Lixiviación de nutrimentos principales en cuatro sistemas agroforestales con cultivos perennes de Turrialba, Costa Rica

Tesis (M. Sc) -- CATIE; UCR, Turrialba (Costa Rica), 1987Los tratamientos fueron el tipo de árboles, el tipo de cultivos, la interacción árboles por cultivos y las épocas de muestreo. Como covariables se incluyeron el ingreso de nitrógeno al mantillo a través de la hojarasca, las precipitaciones en el período anterior al considerado, la época de poda y/o fertilización y la distancia del punto de muestreo a los árboles más cercanos. El análisis de las covariables mostró que no existen efectos atribuibles al nitrógeno incorporado al mantillo con la hojarasca sobre la lixiviación de nutrimentos, lo cual resulta de interés en el análisis de la función de las leguminosas en estos sistemas. Se concluyó, además, que la circulación de nutrimentos en los sistemas agroforestales estudiados es muy eficiente, lo que constituye un aspecto muy favorable para la sostenibilidad productiva y ecológica de los mismos

Techo productivo regional y de las fincas del ?rea de Jocoro, El Salvador: estudio econ?mico y ambiental de alternativas de Producci?n mediante modelos en simulaci?n

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An?lisis y perspectivas del manejo forestal en concesiones comunitarias, Pet?n, Guatemala

3 ilus. 8 tab. 23 ref

Ponencias y comunicaciones. V.1. El medio forestal

6 tab. 25 ref. Sum. (En, Es)Se estudi?, durante el per?odo de Octubre/89 a Junio/90, la tasa de descomposici?n, la liberaci?n de nutrientes (N, P, K, Ca y Mg) y el cambio en la pared celular de la hojarasca natural. El estudio comprendi? las parcelas agroforestales con cultivos perennes: caf? (Coffea arabica) asociado con ?rboles leguminosas de sombra, por? (Erythrina poeppigiana) caf? con ?rboles maderables de sombra laurel (Cordia alliodora) cacao (Theobroma cacao) con por? y cacao con laurel, en un dise?o de bloques completos al azar con parcelas divididas ("split plot", caf? o cacao). La hojarasca del sistema cacao/laurel present? una descomposici?n lenta, la p?rdida fue de apenas 32 por ciento del peso inicial. La hojarasca de los sistemas cacao/por?, caf?/laurel y caf?/por? present? p?rdidas m?s r?pidas: 47, 49 y 58 por ciento, respectivamente. Aparentemente, los factores que contribuyeron m?s claramente a estas diferencias fueron las caracter?sticas f?sico-qu?micas de la hojarasca. El patr?n de liberaci?n de N es similar y el P es mayor a la p?rdida de peso seco. El Ca present? patr?n de liberaci?n m?s lento que el peso seco, mientras que el K se liber? m?s r?pidamente y el Mg present? un patr?n similar a la p?rdida de peso seco

On the ability of a global atmospheric inversion to constrain variations of CO2 fluxes over Amazonia

The exchanges of carbon, water and energy between the atmosphere and the Amazon basin have global implications for the current and future climate. Here, the global atmospheric inversion system of the Monitoring of Atmospheric Composition and Climate (MACC) service is used to study the seasonal and interannual variations of biogenic CO2 fluxes in Amazonia during the period 2002?2010. The system assimilated surface measurements of atmospheric CO2 mole fractions made at more than 100 sites over the globe into an atmospheric transport model. The present study adds measurements from four surface stations located in tropical South America, a region poorly covered by CO2 observations. The estimates of net ecosystem exchange (NEE) optimized by the inversion are compared to an independent estimate of NEE upscaled from eddy-covariance flux measurements in Amazonia. They are also qualitatively evaluated against reports on the seasonal and interannual variations of the land sink in South America from the scientific literature. We attempt at assessing the impact on NEE of the strong droughts in 2005 and 2010 (due to severe and longer-thanusual dry seasons) and the extreme rainfall conditions registered in 2009. The spatial variations of the seasonal and interannual variability of optimized NEE are also investigated. While the inversion supports the assumption of strong spatial heterogeneity of these variations, the results reveal critical limitations of the coarse-resolution transport model, the surface observation network in South America during the recent years and the present knowledge of modelling uncertainties in South America that prevent our inversion from capturing the seasonal patterns of fluxes across Amazonia. However, some patterns from the inversion seem consistent with the anomaly of moisture conditions in 2009.The exchanges of carbon, water and energy be- tween the atmosphere and the Amazon basin have global im- plications for the current and future climate. Here, the global atmospheric inversion system of the Monitoring of Atmo- spheric Composition and Climate (MACC) service is used to study the seasonal and interannual variations of biogenic CO 2 fluxes in Amazonia during the period 2002?2010. The system assimilated surface measurements of atmospheric CO 2 mole fractions made at more than 100 sites over the globe into an atmospheric transport model. The present study adds measurements from four surface stations located in tropical South America, a region poorly covered by CO 2 ob- servations. The estimates of net ecosystem exchange (NEE) optimized by the inversion are compared to an independent estimate of NEE upscaled from eddy-covariance flux mea- surements in Amazonia. They are also qualitatively evaluated against reports on the seasonal and interannual variations of the land sink in South America from the scientific literature. We attempt at assessing the impact on NEE of the strong droughts in 2005 and 2010 (due to severe and longer-than- usual dry seasons) and the extreme rainfall conditions regis- tered in 2009. The spatial variations of the seasonal and in- terannual variability of optimized NEE are also investigated. While the inversion supports the assumption of strong spatial heterogeneity of these variations, the results reveal critical limitations of the coarse-resolution transport model, the sur- face observation network in South America during the recent years and the present knowledge of modelling uncertainties in South America that prevent our inversion from capturing the seasonal patterns of fluxes across Amazonia. However, some patterns from the inversion seem consistent with the anomaly of moisture conditions in 2009