Native Species Valuable timber plantations in Northern Guatemalan Humid Lowlands: ecological features and silvicultural feasibility

The North Humid Guatemalan Lowlands contains a significant diversity of tree species, incluiding some valuable-timber producers; these species are threatened by commercial overexploitation and habitat loss due to deforestation. The cultivation of these species in forest and agroforest plantations is a potentially viable optiontheir conservation and commercial harvesting, something that has been promoted with Government Incetemala during the past two decades. However, these species have not been widely planted, among othebecause knowledge on their ecological requirements and silviculture is scarce. A characterization of momixed plantations with 14 native valuable-timber species was made in the Humid Lowlands of Northeranalyzing for each species frequency of association and accompanying species, planted area, the main etures and growth rates. To gather information, we combined field observation and measurements with iliterature review. Based on our survey, main management challenges for cultivation of the species were described. Valuable-timber native trees could potentially be sustainably cultivated in the study zone in diffforest plantations and agroforestry schemes of coffee, cacao, cardamom and cattle; considering their suitdiversified systems, growth performance and farmer’s preferences, Swietenia macrophylla, Cedrela odordonnell-smithii, Calophyllum brasiliense and Cordia alliodora were the species with the higher potentiain plantations. However, several unsolved problems continue restricting the cultivation of these species itherefore, is essential a careful design and management

Strukturne i projektirane vrijednosti lameliranih greda i greda od cjelovitog drva Dipteryx panamensis i Hieronyma alchorneoides s brzorastućih plantaža

Dipteryx panamensis and Hieronyma alchorneoides are two species of high specific gravity used in reforestation programs in Costa Rica, but they lack products with structural value for commercialization. In order to introduce the wood of these two species in the market, the objective was established to study the behavior of solid timber beams and glued laminated timber beams of two cross sections (2 cm × 10 cm and 2 cm × 15 cm) and establish the design values in bending test. The results showed that the bending design values (fb) ranged from 2 to 26 MPa in glued laminated timber beams, while in solid timber beams, fb ranged from 6 to 15 MPa. In the shear design values (fv), the variation was from 0.29 to 0.67 MPa in glue laminated timber beams and from 1.80 to 2.58 MPa in solid timber beams. It was also found that the D. panamensis beams showed higher values than H. alchornoides beams. Finally, it was established that glued laminated timber beams showed better performance in bending parameters and higher design values, resulting in wider span values, than solid timber beams when used in floor and roof construction.Dipteryx panamensis i Hieronyma alchorneoides dvije su vrste drva velike specifične gustoće koje su uvrštene u program pošumljavanja u Kostarici, ali se ne iskorištavaju za strukturne proizvode kako bi se komercijalizirale. Da bi se te dvije vrste drva plasirale na tržište, istraženo je ponašanje lameliranih greda i greda od cjelovitog drva s dva različita poprečna presjeka (2 cm × 10 cm i 2 cm × 15 cm) te su ispitivanjem savijanja utvrđene projektirane vrijednosti. Rezultati su pokazali da su se projektirane vrijednosti savijanja (fb) kretale u rasponu od 2 do 26 MPa za lamelirane grede te od 6 do 15 MPa za grede od cjelovitog drva. Projektirane vrijednosti smicanja varirale su od 0,29 do 0,67 MPa za lamelirane grede te od 1,8 do 2,58 MPa za grede od cjelovitog drva. Za grede od drva D. panamensis izmjerene su veće vrijednosti ispitivanih svojstava nego za grede od drva H. alchorneoides. Konačno, utvrđeno je da su lamelirane grede pokazale bolja svojstva savijanja i veće projektirane vrijednosti od greda od cjelovitog drva, što rezultira većim vrijednostima raspona kada se rabe na podu ili krovu

Do multipurpose companion trees affect high value timber trees in a silvopastoral plantation system?

Establishment of native timber trees on deforested land may contribute to the livelihood of farmers, to improved ecosystem services and to increased greenhouse gas uptake. Here, we present a new silvopastoral planting design to assess species performance and interspecific competition or facilitation effects among native timber and multipurpose trees in Central America. Two timber species, Tabebuia rosea and Cedrela odorata, were established in three low-density planting regimes allowing combined tree and future livestock production: (1) solitary planting, (2) companion planting with Guazuma ulmifolia, and (3) companion planting with the nitrogen-fixing Gliricidia sepium. We quantified survival, growth and reforestation potential of the two timber species subjected to the different planting regimes for the first 2years after establishment. Nitrogen concentration as well as stable nitrogen and carbon isotope composition (δ15N, δ13C) of leaves of the timber saplings were determined. T. rosea showed higher survival and better growth than C. odorata under varying environmental conditions (soil, concomitant vegetation). Performance of the timber saplings was unaffected by either companion species. Planting regimes had no effect on foliar nitrogen concentration and δ15N of the two timber species, although δ15N values indicated nitrogen fixation activity in G. sepium trees. Planting regimes affected foliar δ13C values in T. rosea. δ13C values were significantly higher in solitarily growing individuals, suggesting lower exposition to water stress conditions in saplings surrounded by companion species. As we found positively correlated growth traits among timber and multipurpose trees, a combined planting may benefit farmers by providing additional goods and service

The Effect of Corrective Feedback on Performance in Basic Cognitive Tasks: An Analysis of RT Components

[EN] The current work examines the effect of trial-by-trial feedback about correct and error responding on performance in two basic cognitive tasks: a classic Stroop task (n = 40) and a color-word matching task (n = 30). Standard measures of both RT and accuracy were examined in addition to measures obtained from fitting the ex-Gaussian distributional model to the correct RTs. For both tasks, RTs were faster in blocks of trials with feedback than in blocks without feedback, but this difference was not significant. On the other hand, with respect to the distributional analyses, providing feedback served to significantly reduce the size of the tails of the RT distributions. Such results suggest that, for conditions in which accuracy is fairly high, the effect of corrective feedback might either be to reduce the tendency to double-check before responding or to decrease the amount of attentional lapsing.Moret-Tatay, C.; Leth-Steensen, C.; Quarty-Irigaray, T.; Iracema De Lima-Argimon, I.; Gamermann ., D.; Abad Tortosa, D.; Oliveira, C.... (2016). The Effect of Corrective Feedback on Performance in Basic Cognitive Tasks: An Analysis of RT Components. Psychologica Belgica. 56(4):370-381. doi:10.5334/pb.240S37038156

Agroforestry systems of timber species and cacao: survival and growth during the early stages

In recent times, increased emphasis has been placed on diversifying the types of trees to shade cacao (Theobromacacao L.) and to achieve additional services. Agroforestry systems that include profitable and native timber trees are a viable alternative but it is necessary to understand the growth characteristics of these species under different environmental conditions. Thus, timber tree species selection should be based on plant responses to biotic and abiotic factors. The aims of this study were (1) to evaluate growth rates and leaf area indices of the four commercial timber species: Cordia thaisiana, Cedrela odorata, Swietenia macrophylla and Tabebuia rosea in conjunction with incidence of insect attacks and (2) to compare growth rates of four Venezuelan Criollo cacao cultivars planted under the shade of these four timber species during the first 36 months after establishment. Parameters monitored in timber trees were: survival rates, growth rates expressed as height and diameter at breast height and leaf area index. In the four Cacao cultivars: height and basal diameter. C. thaisiana and C. odorata had the fastest growth and the highest survival rates. Growth rates of timber trees will depend on their susceptibility to insect attacks as well as to total leaf area. All cacao cultivars showed higher growth rates under the shade of C. odorata. Growth rates of timber trees and cacao cultivars suggest that combinations of cacao and timber trees are a feasible agroforestry strategy in Venezuela

SISTEMA AGROFORESTAL DE YUCA Y GUANANDI (Calophyllum braziliense) EN EL VALLE DE PARAÍBA, ESTADO DE SÃO PAULO, BRASIL

La eliminación de vegetación ribereña y un uso intenso de terrazas en el Valle del Río Paraíba do Sul, Estado de São Paulo, Brasil, han causado la degradación de la tierra y la lixiviación de nutrientes y sedimentos por la lluvia. En el año 2008, se introdujo el guanandi – Calophyllum braziliense (3x2m); árbol nativo resistente a inundaciones y productor de madera fina; después del corte de eucaliptos en las terrazas. En 2011 ha comenzado a conversión de agroforestería con un experimento en bloques al azar con 8 repeticiones de cada tratamiento: guanandi, guanandi + yuca (Manihot esculenta) y yuca en sistema agroforestal + guanandi (SAF). La yuca fue plantado entre las líneas de guanandi en filas dobles (0,8 x 0,8 m) y yucas en SAFs fue introducida: Musa sp. BRS Conquista entremezclado con palma juçara (Euterpe edulis), Cajanus cajan y árboles nativos: Croton urucurana, Schinnus terenbinthifolius, Zanthoxilylum rhoifolium, Inga sp., Pseudobombax grandiflorum, Erytrina sp. y Johannesia princeps entre las líneas de yuca. El objetivo de los árboles y arbustos fue reciclar nutrientes, aumentar las reservas de carbono del suelo y restaurar el bosque ribereño con la diversidad biológica. La variedad de yuca biofortificada (IAC06-01) se obtuvo por crianza clásica, contiene 1.400 UI de vitamina A. El rendimiento promedio de raíces en consorcio con guanandi fue 6.099 kg/ha y el SAF 4.940 kg/ha para una población de 5.555 plantas/ha, lo que significa un promedio de 1,10 y 0,89 kg raíces comerciales por planta. Sin embargo, en el SAF será la producción de plátanos, quinchoncho frijoles y frutas de juçara. Los SAFs pueden convertirse en una de las mejores opciones para diversificar los ingresos, alineando la producción de madera fina, leña y alimentos, reduciendo la cantidad de fertilizantes sintéticos que generan ingresos adicionales a los productores con la conservación del medio ambient

A Theory of Reaction Time Distributions

We develop a general theory of reaction time (RT) distributions in psychological experiments, deriving from the distribution of the quotient of two normal random variables, that of the task difficulty (top-down information), and that of the external evidence that becomes available to solve it (bottom-up information). The theory provides a unied account of known changes in the shape of the distributions depending on properties of the task and of the participants, and it predicts additional changes that should be observed. A number of known properties of RT distributions are homogeneously accounted\ud for by variations in the value of two easily interpretable parameters: the coefficients of variation of the two normal variables. The predictions of the theory are compared with those of multiple families of distributions that have been proposed to account for RTs, indicating our theory provides a significantly better account of experimental data. For this purpose, we provide comparisons with four large datasets across tasks and modalitities. Finally,\ud we show how the theory links to neurobiological models of response latencies

Presence of ascogregarina culicis and ascogregarina sp. In natural sympatric populations of aedes aegypti and ae. albopictus (diptera: Culicidae) in argentina

Aedes aegypti is the main vector of the four arboviruses in America which have the greatest impact on human health. The introduction of Aedes albopictus in South America and Argentina acquires importance given the possibility that this species may be a new vector of arboviruses in this region. For this reason, the studies of the biology of their parasites, such as Ascogregarina spp., should be important for the knowledge of the invasive behavior of these vectors. We reported the finding of Ascogregarina culicis in Aedes aegypti and Ascogregarina sp. in Ae. albopictus populations in subtropical Argentina. The prevalence of parasitism by A. culicis in Ae. aegypti and Ascogregrarina sp. in Ae. albopictus was 34.81% (n = 464) and 37.23% (n = 70), respectively, differing between the seasons and habitats. The infection intensity caused by A. culicis and Ascogregarina sp. varied between 1 to 250 and 1 to 327 trophozoites respectively. Ascogregarina culicis was found throughout the all sampling period of Ae. aegypti (June 2016-April 2018). However the presence of Ascogregarina sp. in the midgut of Ae. albopictus was not recorded throughout the whole sampling period despite the presence of the host.Fil: Alonso, Ana Carolina. Universidad Nacional del Nordeste. Instituto de Medicina Regional. Área de Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Stein, Marina. Universidad Nacional del Nordeste. Instituto de Medicina Regional. Área de Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Micieli, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentin