47 research outputs found
Microhabitat heterogeneity promotes soil fertility and ground-dwelling arthropod diversity in Mediterranean wood-pastures
P. 192-201Mediterranean wood-pastures are extensive agroforestry systems that hold great ecological, social and cultural values, which consist of mixtures of grassland, scattered trees and shrubs, primarily used for livestock grazing. For centuries, low-intensity management in these landscapes has resulted in multiple microhabitats that favour biodiversity and are considered key elements for the long-term persistence of wood-pastures. However, the relative contribution of each microhabitat type to wood-pasture biodiversity and functioning remains poorly studied. We investigated the impact that different wood-pasture microhabitats have on soil chemical fertility and the decomposition food web. We analysed the two main microhabitats that make wood-pastures up – open grasslands and isolated trees – and three additional “litter-trapping” microhabitats – shrubs scattered in the grassland matrix, canopied shrubs and piles of pruning debris—in terms of soil chemical properties (organic matter content, total N, C:N ratio, available P, and exchangeable base cations), collembolan and dipteran (mostly detritivores) abundance, and carabid (seed-eaters and predators) and staphylinid (mostly predators) beetle abundance, body size, biomass, species richness and composition. Grasslands were the most different microhabitats, with the lowest soil nutrient content and particular carabid and staphylinid species composition. Trees had the highest soil fertility levels and abundance of Diptera and staphylinids, and held unique staphylinid assemblages. “Litter-trapping” microhabitats had medium to high soil nutrient values and shared a distinct staphylinid assemblage compared to grasslands and trees. Besides, scattered shrubs provided shelter for large-sized carabid and staphylinid predators, while canopied shrubs held the highest carabid abundance and biomass. “Litter-trapping” microhabitats retained tree leaves that would otherwise be lost to the wood-pasture, recovering nutrients to the system, and provided new habitat, shelter and food for detritivores and unique predator assemblages. “Litter-trapping” microhabitats thus enhanced soil fertility and the decomposition process, at the same time as increased the abundance and diversity of the communities of ground-dwelling detritivores and predators inhabiting wood-pastures. These findings confirmed that microhabitat heterogeneity resulting from low-intensity management is essential to maintain both the primary production and the biodiversity conservation value of wood-pastures.S
Soil-plant relationship in Calluna heathlands after experimental burning and nitrogen fertilization, studies from NW Spain
[EN] We studied changes in the relationship between soil nutrient content and plant species richness in Calluna heathlands after seven years of experimental burning (B) and nitrogen fertilization (NF). Our results indicate that both the treatments (B, NF, B+NF) and modification of several soil characteristics (total N, available Na, and C:N ratio) reflected in a significant increase in plant species richnessS
Disruption of trophic interactions involving the heather beetle by atmospheric nitrogen deposition
P. 436-445Elevated nitrogen (N) deposition impacts the structure and functioning of heathland ecosystems across Europe. Calluna plants under high N-inputs are very sensitive to secondary stress factors, including defoliation attacks by the heather beetle. These attacks result in serious damage or death of Calluna, its rapid replacement by grasses, and the subsequent loss of heathland. We know very little about the mechanisms that control the populations and trigger outbreaks of the heather beetle, impeding proper management measures to mitigate the damage. We investigated the effects of N deposition on the relationships between the heather beetle, its host plant, and two arthropod predators at building (rejuvenated through fire) and mature heathlands. The study combines field manipulation experiments simulating a range of N deposition rates (0, 1, 2, 5 g N m−2 year−1 for 2 years, and 5.6 g N m−2 year−1 for 10 years), and food-choice laboratory experiments testing the preferences of adults and larvae of the heather beetle for N-treated Calluna plants, and the preferences of predators for larvae grown on plants with different N-content. The larvae of the heather beetle achieved the highest abundances after the long-term (10-year) addition of N at mature Calluna plots in the field. Contrary to the adults, the larvae foraged preferentially on the most N-rich Calluna shoots under laboratory conditions. Predators showed no aggregative numerical responses to the accumulation of heather beetle larvae at high N-input experimental plots. During the feeding trials, predators consumed a small number of larvae, both in total and per individual, and systematically avoided eating the larvae reared on high-N Calluna shoots. Our study showed that the most severe defoliation damage by the heather beetle is inflicted at the larval stage under prolonged availability of high-N inputs, and that arthropod predators might not act as effective regulators of the beetle's populations.S
Provenance and seed mass determine seed tolerance 5 to high temperatures associated to forest fires in Pinus pinaster
P. 381-391We show that Pinus pinaster provenance
affects both seed germination and seedling recruitment
after fire. This information is crucial for managers to select
the best seed-provisioning populations when
implementing reforestation programs to assist the natural
post-fire regeneration of the speciesS
Plant and vegetation functional responses to cumulative high nitrogen deposition in rear-edge heathlands
P. 980-990Elevated atmospheric nitrogen (N) deposition is a major driver of change, altering the structure/functioning of nutrient-poor Calluna vulgaris-heathlands over Europe. These effects amply proven for north-western/central heathlands may, however, vary across the ecosystem's distribution, especially at the range limits, as heathlands are highly vulnerable to land-use changes combined with present climate change. This is an often overlooked and greatly understudied aspect of the ecology of heathlands facing global change. We investigated the effects of five N-fertilisation treatments simulating a range of N deposition rates (0, 10, 20, and 50 kg N ha−1 yr−1 for 1 year; and 56 kg N ha−1 yr−1 for 9 years) on the Calluna-plants, the plant functional groups, species composition and richness of two life-cycle stages (building/young- and mature-phase) of Calluna-heathlands at their rear-edge limit. Our findings revealed a dose-related response of the shoot length and number of flowers of young and mature Calluna-plants to the addition of N, adhering to the findings from other heathland locations. However, cumulative high-N loading reduced the annual growth and flowering of young plants, showing early signs of N saturation. The different plant functional groups showed contrasting responses to the cumulative addition of N: annual/perennial forbs and annual graminoids increased with quite low values; perennial graminoids were rather abundant in young heathlands but only slightly augmented in mature ones; while bryophytes and lichens strongly declined at the two heathland life-cycle stages. Meanwhile there were no significant N-driven changes in plant species composition and richness. Our results demonstrated that Calluna-heathlands at their low-latitude distribution limit are moderately resistant to cumulative high-N loading. As north-western/central European heathlands under high-N inputs broadly experienced the loss of plant diversity and pronounced changes in plant species dominance, rear-edge locations may be of critical importance to unravel the mechanisms of heathland resilience to future global change.S
Interactions between large high-severity fires and salvage logging on a short return interval reduce the regrowth of fire-prone serotinous forests
P. 54-63New fire disturbance regimes under accelerating global environmental change can have unprecedented consequences for ecosystem resilience, lessening ecosystem natural regeneration. In the Mediterranean Basin, fire-dependent obligate seeder forests that are prone to increasingly frequent stand-replacing fires and then salvaged logged repeatedly can be vulnerable to additional disturbances for decades. In this study, we investigated, for the first time, the cumulative and interactive effects of two large high-severity fires at a short (<15-year) return interval and the subsequent burned timber harvesting with biomass removal on the post-disturbance recovery of such forests. We further assessed the type and amount of the material legacies (deadwood) that persisted through the different post-disturbance successional trajectories, as well as the influence of these legacies on forest regeneration. The early recovery of the studied forests after two consecutive large fires and post-fire logging was, in the first place, driven by fire repetition, which led to reduced seedling recruitment and enhanced regrowth of resprouter shrubs. Despite no interactive effects between fire and logging were detected after a single large fire event, two repeated fires followed by salvage harvesting had a greater negative impact than two fires alone (synergistic effects) on seedling establishment; while a lower positive impact (subadditive effects) on the recovery of resprouter shrubs. There was also an interaction modification effect in which fire repetition worsened the per-unit impact of salvage logging on forest regeneration. Nonetheless, the residual legacies, i.e., fine and coarse woody debris (unburned needles, downed branches, pieces of deadwood, and burned pine cones) that remained after the manual harvesting of the burned trees, aided seedling re-establishment and hindered the regrowth of the shrubby understorey. These findings indicate that high-intensity salvage logging after two large high-severity fires at a short return interval is inadvisable in fire-prone serotinous pine forests, unless it explicitly retains the key material legacies that help tree natural regeneration and enhance ecosystem resilience to the next disturbance.S
Estudio de factibilidad para la creación de una empresa comercializadora de rosas de exportación para los mercados de Rusia y Ucrania, ubicada en la ciudad de Cayambe provincia de Pichincha
El presente trabajo de grado, consiste en la formulación de un estudio técnico – económico que está estructurado en siete capítulos.
El primer capítulo se refiere al diagnóstico geográfico de la zona de Cayambe, aquí se detallan: la población, extensión, lugares turísticos, tradiciones, comidas típicas, producción y actividad económica del cantón.
El segundo capítulo hace referencia a los fundamentos teóricos que sustentan el desarrollo de este proyecto, como es la parte: administrativa, empresarial, contable, surgimiento de las empresas florícolas en el cantón y sus alrededores, también hacemos énfasis en las exportaciones y las relaciones comerciales entre Ecuador – Rusia y Ecuador - Ucrania.
En el tercer capítulo, trata sobre el estudio de mercado, en el cual se describe el objetivo general y especifico del mismo, se realiza la identificación del producto, la aplicación de encuestas a los clientes y posibles proveedores de rosas con la respectiva tabulación e interpretación de resultados lo que da lugar al comportamiento de la oferta y demanda
El cuarto capítulo hace referencia al estudio técnico del proyecto, donde se describe la macro localización y micro localización de la planta de proceso, el diseño de las instalaciones y su distribución física, flujogramas de actividades de las áreas de ventas y postcosecha, requerimientos de personal administrativo, ventas y operativo, herramientas y equipos a utilizarse en el proceso y la capacidad de producción de la nueva unidad.
El quinto capítulo presenta la inversión y financiamiento necesario, para emprender el desarrollo del proyecto, se detallan las inversiones fijas, diferidas, capital de trabajo y amortización de la deuda, determinación de costo de producción, estado de resultados y se hace referencia a la evaluación económica del proyecto a través del análisis financiero del VAN, TIR, CB, PRI.
El sexto capítulo es la organización de la empresa con su respectivo marco legal, planificación estratégica, organigrama y manual de funciones; los mismos que son aspectos vitales para el buen desempeño y desarrollo de la empresa.
El séptimo capítulo se refiere a los impactos que originará el desarrollo de este proyecto como son: impacto social, económico, empresarial y ambiental.
Finalmente las conclusiones y recomendaciones acerca del trabajo de investigación
Remote sensing applied to the study of fire regime attributes and their influence on post-fire greenness recovery in pine ecosystems
Producción CientíficaWe aimed to analyze the relationship between fire regime attributes and the post-fire greenness recovery of fire-prone pine ecosystems over the short (2-year) and medium (5-year) term after a large wildfire, using both a single and a combined fire regime attribute approach. We characterized the spatial (fire size), temporal (number of fires, fire recurrence, and return interval), and magnitude (burn severity of the last fire) fire regime attributes throughout a 40-year period with a long-time series of Landsat imagery and ancillary data. The burn severity of the last fire was measured by the dNBR (difference of the Normalized Burn Ratio) spectral index, and classified according to the ground reference values of the CBI (Composite Burn Index). Post-fire greenness recovery was obtained through the difference of the NDVI (Normalized Difference Vegetation Index) between pre- and post-fire Landsat scenes. The relationship between fire regime attributes (single attributes: fire recurrence, fire return interval, and burn severity; combined attributes: fire recurrence-burn severity and fire return interval-burn severity) and post-fire greenness recovery was evaluated using linear models. The results indicated that all the single and combined attributes significantly affected greenness recovery. The single attribute approach showed that high recurrence, short return interval and low severity situations had the highest vegetation greenness recovery. The combined attribute approach allowed us to identify a wider variety of post-fire greenness recovery situations than the single attribute one. Over the short term, high recurrence as well as short return interval scenarios showed the best post-fire greenness recovery independently of burn severity, while over the medium term, high recurrence combined with low severity was the most recovered scenario. This novel combined attribute approach (temporal plus magnitude) could be of great value to forest managers in the development of post-fire restoration strategies to promote vegetation recovery in fire-prone pine ecosystems in the Mediterranean Basin under complex fire regime scenarios.Ministerio de Economía y Competitividad, y el Fondo Europeo de Desarrollo Regional (FEDER), en el marco del GESFIRE (AGL2013-48189-C2-1-R) y proyectos FIRESEVES (AGL2017-86075-C2-1-R)Junta de Castilla y León en el marco de los proyectos FIRECYL (LE033U14) y SEFIRECYL (LE001P17)Ministerio de Educación (FPU14/00636
Molecular versus morphological markers to describe variability in sugar cane (Saccharum officinarum) for germplasm management and conservation
Sugarcane is one of the most important industrial crops in tropical and subtropical regions. INTA (Argentina) administrates a Sugarcane Germplasm Bank and carries out a breeding program. The current study was designed to assess the phenotypic and genetic diversity among 65 sugarcane accessions selected from the INTA. Clustering and ordination methods based on quantitative and qualitative morphological traits and SSR data were applied. Generalized Procrustes Analysis allowed evaluating the correlation between relationships established with both markers A good of fit between dendrograms and similarity matrices were revealed by high cophenetic coefficients (r=0.82, p<0.0001; r=0.73, p<0.0001; r=0.82, p<0.0001 for phenotypic quantitative, phenotypic qualitative and molecular data respectively). The presence of different reliable population structure was observed when considering different data sources. Procrustes allowed finding those accessions that should have been responsible for the low correlation found between the individual configurations (73%). Both morphologic and molecular markers resulted discriminative enough to differentiate among accessions. It was not possible, however, to correlate associations of markers with the origin of materials. Phenotypic and genetic distances based on morphology and molecular information serves to assist conservation and organization of collection of materials, and the choice of parent combinations for breeding purposes.
Highlights
Although both morphologic and molecular markers resulted discriminative enough to differentiate among sugarcane accessions, it was not possible to correlate associations of markers with the origin of materials.
The large number of pair-wise similarity coefficients with intermediate values determined a rather small number of nodes in clustering, which, reflects the near genetic origin of most of the materials investigated.
Diversity detected for morphological descriptors is expected since they are not usually subjected to selection inbreeding.Sugarcane is one of the most important industrial crops in tropical and subtropical regions. INTA (Argentina) administrates a Sugarcane Germplasm Bank and carries out a breeding program. The current study was designed to assess the phenotypic and genetic diversity among 65 sugarcane accessions selected from the INTA. Clustering and ordination methods based on quantitative and qualitative morphological traits and SSR data were applied. Generalized Procrustes Analysis allowed evaluating the correlation between relationships established with both markers A good of fit between dendrograms and similarity matrices were revealed by high cophenetic coefficients (r=0.82, p<0.0001; r=0.73, p<0.0001; r=0.82, p<0.0001 for phenotypic quantitative, phenotypic qualitative and molecular data respectively). The presence of different reliable population structure was observed when considering different data sources. Procrustes allowed finding those accessions that should have been responsible for the low correlation found between the individual configurations (73%). Both morphologic and molecular markers resulted discriminative enough to differentiate among accessions. It was not possible, however, to correlate associations of markers with the origin of materials. Phenotypic and genetic distances based on morphology and molecular information serves to assist conservation and organization of collection of materials, and the choice of parent combinations for breeding purposes.
Highlights
Although both morphologic and molecular markers resulted discriminative enough to differentiate among sugarcane accessions, it was not possible to correlate associations of markers with the origin of materials.
The large number of pair-wise similarity coefficients with intermediate values determined a rather small number of nodes in clustering, which, reflects the near genetic origin of most of the materials investigated.
Diversity detected for morphological descriptors is expected since they are not usually subjected to selection inbreeding
The role of prescribed fire in the provision of regulating ecosystem services of Spanish heathlands
[EN] We provide a synthesis of evidence of the effects of burning and N deposition on the provision of regulating ecosystem services of Cantabrian heathlands (NW Spain). We quantified carbon sequestration in litter, above and belowground biomass, root and soil compartments in heathlands after burning and burning plus N fertilizationS