Soil C/N ratios cause opposing effects in forests compared to grasslands on decomposition rates and stabilization factors in southern European ecosystems.

Soils store an important amount of carbon (C), mostly in the form of organic matter in different decomposing stages. Hence, understanding the factors that rule the rates at which decomposed organic matter is incorporated into the soil is paramount to better understand how C stocks will vary under changing atmospheric and land use conditions. We studied the interactions between vegetation cover, climate and soil factors using the Tea Bag Index in 16 different ecosystems (eight forests, eight grasslands) along two contrasting gradients in the Spanish province of Navarre (SW Europe). Such arrangement encompassed a range of four climate types, elevations from 80 to 1420 m.a.s.l., and precipitation (P) from 427 to 1881 mm year-1. After incubating tea bags during the spring of 2017, we identified strong interactions between vegetation cover type, soil C/N and precipitation affecting decomposition rates and stabilization factors. In both forests and grasslands, increasing precipitation increased decomposition rates (k) but also the litter stabilization factor (S). In forests, however, increasing the soil C/N ratio raised decomposition rates and the litter stabilization factor, while in grasslands higher C/N ratios caused the opposite effects. In addition, soil pH and N also affected decomposition rates positively, but for these factors no differences between ecosystem types were found. Our results demonstrate that soil C flows are altered by complex site-dependent and site-independent environmental factors, and that increased ecosystem lignification will significantly change C flows, likely increasing decomposition rates in the short term but also increasing the inhibiting factors that stabilize labile litter compounds.

Thinning affects nutrient resorption and nutrient-use efficiency in two Pinus sylvestris stands in the Pyrenees.

Needle chemical composition was measured, and nutrient resorption, nutrient-use efficiency (NUE), and other indexes were estimated for 24 months in two contrasting natural Pinus sylvestris L. forests in the western Pyrenees in Spain. For each location (Aspurz, 650 m elevation, 7% slope; Garde, 1335 m elevation, 40% slope), there were three reference plots (P0), three plots with 20% of the basal area removed (P20), and three with 30% of the basal area removed (P30). Needle P, Ca, and Mg concentrations were higher in Garde, but N concentration was higher for Aspurz, without differences for K. Nutrient-resorption efficiency of P was higher in Aspurz, of Mg higher in Garde, and there were no differences between sites in N and K. Nutrient-resorption proficiency was significantly higher in the site with lower soil nutrient availability, i.e., for P, Ca, and Mg in Aspurz, but N in Garde (no differences in K); this may be an indicator of nutrient conservation strategy. Annual nutrient productivity (A) was higher for all nutrients in Aspurz, whereas the mean residence time (MRT) was higher in Garde in all nutrients but P. NUE was significantly higher in Garde for all nutrients but P, which was more efficiently used in Aspurz. In both sites, N, P, and K concentrations were higher in the 2002 cohort, Ca in the 2000 cohort, and maximum Mg was found in the 2001 cohort. Thinning caused a reduction of Mg concentration in the 2001 cohort in Aspurz, an increase of Ca resorption proficiency in Aspurz and Mg resorption at both sites, and reduction of P, K, and Mg nutrient response efficiency (NRE) in Garde. Thinning may have caused an increase of the C:Mg ratio through facilitating the development of more biosynthesis apparatus in a more illuminated canopy, but it seemed not to affect resorption in a significant way. Changes in NRE in Garde after thinning show that forest management can affect how trees use nutrients. Our results indicate that the strategy to optimize NUE is different in each stand. In Aspurz (a Mediterranean ecosystem), pine trees carried out resorption more efficiently, while in Garde (a continental forest), trees used nutrients for longer periods of time and reduced their efficiency in using the available soil nutrients after reduced competition by thinning.

El óxido nítrico como nuevo sistema en la farmacología del estrés / Nitric oxide as a new system in the pharmacology of stress

El propósito de esta publicación es presentar evidencias científicas publicadas que confirman que el óxido nítrico (NO) participa activamente en la reacción del estrés y en los mecanismos genéticos de la adaptación. El NO se sintetiza a partir de la Larginina por la sintasa de óxido nítrico (NOS) y participa en un gran número de procesos fisiológicos: trasmisión de la señal en el cerebro, regulación del sistema cardiovascular, inmune, gastrointestinal y urogenital. Desde 1990, muchas evidencias indican que el NO participa en la regulación del aparato genético; y ahora existen muchos datos que muestran que los factores estresantes ambientales aumentan la producción de NO, lo cual sugiere que el incremento de la producción de NO es la respuesta del organismo a la reacción del estrés. Malyshev y Manuklina, en base al postulado de Meerson, definen al sistema de generación del NO como un nuevo nuevo sistema, nitroérgico, limitante del estrés en los humanos y animales, con las siguientes características: 1) se induce por el estrés, 2) es capaz de limitar la reacción de estrés, 3) tiene la capacidad de aumentar la resistencia a los factores ambientales, 4) la capacidad del NO de aumentar y de los inhibidores de la NOS a disminuir la resistencia al estrés y la adaptación de los organismos; y 5) capacidad para aumentar su actividad en el proceso de adaptación. Este nuevo escenario nos permite visionar un futuro promisorio en la investigación y desarrollo de medicamentos a base de plantas medicinales con propiedades de modular el sistema generador del NO; al mismo tiempo que hacemos las siguientes reflexiones: 1) ¿se puede utilizar al NO como un indicador del estrés?, si así fuera, 2) ¿se puede desarrollar alguna técnica apropiada para esta determinación? y, 3) ¿seremos capaces de percibir esta nueva oportunidad terapéutica para un mejor aprovechamiento de las plantas medicinales y los productos naturales?.

The intention of this publication is to present published scientific evidences that confirm that the nitric oxide (NO) actively participates in stress and the adaptation. NO is synthesized in the organism from L-arginine by the enzyme NO-synthase. NO participates in a great number of physiological processes: signal transmisision in the brain, regulation of cardiovascular, immune, gastrointestinal and urogenital systems. From the early 1990s very important proofs have appeared indicating that NO is involved in the regulation of genetic apparatus; and there is a lot of information that show that the stressful environmental factors increased the production of NO, it can be suggested that the increased NO production is a response of the organism to stress reaction. Malyshev and Manuklina, on the basis of Meerson’s postulate, define to the system of generation of NO as a newly recognized the NO-ergic stress-limiting system in the human beings and animals, with the following characteristics: 1) stress-inducibility, 2) capability to limit the stress reaction, 3) capability to increase the resistance to environmental factors, 4) capability of NO to increased and NO-synthase inhibitors to decrease the ressistance to stress and adaptability of the organism, and 5) capability to increase its activity in the process of adaptation. This information allows us visionar a promissory future in the search of medicines from medicinal plants capable of modulating the generating system of NO. Finally, we do the following reflections: 1) is it possible to use to NO as an indicator of the stress?, if this way out, 2) is it possible to develop some technology adapted for this determination? And, 3) will we be capable of taking advantage of this new therapeutic opportunity for the medicinal plants and the natural products?.

La selva amazónica como fuente de pigmentos naturales para la avicultura mundial / The amazonian jungle as a source of natural pigments for the world aviculture

Las investigaciones etnofarmacológicas que estamos llevando a cabo desde hace varios años en la selva del Perú nos ha permitido plantear la hipótesis que las plantas utilizadas por los nativos para pigmentar su cuerpo, también pueden ser utilizadas para pigmentar la piel de los pollos de carne y la yema del huevo cuando son utilizdos por vía interna. Después de un adecuado screening hemos seleccionado algunas plantas que han demostrado in vivo estas propiedades (efectividad). No se trata de la Curcuma longa (palillo), Bixa orellana (achiote), tampoco de la Tagetes sp. (marigold). Se trata de especies que además, se usan ampliamente por sus propiedades medicinales (seguridad) y que contienen componentes bioactivos con estructuras químicas hidro y liposolubles lo cual hace que su efecto en la piel del ave se aprecie en pocos días (economía). Todo lo cual es muy ventajoso en comparación con las xantofilas que se vienen usando en la avicultura mundial. Los ensayos se estan realizando en la costa, sierra y selva con resultados muy alentadores; sin embargo, el no contar con un laboratorio adecuadamente equipado está dificultando el desarrollo de estos nuevos pigmentantes. Le correspode a la empresa privada involucrarse en esta iniciativa científica para poder acceder con ventaja competitiva a un gran mercado que tiene crecimiento sostenido.