspraki sp. nov., Gynapteromyia costaricensis sp. nov. (Costa Rica), G. furcata sp. nov. (Costa Rica), G. novaezealandiae sp. nov. (New Zealand), G. tasmanica sp. nov. (Australia), G. temburong sp. nov. (Brunei), G. tenuistylata sp. nov. (Brunei), Haplusia afrotropica sp. nov. (South Africa), Japoplusia gen. nov. (Japan), Jap. honshuensis sp. nov., Johnsonomyia scabra sp. nov. (Costa Rica), John. serrata sp. nov. (South Africa), Loboplusia gen. nov. (Costa Rica), L. zurqui sp. nov., Makrostyles gen. nov. (Costa Rica), Makr. terrifica sp. nov., Mikrostyles gen. nov. (Brunei), Mikr. angustilobata sp. nov., Mikr. latolobata sp. nov., Wahabia gen. nov. (Brunei), Wah. mantici sp. nov., and Wyattella japonica sp. nov. (Japan). A key to the genera of Diallactiini based on male characters is presented. Diallactiini are shown to be a remarkably diverse group in terms of adult morphology. The genitalia of some male Diallactiini represent the most strongly modified such structures known in Winnertziinae. Morphological novelties found in Diallactiini, but no other Cecidomyiidae, include the fringed leg setae of Loboplusia and the furcate palpal sensilla in some Gynapteromyia and Mikrostyles. Diallactiini occur in all zoogeographic regions, with the highest generic and specific diversity found in the tropics (although Afrotropical diallactiines are poorly researched). Local diversity is also highest in the tropics, with as many as 29 species (unnamed or named in this paper) of at least 6 genera found at a single site, Zurquí de Moravia, in the cloud forest of Costa Rica. The best-explored fauna of Winnertziinae, including Diallactiini, is certainly that of Europe, but diallactiine biodiversity there is low and most of the nine European species are rarely encountered in the field. Gynapteromyia brevipalpis is reported from Sweden for the first time.

Forest composition modifies litter dynamics and decomposition in regenerating tropical dry forest.

We investigated how forest composition, litter quality, and rainfall interact to affect leaf litter decomposition across three successional tropical dry forests in Costa Rica. We monitored litter stocks and bulk litter turnover in 18 plots that exhibit substantial variation in soil characteristics, tree community structure, fungal communities (including forests dominated by ecto- or arbuscular mycorrhizal host trees), and forest age. Simultaneously, we decomposed three standard litter substrates over a 6-month period spanning an unusually intense drought. Decay rates of standard substrates depended on the interaction between litter identity and forest type. Decomposition rates were correlated with tree and soil fungal community composition as well as soil fertility, but these relationships differed among litter types. In low fertility soils dominated by ectomycorrhizal oak trees, bulk litter turnover rates were low, regardless of soil moisture. By contrast, in higher fertility soils that supported mostly arbuscular mycorrhizal trees, bulk litter decay rates were strongly dependent on seasonal water availability. Both measures of decomposition increased with forest age, as did the frequency of termite-mediated wood decay. Taken together, our results demonstrate that soils and forest age exert strong control over decomposition dynamics in these tropical dry forests, either directly through effects on microclimate and nutrients, or indirectly by affecting tree and microbial community composition and traits, such as litter quality.

Losing legs and walking hard: effects of autotomy and different substrates in the locomotion of harvestmen in the genusPrionostemma

Autotomy, the strategy of voluntarily releasing a leg during an encounter with a potential predator or in agonistic interactions between conspecifics, is common in animals. The potential costs of this behavior have been scarcely studied. In addition, locomotion and substrate-dependent performance might be affected by autotomy. We did a comparative and observational study to investigate whether losing legs affects the escape speed and trajectory of harvestmen in the genus Prionostemma Pocock, 1903 (Eupnoi: Sclerosomatidae) on different substrates: soil (the least roughened), smooth bark and mossy bark (the most roughened) in a tropical premontane forest in Costa Rica. We observed that 71% of the individuals found were missing at least one leg. Harvestmen, regardless of leg condition, walked faster and made fewer turns in their trajectory in the soil. While climbing, they were faster on smooth bark than in moss. On all substrates, autotomized individuals were slower and had a more erratic trajectory than intact ones. The type of missing legs (sensory or locomotor) had no influence on the speed or trajectory. We experimentally induced autotomy and found that walking speed on soil decreases if individuals lose a leg. Our findings confirm that losing legs affects locomotion, and we provide novel insights on how locomotion in these harvestmen depends on surface roughness. Our data suggest that moss could be a type of substrate that requires more elaborate skills in balance, orientation and texture recognition than smooth bark.

Neighborhood structure influences the convergence in light capture efficiency and carbon gain: an architectural approach for cloud forest shrubs.

Although plant competition is recognized as a fundamental factor that limits survival and species coexistence, its relative importance on light capture efficiency and carbon gain is not well understood. Here, we propose a new framework to explain the effects of neighborhood structures and light availability on plant attributes and their effect on plant performance in two understory shade-tolerant species (Palicourea padifolia (Roem. & Schult.) C.M. Taylor & Lorence and Psychotria elata (Swartz)) within two successional stages of a cloud forest in Costa Rica. Features of plant neighborhood physical structure and light availability, estimated by hemispherical photographs, were used to characterize the plant competition. Plant architecture, leaf attributes and gas exchange parameters extracted from the light-response curve were used as functional plant attributes, while an index of light capture efficiency (silhouette to total area ratio, averaged over all viewing angles, STAR) and carbon gain were used as indicators of plant performance. This framework is based in a partial least square Path model, which suggests that changes in plant performance in both species were affected in two ways: (i) increasing size and decreasing distance of neighbors cause changes in plant architecture (higher crown density and greater leaf dispersion), which contribute to lower STAR and subsequently lower carbon gain; and (ii) reductions in light availability caused by the neighbors also decrease plant carbon gain. The effect of neighbors on STAR and carbon gain were similar for the two forests sites, which were at different stages of succession, suggesting that the architectural changes of the two understory species reflect functional convergence in response to plant competition. Because STAR and carbon gain are variables that depend on multiple plant attributes and environmental characteristics, we suggest that changes in these features can be used as a whole-plant response approach to detect environmental filtering in highly diverse tropical forest communities.

Recovery following clearing of an upper montane Quercus forest in Costa Rica

Pattems in recovery following clearing of upper montane Quercus forests (2900 - 3000 m alt.) in the Costa Rican Cordillera de Talamanca have been studied and four different successional forest phases (pioneer, ear1y successional, rnid-successional, mature) have been distinguished. Arboreal species richness increases during succession being largest in lhe mid-successional forest phase. Woody Asteraceae dominate lhe ear1y secondary phases, while Araliaceae, Lauraceae and to a lesser extent Myrsinaceae become prominent in later phases including lhe mature stage. Quercus recovers largely, being the dominant genus in mid-successional and mature foresto Young secondary phases are rich in rapid-growing light-demanding canopy species, while more developed multi-layered phases are dominated by a large number of shade-tolerant subcanopy species. In general, secondary succession may lead (within a period of approximately 35 years after clearing and abandonment) to an amoreal recovery ofabout 70 % of the original tree species composition in mature forest.

Assessing the Effectiveness of Reforestation Efforts in the Tropical Montane Cloud Forest of Costa Rica

Tropical montane cloud forests are important and unique ecosystems in Costa Rica. However, a large percentage of them have been cleared since the 1950s to make way for agriculture. Cloudbridge Nature Reserve, a privately-owned reforestation project and research station in south-central Costa Rica, is working to return its abandoned pastures back to their natural climax cloud forest state through various reforestation efforts. Because of the costly nature of reforestation, Cloudbridge would greatly benefit from knowing how effective its work has been thus far. To answer this question, tree surveys were conducted at three sites within the Reserve, encompassing a mix of forest cover types: manually planted forest cover and natural regeneration of various ages. Specimens were classified as pioneer or climax species, and the quantities of individuals of each species class found in each type of forest cover were compared. Furthermore, forest stand parameters such as ratio of tree biomass to total biomass, above-ground biomass, and average stand diameter were used to determine and compare successional forest stages of the sites surveyed. Fisher’s exact tests and one-way ANOVA were employed to conclude that the reforestation efforts at Cloudbridge are definitely aiding the cloud forest to regenerate more quickly than it would naturally, but it is unclear exactly how much they help.

Higher survival drives the success of nitrogen-fixing trees through succession in Costa Rican rainforests.

Trees capable of symbiotic nitrogen (N) fixation ('N fixers') are abundant in many tropical forests. In temperate forests, it is well known that N fixers specialize in early-successional niches, but in tropical forests, successional trends of N-fixing species are poorly understood. We used a long-term census study (1997-2013) of regenerating lowland wet tropical forests in Costa Rica to document successional patterns of N fixers vs non-fixers, and used an individual-based model to determine the demographic drivers of these trends. N fixers increased in relative basal area during succession. In the youngest forests, N fixers grew 2.5 times faster, recruited at a similar rate and were 15 times less likely to die as non-fixers. As succession proceeded, the growth and survival disparities decreased, whereas N fixer recruitment decreased relative to non-fixers. According to our individual-based model, high survival was the dominant driver of the increase in basal area of N fixers. Our data suggest that N fixers are successful throughout secondary succession in tropical rainforests of north-east Costa Rica, and that attempts to understand this success should focus on tree survival.

Re‐growing a tropical dry forest: functional plant trait composition and community assembly during succession

SummaryA longstanding goal of ecology and conservation biology is to understand the environmental and biological controls of forest succession. However, the patterns and mechanisms that guide successional trajectories, especially within tropical forests, remain unclear.We collected leaf functional trait and abiotic data across a 110‐year chronosequence within a tropical dry forest in Costa Rica. Focusing on six key leaf functional traits related to resource acquisition and competition, along with measures of forest stand structure, we propose a mechanistic framework to link species composition, community trait distributions and forest structure. We quantified the community‐weighted trait distributions for specific leaf area, leaf dry matter concentration, leaf phosphorus concentration, leaf carbon to nitrogen ratio and leaf stable isotopic carbon and nitrogen. We assessed several prominent hypotheses for how these functional measures shift in response to changing environmental variables (soil water content, bulk density andpH) across the chronosequence.Increasingly, older forests differed significantly from younger forests in species composition, above‐ground biomass and shifted trait distributions. Early stages of succession were uniformly characterized by lower values of community‐weighted mean specific leaf area, leaf stable nitrogen isotope and leaf phosphorus concentration. Leaf dry matter concentration and leaf carbon to nitrogen ratio were lower during earlier stages of succession, and each trait reached an optimum during intermediate stages of succession. The leaf carbon isotope ratio was the only trait to decrease linearly with increasing stand age indicating reduced water use efficiency in older forests. However, in contrast with expectations, community‐weighted trait variances did not generally change through succession, and when compared to null expectations were lower than expected.The observed directional shift in community‐weighted mean trait values is consistent with the ‘productivity filtering’ hypothesis where a directional shift in water and light availability shifts physiological strategies from ‘slow’ to ‘fast’. In contrast with expectations arising from niche based ecology, none of the community trait distributions were over‐dispersed. Instead, patterns of trait dispersion are consistent with the abiotic filtering and/or competitive hierarchy hypotheses.

Spatial patterns of primary seed dispersal and adult tree distributions:Genipa americanadispersed byCebus capucinus

Abstract:The spatial distribution of adult trees is typically not expected to reflect the spatial patterns of primary seed dispersal, due to many factors influencing post-dispersal modification of the seed shadow, such as seed predation, secondary seed dispersal and density-dependent survival. Here, we test the hypothesis that spatial distributions of primary seed shadows and adult trees are concordant by analysing the spatial distributions of adultGenipa americanatrees and the seed shadow produced by its key primary disperser, the capuchin monkey (Cebus capucinus) in a tropical dry forest in Costa Rica. We mapped the dispersal ofG. americanaseeds by the capuchins during focal animal follows (mean = 463 min,n= 50) of all adults in one free-ranging group over two early wet seasons (May–July, 2005 and 2006). We mapped the locations of allG. americanatrees within a 60-ha plot that lay within the home range of the capuchin group. We conducted multiple spatial point pattern analyses comparing degrees of clustering of capuchin defecations andG. americanatrees. We found that adult tree distributions and primary dispersal patterns are similarly aggregated at multiple spatial scales, despite the modification of the primary dispersal patterns and long dispersal distances.

Generic Composition, Structure and Diversity of Secondary Forests at Amisconde, the Pacific Slope of the Cordillera de Talamanca, Costa Rica

Most Costa Rican forests have been intensively studied in recent years. One exception is the transition zone from lowland wet forest to the high elevatíon Quercus forest belt al Ihe pacific slopes of the Cordillera de Talamanca. An inventory of secondary forest composition, structure and diversity was done on a specific slope (l150- 2300-m elevation) in the conservation and development project Amisconde. Thirteen plots of 500 m2 were evenly spread a10ng an elevation gradient. Specimens were collected of a11 woody individuals (> 3 cm DBH), dried, placed in a herbarium of morphospecies and afterwards identified. In total 90 genera within 49 families were found. The vegetation was separated in three forest types using TWINSPAN c1assification. Forest types were elevatíon based. Elevation and forest age showed (overall) no correlatíon with diversity using ANOVA, with the single exceptíon of a positíve correlatíon of the number of genera and elevatíon. This was opposite to the negative correlations mostly found on elevatíon gradients. The main factors for this positíve correlation were the level of recent disturbance and the distance to primary forest, in combination wíth forest age

Scatter hoarding of seeds confers survival advantages and disadvantages to large-seeded tropical plants at different life stages.

Scatter hoarding of seeds by animals contributes significantly to forest-level processes, including plant recruitment and forest community composition. However, the potential positive and negative effects of caching on seed survival, germination success, and seedling survival have rarely been assessed through experimental studies. Here, I tested the hypothesis that seed burial mimicking caches made by scatter hoarding Central American agoutis (Dasyprocta punctate) enhances seed survival, germination, and growth by protecting seeds from seed predators and providing favorable microhabitats for germination. In a series of experiments, I used simulated agouti seed caches to assess how hoarding affects seed predation by ground-dwelling invertebrates and vertebrates for four plant species. I tracked germination and seedling growth of intact and beetle-infested seeds and, using exclosures, monitored the effects of mammals on seedling survival through time. All experiments were conducted over three years in a lowland wet forest in Costa Rica. The majority of hoarded palm seeds escaped predation by both invertebrates and vertebrates while exposed seeds suffered high levels of infestation and removal. Hoarding had no effect on infestation rates of D. panamensis, but burial negatively affected germination success by preventing endocarp dehiscence. Non-infested palm seeds had higher germination success and produced larger seedlings than infested seeds. Seedlings of A. alatum and I. deltoidea suffered high mortality by seed-eating mammals. Hoarding protected most seeds from predators and enhanced germination success (except for D. panamensis) and seedling growth, although mammals killed many seedlings of two plant species; all seedling deaths were due to seed removal from the plant base. Using experimental caches, this study shows that scatter hoarding is beneficial to most seeds and may positively affect plant propagation in tropical forests, although tradeoffs in seed survival do exist.

Do foliar, litter, and root nitrogen and phosphorus concentrations reflect nutrient limitation in a lowland tropical wet forest?

Understanding nutrient limitation of net primary productivity (NPP) is critical to predict how plant communities will respond to environmental change. Foliar nutrients, especially nitrogen and phosphorus concentrations ([N] and [P]) and their ratio, have been used widely as indicators of plant nutritional status and have been linked directly to nutrient limitation of NPP. In tropical systems, however, a high number of confounding factors can limit the ability to predict nutrient limitation —as defined mechanistically by NPP responses to fertilization— based on the stoichiometric signal of the plant community. We used a long-term full factorial N and P fertilization experiment in a lowland tropical wet forest in Costa Rica to explore how tissue (foliar, litter and root) [N] and [P] changed with fertilization, how different tree size classes and taxa influenced the community response, and how tissue nutrients related to NPP. Consistent with NPP responses to fertilization, there were no changes in community-wide foliar [N] and [P], two years after fertilization. Nevertheless, litterfall [N] increased with N additions and root [P] increased with P additions. The most common tree species (Pentaclethra macroloba) had 9 % higher mean foliar [N] with NP additions and the most common palm species (Socratea exohrriza) had 15% and 19% higher mean foliar [P] with P and NP additions, respectively. Moreover, N:P ratios were not indicative of NPP responses to fertilization, either at the community or at the taxa level. Our study suggests that in these diverse tropical forests, tissue [N] and [P] are driven by the interaction of multiple factors and are not always indicative of the nutritional status of the plant community.

<strong>Two new species of Scheloribatidae (Acari, Oribatida) from Costa Rica</strong>

Two new species of oribatid mites of the family Scheloribatidae, Scheloribates costaricensis sp. nov. and Perscheloribates paraluminosus sp. nov., are described from leaf litter of secondary forest in Costa Rica. Scheloribates costaricensis sp. nov. is most similar morphologically to Scheloribates brasilosphericus Badejo, Woas & Beck, 2002, however, it differs from the latter by morphology of bothridial and adoral setae, length of prodorsal setae, body surface, structure of antero-ventral part of leg femora, and the presence of large tubercle on posterior margin of notogaster and well visible dorsal notogastral setae. Perscheloribates paraluminosus sp. nov. is most similar morphologically to Perscheloribates luminosus (Hammer, 1961), however, it differs from the latter by body length and color, structure of rostrum, length of rudimentary parts of translamellar line, and the presence of two longitudinal furrows in anogenital region.

<p class="Body"><strong>Two new species of oribatid mites (Acari, Oribatida) with auriculate pteromorphs from Costa Rica, including a key to all species of <em>Galumna</em> (<em>Galumna</em>) of the Neotropical region</strong></p>

Two species of oribatid mites with auriculate pteromorphs, Truncozetes paraecuadoriensis sp. nov. and Galumna paraoctopunctata sp. nov. , are described from leaf litter of secondary forest in Costa Rica. Truncozetes paraecuadoriensis sp. nov. is most similar to T. ecuadoriensis Ermilov, Sandmann, Marian & Maraun, 2013, however, it differs from the latter by the body size, morphology of interlamellar and bothridial setae, structure of translamella and surface of epimeral region. Galumna paraoctopunctata sp. nov. is most similar to G. octopunctata (Ewing, 1909), however, it differs from the latter by the body size, structure of lamellar lines and morphology of notogastral porose areas A3 . The genus Truncozetes is recorded for the first time in Costa Rica.

Climate oscillations and conservation measures regulate white-faced capuchin population growth and demography in a regenerating tropical dry forest in Costa Rica

Tropical dry forests are among the world’s most imperiled biomes, and most long-lived and large-bodied animals that inhabit tropical dry forests persist in small, fragmented populations. Long-term monitoring is necessary for understanding the extent to which such populations can cope with changing climate conditions and recover after the elimination of human disturbances. We investigated how conservation measures, local rainfall patterns, and large-scale climate oscillations have affected the population dynamics of white-faced capuchins (Cebus capucinus) in a Costa Rican tropical dry forest over a 42-year period after the elimination of most human disturbances. The population’s rapid initial growth and later stabilization suggests that it was below the habitat’s carrying capacity at the time of the conservation area’s establishment. Management practices, such as aggressive fire suppression, may have played an important role in promoting this growth. Rainfall patterns were strongly coupled with phases and intensity conditions of the El Niño Southern Oscillation. The population experienced two distinct growth phases after the conservation area’s establishment, a period of rapid growth through the 1980s and 1990s and a subsequent period of stability from about 2000 to the present. El Niño-like conditions in the three years preceding a census year were associated with declines in reproductive output and/or offspring mortality during the rapid growth phase. The sensitivity of this ecosystem to global climatic phenomena suggests that some animals will be negatively affected if drought years become more common as the global climate warms.

Changes in the apparent survival of a tropical bird in response to the El Niño Southern Oscillation in mature and young forest in Costa Rica.

The effects of habitat alteration and climatic instability have resulted in the loss of bird populations throughout the globe. Tropical birds in particular may be sensitive to climate and habitat change because of their niche specialization, often sedentary nature, and unique life-cycle phenologies. Despite the potential influence of habitat and climatic interactions on tropical birds, we lack comparisons of avian demographics from variably aged forests subject to different climatic phenomena. Here, we measured relationships between forest type and climatic perturbations on White-collared Manakin (Manacus candei), a frugivorous tropical bird, by using 12 years of capture data in young and mature forests in northeastern Costa Rica. We used Cormack-Jolly-Seber models and an analysis of deviance to contrast the influence of the El Niño Southern Oscillation (ENSO) on manakin survival. We found that ENSO had little effect on manakin survival in mature forests. Conversely, in young forests, ENSO explained 79% of the variation where dry El Niño events negatively influenced manikin survival. We believe mature forest mitigated negative effects of dry El Niño periods and can serve as refugia for some species by buffering birds from climatic instability. Our results represent the first published documentation that ENSO influences the survival of a resident Neotropic landbird.