La respuesta compensatoria de Pentaclethra macroloba ante tratamientos antagónicos: la fertilización y la defoliación

2019 ◽  
Author(s):  
Alejandra Pérez Enríquez ◽  
Roberto Cordero ◽  
Elizabeth Braker
Keyword(s):  
Costa Rica ◽  
Pentaclethra Macroloba

La combinación de rasgos como la fijación de nitrógeno en plantas tropicales con otros rasgos como disponibilidad nutricional podría incidir en el éxito de algunas especies para su establecimiento y desarrollo. Otras interacciones como la herbivoría podrían cambiar sutilmente estas relaciones y llegar a ser relevantes para su éxito ecológico. Sometimos brinzales de Pentaclethra macroloba (Gavilán, Fabaceae) en macetas, con y sin adición de nutrientes y a la interacción con defoliación controlada (herbivoría artificial), en el sotobosque secundario dentro de un bosque de Sarapiquí, Costa Rica. La biomasa total muestra una fuerte compensación neta y la defoliación indujo una mayor asignación al follaje. La fertilización siempre resultó en menos asignación a nódulos. La esbeltez respondió a ambos factores de manera sinergística. Sugerimos que la herbivoría puede ocasionar cambios importantes en la manera en que las especies asignan sus recursos en concordancia con sus simbiosis y la disponibilidad de nutrientes.

Effects of light regime on the growth and physiology of Pentaclethra macroloba (Mimosaceae) in Costa Rica

1985 ◽  
Vol 1 (4) ◽  
pp. 303-320 ◽  
Author(s):  
Steven F. Oberbauer ◽  
Boyd R. Strain
Keyword(s):  
Costa Rica ◽  
Stomatal Density ◽  
Structural Characteristics ◽  
Sudden Change ◽  
Light Level ◽  
Leaf Damage ◽  
Growth Responses ◽  
Pentaclethra Macroloba ◽  
Partial Shade ◽  
Treefall Gap

ABSTRACTSeedlings of Pentaclethra macroloba (Willd.) Kuntze, a dominant, shade-tolerant species of tropical moist forest in Costa Rica, were raised under three light conditions to assess their acclimatization and growth responses to irradiance. The light environments used were full sun, partial shade (25% of full sun), and full shade (1% of full sun). To test the effect of a sudden change in light level such as would occur in the event of a treefall gap, the seedlings in the above conditions were switched between environments after two months and grown for an additional 1.5 months. Plants in full sun and partial shade had similar total weight; switching between the two environments had no effect on biomass. Plants switched from full sun and partial shade to full shade had negative growth as a result of negative CO2, flux and leaf abscission. Plants transferred from full shade to full sun had lower growth rates than those switched from full shade to partial shade because of severe leaf damage in full sun. The previous environment significantly affected the response of most growth and size characteristics to the present environment. Maximum photosynthesis changed only 30% in response to light level during growth. However, large changes in other photosynthetic and structural characteristics were found. Leaves developed in full shade had lower respiration, leaf thickness, and stomatal density and higher apparent quantum yield, specific leaf area, and chlorophyll content than leaves from full sun. Osmotic potentials were similar between treatments. Despite only small changes in maximum photosynthesis, acclimatization to extreme shade or sun rendered leaves unsuitable for large changes in environment. Consequently, in the event of a large treefall gap, plants already present in the understory will require a substantial period of adjustment before they respond to the increase in light.

scholarly journals Influence of Two Important Leguminous Trees on Their Soil Microbiomes and Nitrogen Cycle Activities in a Primary and Recovering Secondary Forest in the Northern Zone of Costa Rica

Soil Systems ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 65
Author(s):  
William D. Eaton ◽  
Katie M. McGee ◽  
Elizabeth Hoke ◽  
Alex Lemenze ◽  
Mehrdad Hajibabaei
Keyword(s):  
Land Use ◽  
Costa Rica ◽  
Functional Groups ◽  
Forest Succession ◽  
Secondary Forest ◽  
Nodule Development ◽  
Land Use Impacts ◽  
N Cycle ◽  
Inga Edulis ◽  
Pentaclethra Macroloba

Inga edulis and Pentaclethra macroloba are dominant N-fixing forest trees in Costa Rica, likely important for recovery of soil N and C after deforestation, yet little is known of their soil microbiomes nor how land use impacts them. Soils from both trees in a primary and secondary forest were assessed for N-cycle metrics and DNA sequence-based composition of total bacterial, potential N-fixing bacterial, and potential ammonium oxidizing bacterial genera. The compositions of the functional groups of bacteria, but not their total relative abundance of DNA, were different across the soils. The P. macroloba soils had greater NO3− levels and richness of both functional groups, while I. edulis soils had greater NH4+ levels, consistent with its NH4+ preference for root nodule development. The bacterial communities were different by habitat, as secondary forest I. edulis microbiomes were less rich, more dominant, possibly more affected by the disturbance, or reached equilibrium status quicker than the richer, less dominant P. macroloba microbiomes, which may be developing slower along with secondary forest succession, or were less affected by the disturbance. Functional redundancy and switching of 10 N-cycle bacterial genera was evident between the primary and secondary forest soils, likely to maintain stable levels of N-cycle activity following disturbance. In summary, the two tree soil microbiomes are different, land use differentially affects them, and, thus, both tree species should be used during forest regeneration strategies in this region.

scholarly journals Percepción y decisión económica de productores locales: el rol del pago por servicios ambientales para dos tipos de bosque en la región Huetarnorte, Costa Rica

2010 ◽  
Vol 40 (2) ◽  
pp. 44
Author(s):  
Víctor Meza ◽  
Guillermo Navarro ◽  
Benno Pokorny
Keyword(s):  
Costa Rica ◽  
Carapa Guianensis ◽  
Pentaclethra Macroloba

<p>Se evaluó el comportamiento financiero de tres formatos de pago por servicios ambientales (PSA) sobre el valor del bosque (VB), a partir de una primera cosecha forestal en bosques clasificados en dos tipos, de acuerdo con la dominancia de Pentaclethra macroloba en combinación con palmas (Bosque Pp) o en combinación con Carapa guianensis (Bosque Pc). En estos bosques se construyeron funciones de producción típicas del manejo forestal sostenible (MFS) y de la rentabilidad para dos condiciones de cosecha durante un ciclo de corta. El resultado de estos valores del bosque demostró que ningún esquema actual de manejo forestal sostenible y/o de pago por servicios ambientales puede competir con los precios de los terrenos propuestos en el mercado ni con la elevada demanda y acumulación de tierras dedicadas a cultivos muy rentables. Complementariamente, se consideró la percepción de los productores locales hacia la compatibilidad del manejo forestal sostenible y el pago por servicios ambientales, junto con el valor del bosque, para establecer sus preferencias sobre determinados usos del suelo.</p>

δ13C in Pentaclethra macroloba trees growing at forest edges in north-eastern Costa Rica

2008 ◽  
Vol 24 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Jessica L. Schedlbauer ◽  
Kathleen L. Kavanagh
Keyword(s):  
Costa Rica ◽  
Soil Carbon ◽  
Edge Effects ◽  
Environmental Gradients ◽  
Forest Edges ◽  
Functional Responses ◽  
Isotopic Analyses ◽  
North Eastern ◽  
Pentaclethra Macroloba ◽  
Study Sites

AbstractFragmented forest landscapes with large proportions of edge area are common in the tropics, though little is known about functional responses of trees to edge effects. Foliar δ13C can increase our understanding of tree function, as these values reflect changes in ci/ca as trees respond to environmental gradients. We expected that foliar δ13C would be enriched, indicating a decline in ci/ca, in Pentaclethra macroloba trees growing at forest edges in north-eastern Costa Rica. We also anticipated this isotopic shift in δ13C values of soil carbon and soil respired CO2. Three transects perpendicular to forest edges were established at three study sites, and six plots per transect were located 0–300 m from edges. Within plots, foliage, soil and soil respired CO2 were collected for isotopic analyses. Foliar δ13C, thus ci/ca, and soil carbon δ13C did not vary along the edge to interior gradient. δ13C for canopy and understorey foliage averaged −29.7‰ and −32.5‰, respectively, while soil carbon δ13C averaged −28.0‰. Soil respired CO2 δ13C ranged from −29.2‰ to −28.6‰ and was significantly depleted within 50 m of edges. The predominant lack of functional responses at forest edges indicates that P. macroloba trees are robust and these forests are minimally influenced by edge effects.

Identification of Maize Rayado Fino Virus by Immunoelectron Microscopy

1985 ◽  
Vol 43 ◽  
pp. 636-637
Author(s):  
O. E. Bradfute
Keyword(s):  
Electron Microscopy ◽  
Zea Mays ◽  
Costa Rica ◽  
Severe Disease ◽  
Rabbit Serum ◽  
Normal Rabbit Serum ◽  
Virus Particles ◽  
Far North ◽  
Maize Rayado Fino Virus ◽  
Antibody Coating

Maize rayado fino virus (MRFV) causes a severe disease of corn (Zea mays) in many locations throughout the neotropics and as far north as southern U.S. MRFV particles detected by direct electron microscopy of negatively stained sap from infected leaves are not necessarily distinguishable from many other small isometric viruses infecting plants (Fig. 1).Immunosorbent trapping of virus particles on antibody-coated grids and the antibody coating or decoration of trapped virus particles, was used to confirm the identification of MRFV. Antiserum to MRFV was supplied by R. Gamez (Centro de Investigacion en Biologia Celular y Molecular, Universidad de Costa Rica, Ciudad Universitaria, Costa Rica).Virus particles, appearing as a continuous lawn, were trapped on grids coated with MRFV antiserum (Fig. 2-4). In contrast, virus particles were infrequently found on grids not exposed to antiserum or grids coated with normal rabbit serum (similar to Fig. 1). In Fig. 3, the appearance of the virus particles (isometric morphology, 30 nm diameter, stain penetration of some particles, and morphological subunits in other particles) is characteristic of negatively stained MRFV particles. Decoration or coating of these particles with MRFV antiserum confirms their identification as MRFV (Fig. 4).

Social representations of human rights violations: Further evidence

2001 ◽  
Vol 60 (2) ◽  
pp. 89-98 ◽  
Author(s):  
Alain Clémence ◽  
Thierry Devos ◽  
Willem Doise
Keyword(s):  
Cluster Analysis ◽  
Human Rights ◽  
Costa Rica ◽  
Young People ◽  
Social Representations ◽  
Social Reality ◽  
Questionnaire Study ◽  
Human Rights Violations ◽  
High Tolerance ◽  
Individual Actions

Social representations of human rights violations were investigated in a questionnaire study conducted in five countries (Costa Rica, France, Italy, Romania, and Switzerland) (N = 1239 young people). We were able to show that respondents organize their understanding of human rights violations in similar ways across nations. At the same time, systematic variations characterized opinions about human rights violations, and the structure of these variations was similar across national contexts. Differences in definitions of human rights violations were identified by a cluster analysis. A broader definition was related to critical attitudes toward governmental and institutional abuses of power, whereas a more restricted definition was rooted in a fatalistic conception of social reality, approval of social regulations, and greater tolerance for institutional infringements of privacy. An atypical definition was anchored either in a strong rejection of social regulations or in a strong condemnation of immoral individual actions linked with a high tolerance for governmental interference. These findings support the idea that contrasting definitions of human rights coexist and that these definitions are underpinned by a set of beliefs regarding the relationships between individuals and institutions.

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