Modeling canopy structure effects on loblolly pine growth

This study examined several aspects of canopy structure and their influence on growth of loblolly pine (Pinus taeda L.) plantations. Foliage distribution, crown hydraulic architecture, and the effect of chronological changes in canopy structure on stand development were explored as possible components of a future process-based model intended for management purposes. A model based on the Johnson’s SB distribution was developed to predict leaf area distribution of loblolly pine trees. This is a preliminary step for building a submodel capable of simulating chronological changes in canopy structure and stand growth. The model accurately predicted the cumulative distribution of leaf area in the crown. It has the potential to be included in forest growth models where an accurate description of leaf area distribution is needed. A novel process-related, non-carbon-based growth model for predicting the growth of closed, unthinned, loblolly pine stands was developed. Its ability to represent the dynamics of the canopy and stand growth was evaluated. Overall, model predictions were in agreement with reported observations or proposed theories in relation to stand growth, size-density relations, and relationships between canopy dynamics and stand growth. Modeling the hydraulic architecture of the crown is important because it controls crown recession. Patterns in branch permeability with crown depth and permeability at the top of the main stem were analyzed for loblolly pine trees from families selected for differences in growth rate and crown size. The results showed that branch permeability decreased significantly from the top to the bottom of the crown and that genetic-based differences might exist in patterns of stem and branch permeability. The study showed the potential of using a process approach to develop a forest growth model and utilizing mechanistic and empirical elements in the construction of the simulator. In addition, the integration and synthesis of information coming from diverse sources in the model allow the possibility of detecting deficiencies in the understanding of key processes and provide a guide for formulating hypotheses and planning experiments to fill the gaps in knowledge of the processes regulating stand development

Minería colombiana: porque la minería hace parte de las locomotoras del gobierno de Colombia

El presente trabajo pretende determinar la importancia del sector minero en el crecimiento económico del país, teniendo en cuenta que ha sido planteado como uno de los ejes primarios del Gobierno actual

Determinación de ganancia de peso y estatura en ovinos de diferentes edades en el ceypsa

This research work was carried out in the Cotopaxi province, Eloy Alfaro Parish, Salache neighborhood, in the Technical University of Cotopaxi at “Agricultural science and Natural resources Academic Unit”. In this research 39 ovine of different races such as dorper, merino, katadin, frisiona where used because the project of the institution already had them. The relevant research collected data and genetic improvement of ovine. Then, the measurement of weight gain and height of ovine was made through the use of weight balance and measuring tape for height, this activity was made each seven days during a determined time. Once, collected the weekly weight of each one of the animals we proceeded to calculate through formulas to get the results and realize if the weight gain exists and finally the determination of the ovine age. After analyzing the weight results of each one animal it was detected that not all animals gain weight or height just a few animals could do it.El proyecto de investigación se realizó en la provincia de Cotopaxi Parroquia Eloy Alfaro barrió Salache, en la Universidad Técnica de Cotopaxi “Unidad Académica de Ciencias Agropecuarias y Recursos Naturales”. Lo relevante de la investigación fue la Recopilación de datos y mejoramiento genético de los ovinos del Ceypsa Se trabajó con 39 ovinos de las siguientes razas Dorper, merino, Katadin, Frisona que posee el proyecto de dicha institución de igual manera Se determinó la edad de los ovinos mediante la revisión de los registros existentes también se agruparon a los animales según sus características fenotípicas se realizó la medición de la ganancia de peso y estatura en los ovinos la cual lo realizamos mediante la utilización de una balanza para la ganancia de peso y una cinta métrica para la estura, esta actividad se lo realizaba cada siete días durante un tiempo determinado, una vez recolectado los pesos semanales de cada uno de los animales procedimos a los cálculos mediante fórmulas para obtener los resultados y darnos cuenta si existió ganancia de peso y estatura y finalmente la determinación de la edad de los ovinos

Mixed Forest Plantations with Native Species for Ecological Restoration in Cloud Forests of the Venezuelan Andes

Tropical cloud forests play a fundamental role in the hydrological cycle of mountain watersheds having the largest biodiversity per unit area. In Venezuela, cloud forests are subject to intense deforestation and fragmentation by farming and cattle-ranching causing soil erosion, water cycle alteration, and biodiversity loss. Reforestation projects used exotic species as Pines and Eucalyptus, native species were rarely planted by lacking knowledge on species requirements and management. We report the performance of 25 native cloud forest species differing in shade-tolerance, planted in mixed assemblies on degraded areas. Tree survival and the individual tree variables: total height, root-collar diameter, tree-slenderness, and crown-ratio were evaluated at 1, 2, 4.5 and 7 years-old. Data was analyzed with a repeated measures analysis of variance mixed model considering species shade-tolerance, light intensity at planting and age as explanatory factors. Survival was over 80%. Shade-intolerant species displayed faster height and root-collar diameter growth. Shade-tolerant species had larger crown ratios due to persistence of lower branches; whereas, shade-intolerant showed signs of crown recession at age 7. Slenderness values from age 4.5 were indicative of good trees stability and health across treatments. The positive results have motivated landowners to establish native species plantations in critical areas with our support

Repotenciación vial y traslado de equipo extrapesado entre Carepa y Heliconia (Antioquia)

Las fuentes de energía son determinantes para el desarrollo de un país, esta necesidad impulsa a los diferentes organismos estatales a garantizar la disponibilidad del servicio de energía para la industria, el comercio y el área residencial. El sistema eléctrico se compone de varios elementos, destacando entre ellos las generadoras de energía, redes y los transformadores de potencia. La creación de nuevas fuentes de energía conllevara a la necesidad de construcción de líneas y unidades de transformación que adecuen los parámetros a valores aptos para hacer la actividad de transmisión viable. La tarea de garantizar la disponibilidad de elementos se hace compleja por las dimensiones y características de las unidades transformadoras, con gran tamaño y peso excesivo, dificultando el traslado de forma tradicional en las vías disponibles, sumado a esto, la construcción de generadoras y subestaciones eléctricas en sectores con vías terciaras, complican el panorama para la ubicación de las unidades en los lugares requeridos. La central Hidroeléctrica Ituango es uno de los ejemplos de la problemática expuesta. este proyecto transmitirá energía en una red ya construida, requiriendo de transformadores de potencia para integrarse al sistema interconectado nacional. Sin embargo, la ubicación de la subestación y la línea se encuentra en territorios con acceso por vías terciarias que no cuentan con las características para el transporte de carga extrapesada. En este contexto surge la necesidad de adecuar los corredores viales que garanticen las condiciones de seguridad en el traslado de la carga y permitan la conexión de Hidroituango al sistema energético.The energy sources are decisive for the development of a country, this need drives the different state organisms to guarantee the availability of the energy service for the industry, the commerce and the residential area. The electrical system is composed of several elements, highlighting among them the energy generators, networks and power transformers. The creation of new energy sources will lead to the need to build lines and transformation units that adapt the parameters to suitable values in order to make the transmission activity viable. The task of guaranteeing the availability of elements is complex because of the dimensions and characteristics of the transformer units, with large size and excessive weight, making it difficult to move in a traditional way on the available roads. In addition to this, the construction of generators and electrical substations, in sectors with tertiary roads, complicates the situation for the location of the units in the required places. The Ituango Hydroelectric Power Plant is one of the examples of the problem exposed, this project will transmit energy in an already built network, requiring power transformers to be integrated into the national interconnected system. However, the location of the substation and the line are in territories with access by tertiary roads that do not have the characteristics for the transport of extra heavy cargo. In this context, there is a need to adapt the road corridors that guarantee safety conditions in the transfer of cargo, and allow the connection of Hidroituango to the energy system

Implementación de servicios de infraestructura IT en zentyal server 5.0

En este artículo se busca abordar la importancia de Zentyal Server como plataforma para la administración de la Infraestructura IT dentro de una organización que quiera estar a la vanguardia tecnológica, donde se explicará de manera técnica la implementación de esta importante herramienta.This article seeks approach the importance of Zentyal Server as a platform for the administration of the IT Infrastructure within an organization that wants to be stay ahead in technology, where the implementation of this important tool will be explained in a technical manner

Diagnóstico de gestación en bovinos

Escrito en el que se compila información proveniente de la literatura existente, además de las experiencias de profesionales de campo y profesores del área reproductiva para el aprendizaje y/o mejoramiento de los conceptos básicos para la detección de preñez en bovinos.Written in which information from existing literature is compiled, in addition to the experiences of field professionals and teachers in the reproductive area for learning and / or improving the basic concepts for the detection of pregnancy in cattle.Diagnóstico de gestación por palpación rectal -- Palpación rectal -- Fluctuación uterina -- Asimetría de los cuernos -- Examen de los ovarios -- Folículos -- Ecografía reproductiva -- Principios básicos -- Defectos de imagen -- Examen ultrasonográfico del tracto reproductivo de la hembra bovina -- Morfología ultrasonográfica del ovario -- Utrasonografía durante el proceso de ovulación -- Morfología ultrasonográfica del cuerpo lúteo (cl) -- Ultrasonografía de patologías ováricas -- Morfología ultrasonográfica del útero vacío -- Determinación de la gestación por ultrasonografía -- Determinación del sexo -- Otras aplicaciones de la ultrasonografía en la reproducción animalna83 página

Occupational exposure of workers to pesticides: Toxicogenetics and susceptibility gene polymorphisms

Farm workers are often exposed to pesticides, which are products belonging to a specific chemical group that affects the health of agricultural workers and is mostly recognized as genotoxic and carcinogenic. The exposure of workers from Piauí, Brazil, to these hazardous chemicals was assessed and cytogenetic alterations were evaluated using the buccal micronucleus assay, hematological and lipid parameters, butyrylcholinesterase (BChE) activity and genetic polymorphisms of enzymes involved in the metabolism of pesticides, such as PON1, as well as of the DNA repair system (OGG1, XRCC1 and XRCC4). Two groups of farm workers exposed to different types of pesticides were evaluated and compared to matched non-exposed control groups. A significant increase was observed in the frequencies of micronuclei, kariorrhexis, karyolysis and binucleated cells in the exposed groups (n = 100) compared to controls (n = 100). No differences were detected regarding the hematological parameters, lipid profile and BChE activity. No significant difference was observed either regarding DNA damage or nuclear fragmentation when specific metabolizing and DNA repair genotypes were investigated in the exposed groups

Optimizing thinnings for timber production and carbon sequestration in planted teak (Tectona grandis L.f.) stands

Aim of study: We developed an optimization model for determining thinning schedules in planted teak (Tectona grandis L.f.) stands that maximize the financial output in terms of soil expectation value (SEV) and net present value (NPV) considering a) the simultaneous optimization of timber production and carbon (C) sequestration and b) only for C sequestration.Area of study: Planted teak forests in the western alluvial plains of Venezuela.Material and methods: We integrated a stand growth and yield model with a constrained optimization model based on genetic algorithms (GA) for determining optimal thinning schedules (number, age, and removal intensity) that maximize SEV when simultaneously managing for timber production and C sequestration. The data came from permanent plots established in planted teak stands with remeasurements from 2 to 32 yr.-old. Plots differ in site quality, initial spacing, and thinning schedules. We obtained optimal thinning schedules for several scenarios combining site quality, initial spacing, interest rates, harvest and transport costs, as well as timber and C prices. The stand growth and yield model estimates timber products and C flows (storage and emissions) until most stored C is reemitted to the atmosphere.Main results: When considering simultaneously both, timber production and C sequestration, the scenario with the maximum SEV consisted of initial stand densities = 1,111 trees ha-1, site quality (SQ) I, harvest age 20 years, and four thinnings (ages 6, 10, 14, 17 with removal intensities 26 %, 28 %, 39 %, and 25 % of stand basal area respectively). For maximizing C sequestration only, the best schedule consisted of 1,600 trees ha-1, SQ I, harvest age 25 years, with no-thinning. A sensitivity analysis showed that optimal schedules and SEV were highly sensitive to changes in interest rates, growth rates, and timber prices.Research highlights:The management schedules favoring merchantable timber production are not the same that favor C sequestration.For planted teak, the objectives of maximizing timber production and carbon sequestration are in conflict because the thinning schedules that maximize financial gains from C sequestration reduce economic gains from timber and vice versa.With actual timber teak and market C prices, optimal NPVW is much larger than optimal NPVC.For C prices under 40 $US MgC optimizing simultaneously for timber production and C sequestration is the best option, as additional although sub-optimal revenues can be obtained from C payments.Lengthening the rotation, avoiding thinnings, or reducing their intensity increase carbon storage in planted teak, although, under the analyzed scenarios, after 120 yr. almost all carbon has been re-emitted to the atmosphere.Additional keywords: heuristics, genetic algorithms, operations research, forest management planning, stand level model, carbon stocks.Abbreviations used: C (Carbon); GA (genetic algorithm); NPVW, NPVC, NPVT (net present value from the cash flows of timber (wood), carbon, and total); SEV (Soil (land) expectation value); dbh (diameter at 1.3 m from the ground); G (stand basal area); Gp (potential site carrying capacity in terms of G); SQ (site quality); R (rotation, harvest age); A (age); I (thinning intensity); Vob, Vub (overbark, underbark volume); gr (basal area growth rate); r (interest rate); harvest and transport costs (Hc); Pc (C price).