It is becoming more and more common in the Mediterranean basin to guard against forest fires by creating wooded firebreak areas by reducing the overstory density, pruning the remaining trees and slash mulching. Nevertheless, very few attempts have been made to analyse the effect of this practice upon tree growth and the productivity of the understory plant species in semi-arid areas by following a well defined experimental design over any length of time. To remedy this lack of information, during the spring of 2005 we thinned the overstory in a semi-arid Aleppo pine (Pinus halepensis Mill.) afforestation in SE Spain (planted in the winter of 1993-1994) from an initial density of about 1,500 trees per ha according to three different thinning regimes. The annual growth data of each stand (diameter at breast height, canopy cover and basal area) were measured in randomly situated plots of 20 × 20 m and the above-ground biomass of understory plant species was also harvested from quadrats of 0.5 × 0.5 m during the early summers of 2005 to 2009. Our results showed a positive and significant response from trees in thinned stands compared to the controls, in spite of periods of low-rainfall and plague stress that unfortunately occurred during the study period. There were also statistical differences in understory biomass production within the different areas of overstory thinning as a response to the new conditions. Nevertheless, this biomass was only a small fraction of the total above-ground biomass of the afforestation, which was much higher in control plots. These tree responses and structural changes to the afforestation could be of great interest because of their implications for forest management in the context of global change in an area where increases in temperature and reductions and irregularity in precipitation, together with higher fire risks, are forecast.

En una finca localizada en el municipio de Montería, departamento de Córdoba, se evaluó el comportamiento animal en cuatro ecotipos de especies del género Brachiaria : B. brizantha CIAT 26110, B. brizantha CIAT 16322, B. brizantha cv Marandú y B. decumbens . Se utilizó semilla sexual para sembrar una hectárea de cada material, dividiéndose en dos potreros para ser manejados en sistema de pastoreo alterno de 24 días de descanso y 24 días de ocupación. En cada accesión se estimo el rendimiento de materia seca y la relación hoja/tallo a la entrada de los animales. En muestras de cada ecotipo fueron analizadas el contenido de proteína bruta, fibra en detergente neutro (FDN), fibra en detergente ácido (FDA) y la digestibilidad In Situ por 48 horas. En la época de lluvias, a los 24 días de rebrote, la producción de materia seca fue de 3534 kg/ha, 3192 kg/ha, 2684 kg/ha y 1916 kg/ha, respectivamente para B. brizantha CIAT 26110, B. decumbens , B. brizantha CIAT 16322 y B. brizantha cv Marandú, en este mismo orden, durante la época seca, a los 24 días de rebrote, los rendimientos fueron 1184 kg/ha, 950 kg/ha, 710 kg/ha y 1400kg/ha. La calidad nutritiva de los diferentes ecotipos estuvo dentro del rango de esta especies, según revisión hecha por Lascano y Euclides (1998). La ganancia de peso por animal, en una primera evaluación de 168 días (octubre a marzo), con 2 animales de carga por hectárea, fue de 1.255 kg/animal/día, 1.07 kg/animal/día, 071 kg/animal/día y 1.0 kg/animal/día, respectivamente para CIAT 16322, CIAT 26110, cv Marandú y B. decumbens . En una segunda evaluación con duración de 120 días (julio a noviembre) la ganancia de peso por animal fue de 0.51 kg/animal/día, 0.610 kg/animal/día, 0.57 kg/animal/día y 0.700 kg/animal/día, para los ecotipos CIAT 16322, CIAT 26110, cv Marandú y B. decumbens , respectivamente con una carga de 3, 5, 2 y 3 animales por hectárea.

Biogeosciences and Forestry Biogeosciences and Forestry Carbon and nutrient contents in the miscellaneous fraction of litterfall under different thinning intensities in a semiarid Pinus halepensis afforestation Carmen Segura (1) , Emilia Fernández-Ondoño (1) , M Noelia Jiménez (2) , Francisco B Navarro (3) Litterfall evaluation and the effects caused by forestry practices provide valuable information on nutrient-cycle dynamics in managed forests. So far, most of the studies have focused on leaf-fall, omitting other litterfall fractions that can be also relevant for forest and soil modelling in a global change context. With this aim the miscellaneous fraction was quantified in a Pinus halepensis afforestation in the semiarid SE of Spain five years after four different thinning regimes were applied (T75: 75% of mean basal area removed; T60: 60%; T48: 48%; and T0: no thinning). Concentrations and pools (kg ha-1) of carbon and nutrients in the miscellanea fraction were monthly analysed for C and N

Nightshades are some of the most difficult weeds to control in Upland Acala varieties of cotton. A herbicide in the newest class of acetolactase synthase inhibitors has been developed for use as a selective over-the-top broadleaf herbicide in cotton. Studies were conducted in Upland Acala cotton varieties in 1991, 1992 and 1993 to evaluate the efficacy of Staple (pyrithiobac sodium) in controlling nightshade. The herbicide was applied as early postemergence, mid-postemergence and sequential applications at rates of 0.25, 0.50, 0.75, 1.0, 2.0 and 3.0 oz of active ingredient per acre (ai/acre). Acceptable nightshade control was achieved at all rates, when applied as a single application or as sequential applications, except for the 0.25 and 0.50 oz ail acre applications. The best control was achieved when the herbicide was applied at rates of 1.0 to 3.0 oz ai/acre over the top of cotton in the cotyledon to eight trueleaf stage, with nightshade in the cotyledon to six-leaf stage. Cotton injury symptoms were evident with all treatments at 7 days after application but were nonexistent by 90 days after application. There was no evidence to indicate that pyrithiobac sodium has any longterm effect on cotton growth and development or on cotton lint yield. Because they are tolerant to dinitroaniline herbicides, nightshades (Solanum spp.) are difficult weeds to control in Upland Acala varieties of cotton (Gossypium kirsutum). Nightshades are very competitive with cotton because they germinate and grow