Biogeochemistry of Dominant Plants and Soils in Shewushan Gold Lateritic Deposit, China

This paper describes the effect of mineral elements on dominant plants in the Shewushan lateritic gold deposit, China. For this purpose, 30 soil profile samples at different depths and 3 kinds of dominant plants including Populus canadensis (Populus X canadensis Moench), Cinnamomun camphora (Cinnamomum camphora (L.) Presl.) and Rhus chinensis (Rhus chinensis Mill.) were collected. The concentration of ore-forming elements including Au, Ag, Pb, Zn, Cu, As, Fe, and S were analyzed. Based on the investigation of two mine profiles, it can be found that Au, Pb, As, and Fe were mainly enriched in laterite layer and the brown clay layer at a depth of 5–11 m. Moreover, the biological accumulate coefficient (BAC) and the contrast coefficient (CM) were calculated to assess the sensitivity and concentrating ability of Populus canadensis and Cinnamomun camphora. To investigate the response of the two species to metal stress, the contents of chlorophyll, malondialdehyde (MDA), and activities of superoxide dismutase (SOD) and peroxidase (POD) were determined. The result showed that Populus canadensis and Cinnamomun camphora have a high tolerance to metal stress and that both of the two species can indicate the content of Au, As, Pb, and Co in topsoil.

Growth and foliar nutrition of a hybrid poplar clone following the application of a mixture of papermill biosolids and lime mud

Fertilization of hybrid poplar (HP) plantations with papermill by-products is a promising solution to improve soil fertility and nutrient availability, increase plantation productivity, and provide added value to these materials that would otherwise be incinerated or sent to the landfill. We assessed the growth and foliar nutrition of a HP clone (Populus x. canadensis × P. maximowiczii) at six plantation sites aged three to five years in southern Quebec, Canada. Sites received a fertilization treatment consisting of a mixture of papermill biosolids (120 to 140 t ha-1, depending on site) and lime mud (10 to 15 t ha-1) before being planted, or no fertilization (control). Tree growth was significantly improved by fertilization, with fertilized trees showing a mean annual height increment of 1.3 m (all-site mean; SD = 0.2), compared with 0.5 m (SD = 0.4) for unfertilized trees. Foliar Ca and Mg increased following fertilization and levels met optimal thresholds at all sites, whereas N, P, and K concentrations also increased but nutritional deficiencies remained for these elements at several sites. Our results confirm the benefits of fertilizing hybrid poplars with papermill by-products, but indicate that adjustments in application rates or type of by-products could be made in order to fully satisfy nutritional requirements and thus optimize tree growth.

Adaptability of Tree Species as Windbreaks for Urban Farms in the U.S. Intermountain West

Windbreaks or shelterbelts are a management tool to protect crops from damaging horizontal wind flow, and may provide a useful buffer between farmland and urbanized areas by reducing pesticide drift, dust, and noise associated with farming activities. Plant selection for windbreaks in the Intermountain West can be difficult as high elevation coupled with extreme temperatures, high pH soils, and limited access to water are common. This study assessed eight tree species for suitability as a windbreak in the Intermountain West, with a particular focus on initial establishment and use at the urban–agriculture interface. Species were assessed for mortality, size, canopy density, insect and disease issues, and initial cost. Measurements of shadow characteristics were used as a novel approach to compare canopy density and porosity. Standard poplar (Populus x canadensis) and ‘Theves’ columnar poplar (Populus nigra ‘Afghanica’) were the most effective at rapid establishment, but species with more moderate growth rates, such as aspen, juniper, and hackberry, may provide lower long-term maintenance costs for the environmental conditions found in the Intermountain West.

CHEMICAL ALTERATIONS OF HARDWOOD VENEERS DUE TO THERMAL TREATMENT

Wood is the most popular building material in the world due to its universal versatility, although it has disadvantages - the difficulty to apply small diameter logs in construction, hygroscopicity and anisotropic swelling and shrinking. To solve these disadvantages, plywood from wood material is produced. Plywood is a material that can solve anisotropy, but it is still biodegradable by rot and stain fungi. Thermal treatment is a methodology that improves the durability of wood. In this paper aspen (Populus tremula L.), poplar (Populus x canadensis Moench) and birch (Betula pendula Roth) were treated by steam (WTT) and vacuum (TERMOVUOTO) devices under 160°C/50 min (birch and aspen), 204°C/2 h, 214°C/2 h, 217°C/3 h, 218°C/30 min (birch and poplar). Chemical changes in treated veneers were investigated by ATR-FTIR (Attenuated Total Reflection Fourier Transform Infrared Spectroscopy) in a range 2000 cm-1 – 800 cm-1. ATR-FTIR is a non-destructive methodology, which is important during manufacturing process quality control. Untreated poplar wood and aspen wood had similar ATR-FTIR spectra because both species belong to Populus genus. Untreated birch wood had higher absorption intensity peak at 1740 cm-1, which indicates the C=O bond stretching in the carboxyl group depicting more acetyl groups in birch wood than in aspen/poplar. According to spectral data, birch wood, treated in TERMOVUOTO process at 200°C for 2 hours is chemically almost identical to untreated one. WTT process causes the most significant changes in the chemistry of both in aspen and birch. Therefore, regime 160°C/50 min in water vapour is more aggressive than treatments at higher temperatures and under reduced pressure. It is expected that plywood produced from WTT treated veneers will have reduced strength in comparison with TERMOVUOTO process produced ones.

Sistemas agroforestales con chopo, una oportunidad

Los sistemas agroforestales silvoarables han estado presentes en la agricultura tradicional durante milenios. Sin embargo, la industrialización de la agricultura y posteriormente la Política Agraria Común los ha marginado durante décadas. En las últimas reformas de la PAC ha habido un cambio de tendencia gracias a creciente consideración de los objetivos medioambientales de la Unión Europea. Por ejemplo, la nueva PAC contempla la presencia de hasta 100 pies de arbolado por hectárea para el cobro de ayudas directas e incluye en el Pilar II las ayudas para el establecimiento de sistemas agroforestales, si bien la aplicación de ambas medidas depende de los países miembros.El chopo híbrido (Populus x canadensis) es ampliamente reconocido como uno de los mejores árboles para el establecimiento de sistemas agroforestales en zonas templadas gracias a su rápido crecimiento, cortos turnos de aprovechamiento y la existencia de demanda industrial su madera para la industria del contrachapado. En concreto la industria española del contrachapado de chopo es un referente a nivel europeo y mundial por la calidad de sus productos y su marcado carácter exportador.Para la implementación de las ayudas europeas al desarrollo rural referentes al establecimiento de sistemas agroforestales se requiere de una demanda de las mismas por parte de los agricultores. Para que esto sea posible resulta fundamental el desarrollo de experiencias, en este caso con diferentes cultivos, clones de chopo y espaciamientos, obteniendo datos científicos sobre producción, rentabilidad y beneficios ambientales que fomenten un desarrollo futuro de estos sistemas de cultivo.

Determinación de la epoca de poda en sistemas silvopastoriles con alamos en Patagonia Norte Argentina

Según experiencias de los productores presentes en los valles irrigados de Patagonia norte, la época en que se realiza la poda en álamos influye en la cantidad de rebrotes que el árbol genera en la siguiente etapa de crecimiento. La aparición de brotes epicórmicos afecta tanto la calidad de la madera como la rentabilidad de la producción, razón por la que es de importancia determinar el momento más adecuado para realizar esta tarea. Con este objetivo se instalaron dos ensayos, en el año 2012, en dos establecimientos ubicados en esta zona, y para dos clones diferentes de álamo, Populus x canadensis 'I 214' y Populus x canadensis 'Conti 12'. Estos ensayos consistieron en 39 árboles podados en tres épocas de poda (otoño, primavera y verano). Los árboles fueron seleccionados al azar y se les aplicó una poda sistemática hasta el 50% de su altura y una poda de formación