Efectos del muérdago (Viscum album L.) sobre el crecimiento secundario del pino silvestre (Pinus sylvestris L.) en la Sierra de Gúdar (Teruel): Interacciones con el clima

El visc és la planta hemiparàsita més estesa en els boscos de coníferes. No obstant, a penes hi ha estudis que avaluen els seus efectes sobre el creixement i el vigor dels arbres. Els peus amb major presència de visc mostren una major grandària i en el passat presentaven un creixement major que els que actualment no n'alberguen. L'increment d'àrea basimètrica es redueix a mesura que augmenta l'abundància de visc, mostrant un declivi major en l'àpex on les mates de visc estan agregades. El creixement radial dels arbres amb visc es va reduir molt després de fortes sequeres.

Comparación de la eficacia de distintos productos químicos aplicados mediante tratamiento aéreo en el control del muérdago (Viscum album) sobre Pinus halepensis

El objetivo de este trabajo fue comparar la eficacia de diversos productos químicos en el control del muérdago (Viscum album var austriacum) sobre Pinus halepensis. La experiencia consistió en la aplicación mediante tratamiento aéreo de diversas concentraciones de etefon, ácido giberélico y glifosato. Las combinaciones de ácido giberélico y glifosato obtuvieron las mayores eficacias, especialmente la que aplicó 7,8 g/ha de ácido giberélico y 540 g/ha de glifosato.

“Searching for the ghost of Tom Joad”: resurrecting Steinbeck’s gaze

This dissertation involves a close reading of Springsteen’s lyrics in relation to the thematic concerns of the Tom Joad album. Enquiring into the sometimes multiple levels of significance that these lyrics can be seen to express, in order to show the manner in which Springsteen mirrors the broader thematic concerns of Steinbeck’s The Grapes of Wrath’ s novel but also adapts and reinterprets these themes for his own time. In this sense, I will try to underline the ways in which, for Springsteen’s vision of his country in the 1990’s, the presence of troublesome issues from decades before is one that can, in certain ways, still be seen, felt and experienced. It is in this manner that the ghost of Tom Joad is summoned

Algunes plantes dels Ports de Beseit (Catalunya meridional)

Notas florísticas sobre plantas vasculares de los Ports de Beseit. Algunas son nuevas citas para esta zona: Ephedra nebrodensis, Equisetum palustre, Iberis saxatilis subsp. saxatihs; otras raras: Neotinea maculata, Ridolfia segetum, Ranunculus parviflorus. Arrbenatberum album es indicado por primera vez en Cataluña.

Discriminating crop, weeds and soil surface with a terrestrial LIDAR sensor

In this study, the evaluation of the accuracy and performance of a light detection and ranging (LIDAR) sensor for vegetation using distance and reflection measurements aiming to detect and discriminate maize plants and weeds from soil surface was done. The study continues a previous work carried out in a maize field in Spain with a LIDAR sensor using exclusively one index, the height profile. The current system uses a combination of the two mentioned indexes. The experiment was carried out in a maize field at growth stage 12–14, at 16 different locations selected to represent the widest possible density of three weeds: Echinochloa crus-galli (L.) P.Beauv., Lamium purpureum L., Galium aparine L.and Veronica persica Poir.. A terrestrial LIDAR sensor was mounted on a tripod pointing to the inter-row area, with its horizontal axis and the field of view pointing vertically downwards to the ground, scanning a vertical plane with the potential presence of vegetation. Immediately after the LIDAR data acquisition (distances and reflection measurements), actual heights of plants were estimated using an appropriate methodology. For that purpose, digital images were taken of each sampled area. Data showed a high correlation between LIDAR measured height and actual plant heights (R2 = 0.75). Binary logistic regression between weed presence/absence and the sensor readings (LIDAR height and reflection values) was used to validate the accuracy of the sensor. This permitted the discrimination of vegetation from the ground with an accuracy of up to 95%. In addition, a Canonical Discrimination Analysis (CDA) was able to discriminate mostly between soil and vegetation and, to a far lesser extent, between crop and weeds. The studied methodology arises as a good system for weed detection, which in combination with other principles, such as vision-based technologies, could improve the efficiency and accuracy of herbicide spraying.