Atlantic Zone Of Costa Rica Research Articles

Diet and reproduction of the fish Joturus pichardi (Mugiliformes: Mugilidae) in the Pacuare River basin, Costa Rica

Introduction: Joturus pichardi is an important migratory species that inhabits the rivers of the Atlantic zone of Costa Rica and has been little studied. Objective: To describe the diet and reproduction of J. pichardi and its relationship with environmental factors in the Pacuare River basin. Methods: Sixteen sampling sites were selected along the main channel or Pacuare River. The samplings were performed from October 2015 to October 2016. The gonads, stomach, and intestines of seven individuals of J. pichardi were analyzed. The relationship of J. pichardi between the physicochemical variables of the water and the structure of the habitat was analyzed. Results: Twenty individuals were collected at an elevation of 225-235masl. The occurrence of J. pichardi was related to sites with higher river velocity, high values of dissolved oxygen, rock substrate and forest land use. All the individuals analyzed had visceral fat and endoparasites in the stomach. Bryophytes, ferns, macroinvertebrates, and detritus were identified as part of the diet of J. pichardi. According to the analysis of gonads in adults, the individuals were identified in the gonadal state types I, II and V. Conclusions: Our results suggest J. pichardi is an omnivorous species associated with sites with rocks, rapids, well-oxygenated waters, and forest land use. Also, the analysis of gonads coincides with the known reproduction period of the species. Finally, individuals of Neoechinorhynchus spp. are recorded for the first time in stomachs of J. pichardi in Costa Rica.

Effects of Weed Cover Composition on Insect Pest and Natural Enemy Abundance in a Field ofDracaena marginata(Asparagales: Asparagaceae) in Costa Rica

Weeds and their influence on pest and natural enemy populations were studied on a commercial ornamental farm during 2009 in the Atlantic Zone of Costa Rica. A baseline survey of the entire production plot was conducted in February, along a 5 by 5 m grid to characterize and map initial weed communities of plants, cicadellids, katydids, and armored scales. In total, 50 plant species from 21 families were found. Seven weed treatments were established to determine how weed manipulations would affect communities of our targeted pests and natural enemies. These treatments were selected based on reported effects of specific weed cover on herbivorous insects and natural enemies, or by their use by growers as a cover crop. Treatments ranged from weed-free to being completely covered with endemic species of weeds. Although some weed treatments changed pest abundances, responses differed among arthropod pests, with the strongest effects observed for Caldwelliola and Empoasca leafhoppers. Removal of all weeds increased the abundance of Empoasca, whereas leaving mostly cyperacaeous weeds increased the abundance of Caldwelliola. Weed manipulations had no effect on the abundance of katydid and scale populations. No weed treatment reduced the abundance of all three of the target pests. Differential responses of the two leafhopper species to the same weed treatments support hypotheses, suggesting that noncrop plants can alter the abundance of pests through their effects on arthropod host finding and acceptance, as well as their impacts on natural enemies.

Land speculation and interest rate subsidies as a cause of deforestation: The role of cattle ranching in Costa Rica

Land speculation by cattle ranchers is considered a principal cause of deforestation in Latin America, in particular in combination with (previously) widely provided interest rate subsidies. Proof for the hypothesis that land speculation leads to inflated rates of investment in land is, however, relatively limited and invariably related to the question of whether land prices tend to rise over time. Based on the Neoclassical investment theory with adjustment costs we develop a stochastic cattle ranching model in which land prices are modelled as geometric Brownian motion, to evaluate the effect of expected fluctuations in land prices on land investment decisions by cattle ranchers in Latin America. For a case study in the Atlantic Zone of Costa Rica, results show that the expected rate of investment is almost 35% underestimated in case land prices are assumed constant instead of fluctuating according to the standard deviation, while abolition of interest rate subsidies leads to an almost 15% decrease in the expected rate of investment. Consequently, it is shown that variability in land prices alone is a sufficient condition for land speculation, inflated rates of investment in land, larger farm sizes and, thus, higher rates of deforestation in agrarian frontier areas, while this process is further promoted by subsidized livestock credit or any other form of agricultural subsidy that increases the marginal production value of land.

Critiquing governmentality

This article sets out to test the Foucauldian concept of governmentality as it has been applied by social theorists working on the topic of neoliberal managerialism. It starts with a critical discussion of the 'good governance' agenda as developed by the World Bank. The question that the article poses is whether such technologies of governance are as successful in shaping new fields of intervention as assumed in the (managerial) governmentality literature. This question is answered negatively by way of a case study of an extensionist, working in an integrated rural development project in the Atlantic zone of Costa Rica, who developed his own 'participatory extension style of operation' for dealing with farmer beneficiaries. At a more theoretical level, the article takes issue with current notions regarding the malleability of the Self and the 'social'. The article concludes that the governmentality approach has perverse consequences for the anthropological project as it leads to an impoverished kind of ethnography.

An interdisciplinary approach to regional land use analysis using GIS, with applications to the Atlantic Zone of Costa Rica

AbstractPolicy makers and other stakeholders concerned with regional rural development increasingly face the need for instruments that can improve transparency in the policy debate and that enhance understanding of opportunities for and limitations to development. To this end, a methodology called SOLUS (Sustainable Options for Land Use) was developed by an interdisciplinary team of scientists over a 10‐year period in the Atlantic Zone of Costa Rica. The main tools of SOLUS include a linear programming (LP) model, two expert systems that define technical coefficients for a large number of production activities, and a geographic information system (GIS). A five‐step procedure was developed for GIS to spatially reference biophysical and economic parameters, to create input for the expert systems and the LP model, to store and spatially reference model output data, and to create maps of both model input and output data. SOLUS can be used to evaluate the potential effects of alternative policies and incentive structures on the performance of the agricultural sector. A number of practical applications demonstrate SOLUS's capability to quantify trade‐offs between economic objectives (income, employment) and environmental sustainability (soil nutrient balances, pesticide use, greenhouse gas emissions). GIS‐created maps visualize the spatial aspects of such trade‐offs and indicate hotspots where local goals may conflict with regional goals.

An interdisciplinary approach to regional land use analysis using GIS, with applications to the Atlantic Zone of Costa Rica

An interdisciplinary approach to regional land use analysis using GIS, with applications to the Atlantic Zone of Costa Rica

Spatial and temporal variation in soil CO 2 efflux in an old-growth neotropical rain forest, LA Selva, Costa Rica

Our objectives were to quantify and compare soil CO2 efflux of two dominant soil types in an old-growth neotropical rain forest in the Atlantic zone of Costa Rica, and to evaluate the control of environmental factors on CO2 release. We measured soil CO2 efflux from eight permanent soil chambers on six Oxisol sites. Three sites were developed on old river terraces (‘old alluvium’) and the other three were developed on old lava flows (‘residual’). At the same time we measured soil CO2 concentrations, soil water content and soil temperature at various depths in 6 soil shafts (3 m deep). Between ‘old alluvium’ sites, the two-year average CO2 flux rates ranged from 117.3 to 128.9 mg C m−2 h−1. Significantly higher soil CO2 flux occurred on the ‘residual’ sites (141.1 to 184.2 mg C m−2 h−1). Spatial differences in CO2 efflux were related to fine root biomass, soil carbon and phosphorus concentration but also to soil water content. Spatial variability in CO2 storage was high and the amount of CO2 stored in the upper and lower soil profile was different between ‘old alluvial’ and ‘residual’ sites. The major factor identified for explaining temporal variations in soil CO2 efflux was soil water content. During periods of high soil water content CO2 emission decreased, probably due to lower diffusion and CO2 production rates. During the 2-year study period inter-annual variation in soil CO2 efflux was not detected.

Labour, leisure and household income in rural settlements: an empirical assessment in the Atlantic Zone of Costa Rica

The relationship between labour use, the availability of leisure time and the generation of income in rural farm households is often depicted as an implicit or explicit trade-off. This article presents a review of current theories regarding the supply, demand and use of labour at farm household level, followed by an empirical assessment of time allocation of labour and the composition of farm household income in a sample of peasant households located in different types of agrarian settlements at the Atlantic Zone of Costa Rica. Structural determinants of labour use and leisure choice, as well as the relationship between household income and the availability of leisure are determined. Major differences in land use and labour allocation between settlements according to the period of colonization (old or recent) and the type of colonization (spontaneous or organized) are outlined. Small farms in organized settlements rely on labour-intensive cropping systems that guarantee higher incomes at the expense of leisure, while farms in spontaneous and more remote settlements still maintain labour-extensive production with reliance on wage labour. Empirical evidence points towards a clear trade-off between leisure-time and marginal income as well as possibilities for substitution of family labour by hired labour to increase leisure. Personal characteristics ( i.e. education, age, work attitudes) and farm characteristics ( i.e. location, farm size, lifetime) are identified as relevant factors to explain leisure choice.

Establishment of two indigenous timber species in dairy pastures in Costa Rica

A silvopastoral model that combines the production of pasture herbage with valuable native timber species has potential to simultaneously address the multiple goals of reforestation, conservation of native species and enterprise intensification. The objective of this study was to design, establish and monitor early growth of a silvopastoral experiment on a dairy farm in the north Atlantic zone of Costa Rica. Two indigenous timber species, Vochysia guatemalensis and Hyeronima alchorneoides were planted with and without the tropical pasture legume, Arachis pintoi in a split plot design, (2 × 2) factorial arrangement of treatments with four replications. After the first two years, V. guatemalensis was significantly taller (3.1 m) than H. alchorneoides (2.5 m). The mean root collar diameter for V. guatemalensis was significantly larger (6.5 cm) than H. alchorneoides (4.5 cm). Two-year establishment was acceptable for the tree component (83 to 85% survival) but poor for A. pintoi (2 to 8% of the sward). The most important pest affecting the establishment of the timber species was the leaf cutter ant, Atta cephalotes. An insect larvae, Cosmopterix sp., severely damaged 39% of the V. guatemalensis trees by repeatedly attacking their apical meristems. The two-year establishment data was insufficient to accurately predict future wood volume. A hypothetical economic analysis concluded that the silvopastoral system must average at least 1.2 m3 wood volume/paddock/year (20 m3/ha/year) throughout the first ten years of growth to assure a positive economic return from timber. The experiment is planned for a ten year period, which corresponds to the estimated rotation length for harvesting the timber species.

A goal-oriented approach to identify and engineer land use systems

This paper describes a formalized approach to identify and engineer future-oriented land use systems. Such land use systems can be used to explore options for strategic decision making with respect to land use policy and to do ex-ante assessment of land use alternatives to be further tested or developed in experimental settings. The so-called goal-oriented approach consists of three steps: (1) goal-oriented identification and design of land use systems; (2) quantification of biophysical production possibilities; and (3) defining the optimal mix of inputs, i.e. the production technique, required to realize production possibilities. The goal-oriented identification and design depends on the land-related objectives of a system under study, whereas plant, animal and environmental characteristics determine biophysical production possibilities. Characteristics of the production technique determine the realization of production possibilities. General guidelines are given to structure the specification and number of alternatives to be explored and to apply agro-ecological principles required for quantification of future-oriented land use systems. Concepts of the approach are illustrated with data from the northern Atlantic zone of Costa Rica and the Sudano–Sahelian zone of Mali. Finally, suggestions are given for the application of the approach at spatial and temporal scales exceeding the field level and time horizon of 1 year.

Uncertainty in technical coefficients for future-oriented land use studies: a case study for N-relationships in cropping systems

Engineering of land use systems for policy-oriented future studies and the development of new farming systems requires various information sources. Often, both process knowledge and data are subject to uncertainty that affects quantification of land use systems in their inputs and outputs. This paper analyzes the effects of uncertainty in three important N-relationships relevant for quantification of future-oriented cropping systems: (i) N-leaching as function of crop characteristics, (ii) N-concentration as function of yield level, and (iii) the recovery of crop residue-N. Based on verifiable assumptions, uncertainty in these three N-relationships is specified in terms of N-loss and production costs of cropping systems. Data and process knowledge as applied in LUCTOR, a summary model to design and quantify inputs and outputs of cropping systems for the northern Atlantic zone of Costa Rica, are used as a case study. All three relationships and their uncertainty have a major impact on N-loss of cropping systems, while effects on costs are limited and depend on the share of costs for fertilizer management in total production costs. Analyses as presented explicitly specify uncertainty of process knowledge and data used in future-oriented studies. Therefore, such analyses enable a better management or reduction of uncertainty through the identification of cropping systems with smaller uncertainty margins, and identification of research aimed at a more complete understanding of involved processes.

Soil microbial biomass and activity in tropical riparian forests

A large body of work has demonstrated that riparian ecosystems play a critical role regulating interactions between terrestrial and aquatic components of temperate zone landscapes. However, there have been relatively few studies of the role of riparian forests in tropical landscapes. There is a strong need to evaluate the effects of conversion of these forests to pasture and residential land uses on their ability to prevent the movement of nutrients and other pollutants to coastal water bodies. The objectives of this study were (1) to measure a suite of microbial properties that are indicators of the ability of soils to attenuate pollutants and cycle nitrogen (N) in tropical riparian forests under different land use management and (2) to evaluate the effects of conversion of two types of tropical forested wetlands (cativo, Prioria copaifera and yolillo, Raphia taedigera) on this same suite of soil microbial variables. To accomplish objective #1, we measured these variables in surface soils in intact forest, disturbed forest, pasture and residential land use sites in two locations in the Atlantic Zone of Costa Rica. For objective #2 we measured these variables in surface soils of three replicate intact and converted cativo and yolillo forests. Results suggest that land use conversion does not decrease levels of microbial biomass and activity in these soils. Intact forest sites did not have higher levels of microbial biomass and activity than ‘disturbed sites.’ In several cases, levels of these variables were consistently lower in intact forest than disturbed sites. There were no statistically significant differences between intact and converted cativo and yolillo sites. The relatively low level of activity in the intact sites is likely a ‘succession effect’, where the disturbed sites have younger, more actively growing vegetation that supplies more readily available organic matter to the soil microbial community. High correlations between soil organic matter and microbial biomass and activity strongly support this ‘successional’ explanation of our results.

The Need for Scale Sensitive Approaches in Spatially Explicit Land Use Change Modeling

This paper introduces some of the issues that are relevant to the spatially explicit modeling of land use systems. A short overview is given of the ways and means in which a number of different land use change models describe the land use system. Specific attention is given to the empirical modeling approach used in the CLUE (Conversion of Land Use and its Effects) modeling framework. This approach is demonstrated for three case studies in China, Ecuador and the Atlantic Zone of Costa Rica. These case-studies illustrate the methodology for multi-scale analysis of land use driving factors and their application in spatially explicit modeling exercises. Model functioning, performance and limitations are discussed. The presented case-studies indicate that empirical modeling results can contribute to a better theoretic imbedding of land use change research in scale sensitive and integrated theories.

Simulation of nitrous oxide and nitric oxide emissions from tropical primary forests in the Costa Rican Atlantic Zone

Nitrous oxide (N 2O) and nitric oxide (NO) are important atmospheric trace gases participating in the regulation of global climate and environment. Predictive models on the emissions of N 2O and NO emissions from soil into the atmosphere are required. We modified the CENTURY model (Soil Sci. Soc. Am. J., 51 (1987) 1173) to simulate the emissions of N 2O and NO from tropical primary forests in the Atlantic Zone of Costa Rica at a monthly time step. Combined fluxes of N 2O and NO were simulated as a function of gross N mineralization and water-filled pore space (WFPS). The coefficients for partitioning N 2O from NO were derived from field measurements (Global Biogeochem. Cycles, 8 (1994) 399). The modified CENTURY was calibrated against observations of carbon stocks in various pools of forest ecosystems of the region, and measured WFPS and emission rates of N 2O and NO from soil to the atmosphere. WFPS is an important factor regulating nutrient cycling and emissions of N2O and NO from soils making the accuracy of the WFPS prediction central to the modeling process. To do this, we modified the hydrologic submodel and developed a new method for the prediction of WFPS at the monthly scale from daily rainfall information. The new method is based on: (1) the relationship between monthly rainfall and the number of rainfall events, and (2) the relative cumulative frequency distribution of ranked daily rainfall events. The method is generic and should be applicable to other areas. Simulated monthly average WFPS was 0.68±0.02 — identical with the field measurement average of 0.68±0.02 from the annual cycle observed by Keller and Reiners (Global Biogeochem. Cycles, 8 (1994) 399). Simulated fluxes of N 2O and NO were 52.0±9.4 mg-N m −2 month −1 and 6.5±0.7 mg-N m −2 month −1, respectively, compared with measured averages of 48.2±11.0 mg-N m −2 month −1 and 7.1±1.1 mg-N m −2 month −1. The simulated N 2O/NO ratio was 11.2±1.9 compared with the measured value of 10.9±4.7. WFPS is the dominant determinant of the fraction of gross N mineralization that is emitted from the soil as N 2O and NO. If WFPS were not limiting during part of the year, this fraction would be 4.2%. With some periods of lower WFPS, the realized fraction is 2.2%. Because of the strong relationships between N 2O and NO emission rates and rainfall and its derivative, WFPS, these moisture variables can be used to scale up nitrogen trace gas fluxes from sites to larger spatial scales.

Regional analysis of soil-atmosphere nitrous oxide emissions in the Northern Atlantic Zone of Costa Rica

Summary Regional analysis of greenhouse gas emissions is becoming increasingly important in answering questions related to environmental change, and typically employs a Geographic Information System (GIS) linked with a process-based simulation model. For the Northern Atlantic Zone (NAZ) in Costa Rica (281 649 ha), a regional analysis of soil–atmosphere nitrous oxide fluxes from the dominant land-use types forest, cattle pastures, and banana plantations was performed with both deterministic and stochastic variable representations. The stochastic representation accounted for soil and land management variability across nongeoreferenced fields within 1572 georeferenced land units in 13 relevant classes. Per class, frequency distributions of field-scale fluxes were simulated with a process-based model and Monte Carlo methods. Stochastic incorporation of both soil and land use variability resulted in areal (i.e. land unit-scale) fluxes that were 14–22% lower than estimates based on averaged inputs. Soil heterogeneity was dominant. In addition, spatial flux patterns for current (1992) land use and two alternative land-use scenarios were evaluated using stochastic inputs. With current management, the regional nitrous oxide-N flux (standard deviation in parentheses) from agricultural land was 0.43 (0.13) Gg y−1. Replacing natural grasses with mixtures of grasses and N-fixing species on relevant soil types and introducing different forms of banana plantation management (alternative I) increased the regional flux by 51% to 0.65 (0.22) Gg y−1. When all natural grasses were replaced by fertilized improved species and allowing different forms of banana plantation management (alternative II), the regional flux increased by 126% to 0.97 (0.68) Gg y−1. Using the revised IPCC methodology, the 1992 nitrous oxide emission from agriculture in the NAZ was estimated to be 0.32 Gg y−1. Due to formidable data requirements, regional analysis may not easily be used to produce country-level estimates. However, regional analysis does provide a valuable benchmark against which the more straightforward IPCC methodology can be evaluated.

Pesticide residues in the aquatic environment of banana plantation areas in the North Atlantic Zone of Costa Rica

AbstractA study of pesticide residues in surface waters and sediments was undertaken in the Suerte River Basin, Costa Rica, that drains into the Tortuguero conservation area. Samples were collected in streams, packing plants, and the Suerte River. The most frequently measured compounds in surface water samples were the fungicides thiabendazole, propiconazole, and imazalil; the nematicides terbufos and cadusafos; and the insecticide chlorpyrifos. At the conservation area, propiconazole was detected in 43% of the samples at concentrations ranging from 0.05 to 1.0 μg/L. In 25% of the samples collected at this site, a nematicide (cadusafos, carbofuran, or ethoprophos) was detected (0.06–6.2 μg/L). According to this study, most of the insecticide‐nematicides analyzed pose a risk for acute or chronic toxicity to aquatic organisms based on the exposure levels and toxicity values from the literature. Ametryn, imazalil, and thiabendazole also exceeded the calculated chronic risk ratio. The most frequently detected compounds in sediments were thiabendazole, chlorpyrifos, imazalil, and propiconazole. The occurrence was higher in the packing plants and streams. Pesticides in waters and sediments of Tortuguero conservation area could pose a threat to this wetland and an additional stress to the endangered species that inhabit this area. More information is needed regarding the distribution and stability of pesticides in the lagoon system as well as of the effects of mixtures of low levels of pesticides and their degradation products on representative species of the Tortuguero ecosystem. Meanwhile, all measures to reduce the emissions of pesticides from the banana plantations and the packing plants should be taken.

Is there too much or too little natural forest in the Atlantic Zone of Costa Rica?

Deforestation rates in developing countries are often regarded as excessive, despite the lack of a satisfactory economic benchmark to evaluate this claim. This paper provides such a benchmark for a particular region in Costa Rica. The monetary value of the various functions performed by tropical rainforests is estimated and used in a conventional optimal control model to compute the globally optimal natural forest stock in the Atlantic Zone of Costa Rica. The results indicate that the current forest stock is suboptimally large, suggesting that promoting further forest conversion can increase economic welfare. The current stock would be near optimal only when (i) the annual benefits of carbon fixation are extremely high and (ii) the government of Costa Rica would be fully compensated for this positive externality.

Is there too much or too little natural forest in the Atlantic Zone of Costa Rica?

Deforestation rates in developing countries are often regarded as excessive, despite the lack of a satisfactory economic benchmark to evaluate this claim. This paper provides such a benchmark for a particular region in Costa Rica. The monetary value of the various functions performed by tropical rainforests is estimated and used in a conventional optimal control model to compute the globally optimal natural forest stock in the Atlantic Zone of Costa Rica. The results indicate that the current forest stock is suboptimally large, suggesting that promoting further forest conversion can increase economic welfare. The current stock would be near optimal only when (i) the annual benefits of carbon fixation are extremely high and (ii) the government of Costa Rica would be fully compensated for this positive externality.

A framework for integrated biophysical and economic land use analysis at different scales

There is a general need for quantitative tools that can be used to support policy makers in regional rural development. Here, a framework for (sub-) regional land use analysis is presented that quantifies biophysical and economic sustainability trade-offs. The framework, called sustainable options for land use (SOLUS), was developed over a 10-year period of investigation in the Northern Atlantic Zone of Costa Rica and encompasses scale levels that range from field to region. SOLUS consists of technical coefficient generators to quantify inputs and outputs of production systems, a linear programming model that selects production systems by optimizing regional economic surplus, and a geographic information system. Biophysical and economic disciplines are integrated and various types of knowledge, ranging from empirical expert judgement to deterministic process models are synthesized in a systems-analytical manner. Economic sustainability indicators include economic surplus and labor employment, and biophysical ones include soil N, P and K balances, biocide use and its environmental impact, greenhouse gas emission and nitrogen leaching loss and volatilization. Land use scenarios can be implemented by varying properties of production inputs (e.g., prices), imposing sustainability restrictions in the optimization, and incorporating alternative production systems based on different technologies. Examples of application of SOLUS in the Northern Atlantic Zone of Costa Rica show that introduction of alternative technologies may result in situations that satisfy both economic as well as biophysical sustainability. On the other hand, negative trade-offs were found among different dimensions of biophysical sustainability themselves.

Quantification of land use systems using technical coefficient generators: a case study for the Northern Atlantic zone of Costa Rica

This paper describes two generic so-called technical coefficient generators, PASTOR (Pasture and Animal System Technical coefficient generatOR) and LUCTOR (Land Use Crop Technical coefficient generatOR), that quantify land use systems in terms of inputs and outputs based on the integration of systems-analytical knowledge, standard agronomic and animal husbandry data and expert knowledge. PASTOR quantifies livestock systems while LUCTOR is geared towards cropping systems. Main inputs quantified include costs, labour requirements, fertiliser use and application of crop protection agents. Outputs are production and a number of associated environmental indicators. Although both PASTOR and LUCTOR were developed to generate input data for land use models, they are also useful as stand-alone tools to explore the technical efficiency of land use systems, to perform cost-benefit analyses and to quantify the trade-off among socio-economic, agronomic and environmental indicators at the field level. PASTOR and LUCTOR are illustrated with data from the Northern Atlantic zone in Costa Rica. Tools such as PASTOR and LUCTOR integrate different types of knowledge, including non-documented knowledge from field experts and make that knowledge transparent and open to critical review and discussion by others.