Can forest management based on natural disturbances maintain ecological resilience?

Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance

Detecção de anticorpos para Toxoplasma gondii em soro de suínos criados e abatidos em frigoríficos da região da grande Porto Alegre-RS, Brasil Detection of antibodies against Toxoplasma gondii in sera from swine bred and slaughtered in the great Porto Alegre-RS abbattoirs, Brazil

No presente trabalho, objetivou-se contribuir com dados sobre a freqüência de sororeagentes para Toxoplasma gondii em suínos criados e abatidos na Região da Grande Porto Alegre e fornecer subsídios sobre a importância da transmissão deste protozoário, por suínos. Foram coletadas amostras de 240 suínos em frigoríficos da região. A freqüência de anticorpos anti- Toxoplasma gondii, determinada através da técnica de hemaglutinação indireta, foi de 20 % de soros iguais ou superiores a diluição 1:64. Na técnica de imunofluorescência indireta, foram encontrados 33,75% de soro com diluição iguais a 1:16 ou superiores.<br>This report objectived to contribuite with data about the antibodies occurence of Toxoplasma gondii in swine bred and slaughtered in the area of Great Porto Alegre- RS, Brazil. The data should supply with subsidies on the importance of this protozoan transmission through swines. Samples were taken from 240 swines at slaughterhouses in that region. The frequency of anti-Toxoplasma gondii antibodies, determinanet through the indirect hemagglutination technic was of 20% of serum equal or superior to 1:64 dilution. In the indirect immunofluorescence technic was found 33.75% in serum with a diluition equal to 1:16 or superior

The Craft of Policy Design: Can It Be More Than Art&quest;

The craft for predicting and evaluating the impacts of policy alternatives has received much of the attention of students of public policy analysis. Relatively little attention has been given to understanding and improving the craft for designing alternative policies. Beyond catalogs of generic policy instruments, two sources provide useful insights into policy design. First, the study of institutional choice as policy design draws attention to the selection of procedures and incentive systems to achieve substantive policy outcomes. Second, the study of the manipulation of the dimensions of policy choice (heresethetics), which provides insight into strategy in political arenas, may help with the broader problem of packaging and presenting policies so that they remain viable during implementation. Copyright 1992 by The Policy Studies Organization.