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Some alien tree species used in commercial forestry and agroforestry cause major problems as invaders of natural and seminatural ecosystems. The magnitude of the problem has increased significantly over the past few decades, with a rapid increase in afforestation and changes in land use. Trends can be explained by analyzing natural experiments created by the widespread planting of a small number of species in different parts of the world. The species that cause the greatest problems are generally those that have been planted most widely and for the longest time. The most affected areas have the longest histories of intensive planting. Pinus spp. are especially problematic, and at least 19 species are invasive over large areas in the southern hemisphere, where some species cause major problems. The most invasive Pinus species have a predictable set of life-history attributes, including low seed mass, short juvenile period, and short interval between large seed crops. Pine invasions have severely impacted large areas of grassland and scrub-brushland in the southern hemisphere by causing shifts in life-form dominance, reduced structural diversity, increased biomass, disruption of prevailing vegetation dynamics, and changing nutrient cycling patterns. The (unavoidable) negative impacts of forestry with alien species are thus spilling over into areas set aside for conservation or water production. There is an urgent need to integrate the various means available for reducing the negative impacts of current invaders and to implement protocols to regulate the translocation of species that are known to be invasive.

Se analizó de forma perceptual la transferencia de conocimiento en tecnología de la madera en instituciones educativas estatales de Costa Rica. Se realizaron capacitaciones activo-pasivas en temas de secado, preservado y calidad de la madera, llevando a cabo tres evaluaciones de aprendizaje (precurso, postcurso y 30 semanas luego del postcurso). Con estas se valuó la percepción, conocimiento adquirido y limitaciones de los sistemas empleados. Se obtuvo una gran similitud entre las temáticas de secado y preservado con conocimientos previos superiores al 65 %, aprendizajes del 85 % y retenciones de conocimiento del 75 %; caso contrario se evidenció con la temática de calidad, la cual presentó un conocimiento previo del 20 %, aprendizaje del 83.5 % y retención del 75.6 %; los temas de secado y preservado mostraron la mejor percepción, considerados como simples, aplicables, útiles y entendibles; mientras que el tema de calidad se consideró complicado, complejo, inaplicable pero útil. Finalmente, se encontró que el aprendizaje de secado y preservado debe ser una combinación de 50 %-50 % entre teoría-práctica; mientras la calidad debería ser 25 %-75 % teoría-práctica.

The insecticide effect of new and mature leaf extracts obtained with ethanol and water from Schinus molle L. (Anacardiaceae) were evaluated at 0.5 - 3.4% w/v, and 0.5 - 4.8% w/v, respectively, onto larvae of Gonipterus platensis Marelli (Coleoptera: Curculionidae), an important defoliating pest on eucalypt (Eucalyptus spp., Myrtaceae) plantations. The extracts were applied to eucalypt leaves that were given as food to the larvae, and their effects were determined by determining mortality and the LC50 and LT50 by Probit analysis on the larvae. Both extracts were efficacious, especially those from new leaves; the ethanol extract from them caused the greatest mortality. The highest concentrations of the water and ethanol extracts (3.4 and 4.8% w/v, respectively) caused average mortality of 100 and 88.9% with new leaf extracts, and 94.7 and 86.4% with mature ones, respectively. The insecticide effectiveness 6 d after treatment in decreasing order were: new-ethanol (LC50 = 0.79% w/v), new-water (LC50= 2.08% w/v), mature-ethanol (LC50=0.63% w/v) mature-water (LC50=12.01% w/v). The LT50 at 1.7% w/v was 5.2 d. These results of the insecticide effect on G. platensis larvae allow to consider the leaf extracts from S. molle an interesting alternative as a bioinsecticide source for integrated pest management of this pest.

Los efectos que tienen los incendios en los ecosistemas forestales son variables, dependiendo de diversos factores entre los cuales se encuentra la severidad del fuego. Lo cual, a su vez, repercute en su recuperación. Sin embargo, evaluar áreas afectadas por fuego directamente en campo implica alta inversión de recursos que, junto con el tiempo, son generalmente limitados. No obstante, para la planeación de las estrategias de manejo y de restauración es necesario tener conocimiento del impacto del fuego. Para esto, los sensores remotos son una herramienta práctica para la evaluación de grandes áreas, o áreas inaccesibles, impactadas por incendios forestales. Cuyo uso va en aumento, siguiendo diferentes perspectivas de evaluación, como son el espectro infrarrojo, la detección de vegetación, ubicación de cenizas, etc. Por lo que para saber cuál es la mejor alternativa en el estudio de incendios forestales, es necesario conocer toda la gama de posibilidades y de esta manera poder elegir la más conveniente. Debido a esto, en este trabajo se hace una revisión de diferentes propuestas de evaluación de áreas impactadas por incendios forestales a través de sensores remotos. Las cuales se definen, principalmente, en una serie de índices espectrales, con base a los cuales, directa o indirectamente, se pretende no solo ubicar y dimensionar los incendios forestales, sino, en algunos casos, determinar el nivel de severidad. De esta forma, en este documento se agrupan las principales propuestas, con base a sus objetivos de detección de áreas impactadas: vegetación, suelo, agua, área quemada y radar.

It is possible, in both economic and technical terms, to sustainably manage Amazonian forests. Uhl et al describe research on wood sector patterns and trends, and the best management and regulation practices.

In this article, the authors review patterns of disturbance and succession in natural forests in the Coastal Northwest and compare structure and composition across an age gradient of unmanaged stands. Stand and landscape patterns in managed forests are then examined and compared with those in natural forests. They draw on the results to offer guidance on the management of Coastal Northwest forests that are dedicated to both wood production and conservation of biodiversity. Finally, the authors suggest that the lessons learned from natural forests here may be useful in other biomes, where unmanaged forests are rare and standards for designing seminatural forests are not available.

Models of community organization involve variations of the top-down (predator control) or bottom-up (nutrient limitation) hypotheses. Verbal models, however, can be interpreted in different ways leading to confusion. Therefore, we predict from first principles the range of possible trophic level interactions, and define mathematically the instantaneous effects of experimental perturbations. Some of these interactions are logically and biologically unfeasible. The remaining set of 27 feasible models is based on an initial assumption, for simplicity, of linear interactions between trophic levels. Many more complex and non-linear models are logically feasible but, for parsimony, simple ones are tested first. We use an experiment in the boreal forest of Canada to test predictions of instantaneous changes to trophic levels and distinguish between competing models. Seven different perturbations systematically removed each trophic level or, for some levels, supplemented them. The predictions resulting from the perturbations were concerned with the direction of change in biomass in the other levels. The direct effects of each perturbation produced strong top-down and bottom-up changes in biomass. At both the vegetation and herbivore levels top-down was stronger than bottom-up despite some compensatory growth stimulated by herbivory. The combination of experiments produced results consistent with two-way (reciprocal) interactions at each level. Indirect effects on one or two levels removed from the perturbation were either very weak or undetectable. Top-down effects were strong when direct but attenuated quickly. Bottom-up effects were less strong but persisted as indirect effects to higher levels. Although the 'pure reciprocal' model best fits our results for the boreal forest system different models may apply to different ecosystems around the world.

In this book, an ornithologist and a forester have combined their skills to try and tease out the real facts behind the various arguments on forestry.The conflict between forestry and nature conservation has become a major environmental issue in Britain in the 1980s.

Ecologists have advocated retaining various densities of canopy trees in harvest units in Pacific Northwest forests. In contrast to clear-cutting, this practice may better emulate the patterns of disturbance and structural complexity typical of natural forests in the region. Several ecological attributes, including vertebrate habitat diversity, are thought to be associated with stands of complex structure. The goal of this study was to determine bird abundance in canopy retention sites relative to other common stand types in the Pacific Northwest and to develop habitat functions for extrapolating bird abundance across current and future landscapes. We used data from five previous studies in the west central Cascades of Oregon to compare bird abundance and to develop habitat functions for forest birds across a wide range of natural and managed stand structures and ages. The 67 stands included clearcuts, retention sites, young closed-canopy plantations, mature stands, and old-growth stands. ANOVA revealed that 18 of the 23 species included in the analysis differed significantly in abundance among the stand types, with some species being primarily associated with each of the stand types. The habitat variables used to build habitat functions included tree density by size class, mean tree diameter, and variation in tree diameter. Linear, polynomial, and various nonlinear regression models were evaluated for each bird species. Significant habitat functions were generated for 17 of the 23 bird species. The analyses identified four habitat-use guilds among the 17 bird species: open-canopy; open-canopy with dispersed large trees; structurally complex closed-canopy; and structurally simple closed-canopy guilds. This study is the first in the Pacific Northwest to compare bird abundances across natural stands, traditionally managed plantations, and stands managed under ecological forestry approaches. The results suggested that canopy tree retention benefits many, but not all, of the bird species we studied, Moreover, the nonlinear responses of bird abundance revealed thresholds in tree density at which bird abundance changed dramatically. Knowledge of these thresholds allow managers to design stands for specific biodiversity objectives. The habitat functions presented here can be used to predict bird abundance based on habitat measurements derived from field data, remotely sensed data, or output from computer models of forest dynamics.

Socio-economic changes throughout history have shaped the attitude towards the forest and most significant ones are changes in terms of population. Over the centuries population and population density have had a significant impact on deforestation and the reduction of forest areas. Therefore, it is important to check what kind of trends are concerned and how population growth affects forest areas, forest cover and forest area per capita. These elements are important for assessing the direction, intensity of activity and the degree of success in the implementation of all forest policy measures in Serbia.