Sergio Espinoza

Influence of cambial age and climate on ring width and wood density in Pinus radiata families

Abstract• ContextThe correlation between tree ring width and density and short-term climate fluctuations may be a useful tool for predicting response of wood formation process to long-term climate change.• AimsThis study examined these correlations for different radiata pine genotypes and aimed at detecting potential genotype by climate interactions.• MethodsFour data sets comprising ring width and density of half- and full-sib radiata pine families were used. Correlations with climate variables were examined, after the extraction of the effect of cambial age.• ResultsCambial age explained the highest proportion of the ring to ring variation in all variables. Calendar year and year by family interaction explained a smaller but significant proportion of the variation. Rainfall had a positive correlation with ring width and, depending on test site, either a negative or positive correlation with ring density. Correlations between temperature during growing season and ring density were generally negative.• ConclusionClimate variables that influence ring width and wood density can be identified from ring profiles, after removing the cambial age effect. Families can be selected that consistently show desirable response to climate features expected to become prevalent as a result of climate change.

Effect of shading and fertilisation on the development of container-grown Nothofagus glauca seedlings, a threatened species from central Chile

Nothofagus glauca is an endemic tree of the Mediterranean zone of Chile and is a threatened species. Currently, available information for the propagation and nursery cultivation of this species is conspicuously lacking. This study examined the effect of four levels of shade (18%, 35%, 65% and 80% with Raschel® plastic net) and four rates of slow-release fertiliser (2.5, 5, 7.5, and 10 g l−1 of Basacote® Plus 9M) on container-grown seedlings after one growing season. Growth was significantly affected by shade and fertilisation. Seedlings grown under 18% or 35% shade were larger in diameter and had more roots than those grown under 80% shade and fertilisation with 2.5–5 g l−1 of media were smaller than those fertilised with 7.5–10 g l−1.

Efectos combinados de la restricción hídrica, el tamaño de contenedor y la dosis de fertilizante en la supervivencia, intercambio gaseoso y atributos morfológicos en plantas de Quillaja saponaria

Quillaja saponaria is a valuable commercial and ecological Chilean native species that has suffered considerably degradation countrywide; however, the determination of the optimum characteristics of the planting stock, an important aspect in restoration projects, has receive little attention. The aim of this study was to evaluate the effect of container size and dose of fertilizer on morphological and physiological responses of Q. saponaria seedlings cultivated in a nursery under well-watered and water restricted conditions. After 27 days growing under contrasting watering regimes, growth, biomass allocation, and gas exchange were measured in 6-month-old seedlings. We found that survival, height and diameter increment, and root dry weight were higher in the water stressed seedlings cultivated in large containers. The water stressed seedlings cultivated in large containers also had superior stomatal conductance, however when the fertilizer dose was decreased, this trait decreased considerably. Thus, a superior performance in a water-restricted environment could be expected in those seedlings cultivated in larger containers with low fertilizer.

Biomass production and carbon balance of a short rotation forestry of Populus deltoides (clone Lux) under two different cutting cycles

The emissions of green house gases contribute to global warming. Consequently, renewable energies such as solar, wind power, hydropower and bio energy appear as alternatives for reducing these emissions. One promising source of renewable energy is forest biomass, for it is considered to have neutral CO2 balance. The problem is to quantify the amount of CO2 that is emitted for a certain amount of energy generated, compared to the CO2 emitted to generate the same amount of energy from a non-renewable source. In this paper we calculate biomass production and carbon dioxide balance of an eight-year-old Populus deltoides short rotation forestry (SRF) under two cutting cycles (harvesting every two years, biennial and every three years, triennial). We also compare the amount of energy generated per kg of CO2 emitted in the use of fossil fuels versus the amount of energy generated per kilogram of CO2 emitted. On the one hand, total biomass yield was 12.6 ± 0.9 Mg ha-1 year-1 and 15.1 ± 1.5 Mg ha-1 year-1 for biennial and triennial cutting cycles respectively. On the other hand, total emissions of CO2 for growing a poplar SRF with a cycle of eight year and biennial cutting sequence reached a value of 738.8 kg ha-1 year-1; however, triennial short total emissions are equivalent to 695.5 kg ha-1 year-1. We concluded that the use of biomass makes a positive contribution to the reduction of greenhouse gases, in particular CO2, reducing emissions almost five times compared with fossil fuels.

Energy balance in a bioenergy plantation of Populus deltoides clone Lux in a site with Mediterranean environment.

Ante el desafio energetico al cual se enfrenta el mundo en general, y Chile no es una excepcion, los cultivos forestales con destinacion energetica se han ido posicionando como una alternativa viable para la diversificacion de la matriz energetica del pais. Este tipo de cultivos, aun en fase de desarrollo, se basan en turnos cortos de rotacion con altas producciones de biomasa. El problema surge a la hora de evaluar la sostenibilidad de dichos cultivos. El calculo del balance energetico es clave para valorar dicha sostenibilidad, es decir, no se puede gastar mas energia en producir biomasa que la que esta otorga con la combustion. En este trabajo se calcula el balance energetico, considerando los productos de la cosecha puestos a orilla de camino, de un cultivo de Populus deltoides clon Lux con fines energeticos durante un periodo de ocho anos (2000-2008), comparando un turno de rotacion bienal (T2) con uno trienal (T3) en un sitio con ambiente mediterraneo. Para ello se ha calculado el costo energetico de la produccion y cosecha, y la cantidad de energia liberada en la combustion de la biomasa generada. En ambos turnos de rotacion se obtienen resultados positivos, siendo mas conveniente energeticamente el turno trienal respecto al bienal (34,7 T2 vs 25 T3).