The Effect of Land-use on Nutrient Cycles of Tropical Streams on the Osa Peninsula, Costa Rica PDF Download
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Author: Kelly Bringhurst
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Languages : en
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The effect of land-use on nutrient cycles of tropical streams on the Osa Peninsula, Costa Rica: a paired catchment approach to investigate current conditions and projected changes. Kelly N. Bringhurst Abstract This study is concerned with potential environmental degradation of soils, rivers and coastal regions of the Osa Peninsula, Costa Rica due to deforestation. A paired, small-catchment approach to the study of environmental pressures on nutrient transfer and aquatic enrichment was used with one catchment that had been cleared for pasture (CN9) and the second primarily undisturbed tropical wet forest (CS 1). Nutrients and related parameters in soils and transferred in normal hydrological discharge were investigated. Soils in the study area are oxisols with concentrations of organic matter, total and plant available P higher in the forested catchment. Indirect measures of suspended sediment by turbidity showed an increase in the deforested catchment stream. Water input via rainfall for the year June 2008-June 2009 was approximately 5000 mm. Stream discharge was approximately 3300 mm year" for each catchment as measured by continuous recorders and evapotranspiration was, on average, 1500 mm year". These data suggested a good resolution of the water balance from independent measurements. The effect of deforestation on stream discharge was a 59% increase in flow during the wet season and an increase in the Q5:Q95 ratio showing that the deforested stream was flashier. Loss of forest canopy and decreased organic matter in the soil resulted in a depletion of available N. The deforested catchment loss of dissolved inorganic nitrogen (DIN) increased 33% over the forested catchment. Soluble reactive phosphorus (SRP) showed a 47% increase in the deforested catchment compared with the forested catchment. The molar N:P ratios were lower than expected and both streams were well below the 0.06 mg L-1 level at which N- limitation has been reported. Effects of nutrient loading have been observed through increased algal growth on equipment surfaces in the deforested catchment stream and increased nutrient yields will likely lead to eutrophication of coastal waters. Key Words - eutrophication, phosphorus, nitrogen, suspended sediment, deforestation, tropical forest.
Author: Kelly Bringhurst
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The effect of land-use on nutrient cycles of tropical streams on the Osa Peninsula, Costa Rica: a paired catchment approach to investigate current conditions and projected changes. Kelly N. Bringhurst Abstract This study is concerned with potential environmental degradation of soils, rivers and coastal regions of the Osa Peninsula, Costa Rica due to deforestation. A paired, small-catchment approach to the study of environmental pressures on nutrient transfer and aquatic enrichment was used with one catchment that had been cleared for pasture (CN9) and the second primarily undisturbed tropical wet forest (CS 1). Nutrients and related parameters in soils and transferred in normal hydrological discharge were investigated. Soils in the study area are oxisols with concentrations of organic matter, total and plant available P higher in the forested catchment. Indirect measures of suspended sediment by turbidity showed an increase in the deforested catchment stream. Water input via rainfall for the year June 2008-June 2009 was approximately 5000 mm. Stream discharge was approximately 3300 mm year" for each catchment as measured by continuous recorders and evapotranspiration was, on average, 1500 mm year". These data suggested a good resolution of the water balance from independent measurements. The effect of deforestation on stream discharge was a 59% increase in flow during the wet season and an increase in the Q5:Q95 ratio showing that the deforested stream was flashier. Loss of forest canopy and decreased organic matter in the soil resulted in a depletion of available N. The deforested catchment loss of dissolved inorganic nitrogen (DIN) increased 33% over the forested catchment. Soluble reactive phosphorus (SRP) showed a 47% increase in the deforested catchment compared with the forested catchment. The molar N:P ratios were lower than expected and both streams were well below the 0.06 mg L-1 level at which N- limitation has been reported. Effects of nutrient loading have been observed through increased algal growth on equipment surfaces in the deforested catchment stream and increased nutrient yields will likely lead to eutrophication of coastal waters. Key Words - eutrophication, phosphorus, nitrogen, suspended sediment, deforestation, tropical forest.
Author: Nathan M. Geller
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Category :
Languages : en
Pages : 0
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Author: Mary J. Jawlik
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Category :
Languages : en
Pages : 62
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Author: Sam Gerrits
Publisher: Bib. Orton IICA / CATIE
ISBN:
Category :
Languages : en
Pages : 312
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Author: Lindsay Hagamen
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Category :
Languages : en
Pages : 39
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Author: Abigail Alexandra Hewitt
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Category :
Languages : en
Pages : 0
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Author: Michael R. Monfredi
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Category : Fish communities
Languages : en
Pages : 116
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The geologic past of what we now know as Central America has provided a favorable and interesting history for the development of high levels of biological diversity currently observed. One of the most biologically diverse countries here is Costa Rica, which possesses greater richness values than five of the other Central American countries in birds, amphibians, and fishes, and has the greatest number of known plant species as of the year 2000. In order to better understand the current state of fish communities across the southwestern region of Costa Rica, I set out to accomplish three main goals: 1) to provide a more extensive understanding of stream fish communities throughout Osa and nearby mainland Costa Rica, and how they are influenced by abiotic and physical factors, 2) to compare individual species morphometry across streams influenced by a variety of physical and abiotic factors to determine the potential affect of those factors on fish size relationships, and 3) to compare freshwater fish communities, and individual species morphology, in pristine conditions with those communities/individuals present in a variety of surrounding land use patterns (e.g. agricultural lands, cattle ranches, and rural areas). The characid Astyanax aeneus (37%), gobies Awaous transandeanus (9%) and Sicydium salvini (8.7%), and poecilid Poecilia gilli (8.5%) were the most abundant species collected/observed. Canonical correspondence analysis revealed that four main factors are influencing community composition; namely distance from ocean, current land-use type, geologic history, and canopy cover. Furthermore, I found statistical differences in overall community structure between different land-use types as well as different geological landmasses. In regards to species morphometry, stream physical characteristics (i.e. distance from ocean, temperature, percent canopy cover, and geologic region), accompanied by differing surrounding land-use patterns, were found to be significantly related to either overall sizes or size allometric relationships, or both, among five species from the Osa Peninsula and neighboring mainland in Costa Rica. I conclude that this research provides an intricate knowledge of tropical stream fish communities throughout southwestern Costa Rica; however, broader reaching impacts were also achieved as this research can be used as either a model for further study design or as a basis for comparison with other tropical or temperate stream communities.
Author: Andrew John Skrinyer
Publisher:
ISBN:
Category : Atelidae
Languages : en
Pages : 60
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Tropical rainforests are critical to continued human existence on Earth. Carbon sequestration, the global hydrological cycle, and medicinal plants are best provided by large tracts of intact rainforest. Unfortunately, forest loss is prevalent throughout the tropics, which house the world’s most biodiverse ecosystems. I conducted an assessment of standing forest health and a primate census at the Piro Biological Station on the Osa Peninsula, Costa Rica over a 6-week period in 2014. I characterized edge effects throughout the forest in relation to land cover types that border the forest edge, compared edge-to-interior forest at the site, and related these data to the distribution of four primate species (Ateles geoffroyi, Saimiri oerstedii, Alouatta palliata, and Cebus capucinus) found there. My results and satellite imagery suggest that this area is currently undergoing a period of forest regeneration. Likewise, a primate census revealed that Ateles geoffroyi, listed as Endangered by the IUCN Red List, is abundant throughout the site, equally utilizing both edge and interior forest during the wet season. Since the nearby Corcovado National Park is known for its abundant Ateles geoffroyi population, this study reinforces the possibility of habitat corridors between Piro and Corcovado.
Author: Christopher M. Lorion
Publisher:
ISBN:
Category : Deforestation
Languages : en
Pages : 264
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Freshwater biodiversity in the tropics is threatened by a variety of anthropogenic factors, and land cover change may have the most widespread and pervasive impacts. Costa Rica has experienced extensive deforestation, and there is a great need to understand how land cover change has affected stream ecosystems and investigate strategies for mitigating these impacts. Understanding the distribution of freshwater biodiversity in relatively pristine systems is also critical for effective conservation planning. To examine the effects of deforestation on stream communities in southeastern Costa Rica and test the hypothesis that riparian forest buffers can reduce these effects, comparisons were made between forested stream reaches and stream reaches adjacent to pasture with and without a riparian forest buffer. Based on these comparisons, deforestation appeared to significantly alter the diversity and taxonomic composition of fish and benthic macroinvertebrate assemblages in the study streams, as well as stream temperatures and allochthonous inputs. Reaches with a riparian forest buffer, however, generally maintained aquatic assemblages and stream ecosystem conditions more similar to those observed in forested reaches. Overall, these results provide support for existing Costa Rican regulations mandating riparian forest protection, and suggest that appropriate riparian management could significantly reduce the impacts of deforestation on tropical stream biota. To investigate landscape-scale patterns in fish diversity, stream fishes were sampled along an altitudinal gradient of nearly 500 m in the Sixaola River basin. Fish diversity decreased steeply with increasing elevation, and the main gradient in assemblage structure was strongly correlated with several stream habitat variables. Diadromous fishes were common throughout the altitudinal gradient and dominated the highest elevation sites, highlighting the importance of longitudinal connectivity in Mesoamerican river systems. Systematic conservation planning that focuses on terrestrial and aquatic ecosystems, as well as biophysical linkages between these realms, could potentially identify more efficient and effective reserve networks. A critical evaluation of existing planning methods illustrates how incorporating linkages among ecosystems increases planning complexity. Several of the methods reviewed would be applicable to an example planning domain in Costa Rica and Panama, but new tools will be needed to realize the full potential of a comprehensive planning approach.
Author: Ryan Toohey
Publisher:
ISBN:
Category : Watershed hydrology
Languages : en
Pages : 374
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Costa Rica experienced large scale deforestation between the 1940s and 1980s. Due to the rapid loss of forest, the Costa Rican government initiated the Pagos para Servicios Ambientales, or Environmental Service Payments (ESPs), program that linked ecosystem services such as biodiversity conservation and hydrological services to forested land cover by compensating private landowners for forest preservation, regeneration, or agroforestry activities. However, the effect of land use on hydrological services and processes remains an area of active research. Within the framework of the ESPs, this research investigated: 1) understanding the regional tropical hydrology, 2) determining whether regional land uses impact soil characteristics and hydrological processes, and 3) evaluating the significance and overlap of different ecosystem services within the context of conservation planning. In the first chapter, I measured soil properties and hydrological processes within common regional land uses (forest, coffee, sugar cane and pasture) at the point, the plot, and the field scales. Macropore networks facilitated much more percolation in the forest and coffee. Compaction in the sugar and pasture diverted precipitation horizontally as surface runoff and lateral flow. In Chapter 2, I investigated whether similar results could he observed at greater scales using one-cell and watershed model simulations based on the Soil Moisture Routing model. I combined land use parameterization to investigate the interplay of antecedent moisture content (AMC), infiltration, surface runoff and percolation using a one-cell model. At this scale, a 'fill and spill' runoff generation mechanism was observed when precipitation intensity exceeded the different land use soil storage amounts and conductivities. The greatest differences between land uses were observed at AMC less than field capacity where subsurface connectivity was limited within the sugar and pasture. Seven nested watersheds were classified as either forested (>85% forested) or mixed-land use watersheds (
