Variation in resource consumption across a gradient of increasing intra- and interspecific richness

Based on the premise that ecosystems with more species will function at more efficient rates, declining biodiversity is expected to alter important ecosystem functions, goods, and services across the globe. However, applicability of this general hypothesis to genetic or clonal richness in assemblages composed of few species is understudied. This illustrates the need to expand the focus of biodiversity-ecosystem-function experiments across all levels of biological diversity (including genetic). To explore this generality, we manipulated intraspecific (clonal) and interspecific (species) richness of a primary consumer, Daphnia, and measured assemblage feeding rate and total resource consumption. Our results showed that greater clonal richness had no effect on Daphnia feeding, and greater species richness decreased feeding-related effects of Daphnia. This suggests that multiclonal Daphnia assemblages may be no more efficient at consuming resources than monocultures, and that monocultures of Daphnia may consume resources more efficiently than more species-rich assemblages. The inhibitory effect of increasing richness observed in this study resulted from chemical and mechanical interference among some of the Daphnia taxa. This suggests that consumer-mediated ecosystem functions could be reduced when assemblages include taxa equipped with adaptations for interference competition.     

Transient dynamics of invasive competition: barred owls, spotted owls, habitat, and the demons of competition present

The recent range expansion of Barred Owls (Strix varia) into the Pacific Northwest, where the species now co-occurs with the endemic Northern Spotted Owl (Strix occidentalis caurina), resulted in a unique opportunity to investigate potential competition between two congeneric, previously allopatric species. The primary criticism of early competition research was the use of current species' distribution patterns to infer past processes; however, the recent expansion of the Barred Owl and the ability to model the processes that result in site occupancy (i.e., colonization and extinction) allowed us to address the competitive process directly rather than inferring past processes through current patterns. The purpose of our study was to determine whether Barred Owls had any negative effects on occupancy dynamics of nesting territories by Northern Spotted Owls and how these effects were influenced by habitat characteristics of Spotted Owl territories. We used single-species, multi-season occupancy models and covariates quantifying Barred Owl detections and habitat characteristics to model extinction and colonization rates of Spotted Owl pairs in southern Oregon, USA. We observed a strong, negative association between Barred Owl detections and colonization rates and a strong positive effect of Barred Owl detections on extinction rates of Spotted Owls. We observed increased extinction rates in response to decreased amounts of old forest at the territory core and higher colonization rates when old-forest habitat was less fragmented. Annual site occupancy for pairs reflected the strong effects of Barred Owls on occupancy dynamics with much lower occupancy rates predicted for territories where Barred Owls were detected. The strong Barred Owl and habitat effects on occupancy dynamics of Spotted Owls provided evidence of interference competition between the species. These effects increase the importance of conserving large amounts of contiguous, old-forest habitat to maintain Northern Spotted Owls in the landscape.     

The impact of high level gamma radiation on immobilized waste forms in polymeric matrices

A new polymer-based composite binder was developed for the containment/immobilization of radioactive waste forms. This material was subjected to a variety of physicochemical tests to determine its suitability for this purpose. It appears that this composite material possesses superior qualities in terms of resisting radiation damage, retaining the radio isotopes after radiation exposure, and resisting biodegradation. Further, a combination of chemical fixation/immobilization technology with the radiation-resistant binder was studied. Our evaluation procedures, the results, and its potential applications based on our conclusions are presented in this article.     

'Capacity for Change': Testing a Model for the Inclusion of Social Indicators in Australia's National Land and Water Resources Audit

The complexity of relationships between social change and natural resource management has generated interest in the identification of indicators that might provide more streamlined means for monitoring and planning. In the case of Australia's National Land and Water Resources Audit, interest has focused on the capacity of resource managers to implement more sustainable resource-use practices. This paper reports on an attempt to develop indicators of 'capacity for change' that are statistically reliable and both meaningful and useful to resource managers at a variety of scales. It will be argued, however, that social, spatial and temporal variability in change processes means that no discrete list of social indicators can achieve this task. At the same time that rigorous testing is needed to challenge common-sense assumptions about who is capable of change and where to target capacity-building programmes, data collection and interpretation must be embedded in processes of ongoing negotiation and adaptation among all those involved in, or affected by, resource management.     

Involving local farmers in rehabilitation of degraded tropical forests: some lessons from Ghana

The role of community-based plantation development in forest rehabilitation and poverty alleviation is a pressing issue for the government of Ghana. In this paper, we present an analysis of the prospects of a community-based plantation using taungya systems and indigenous trees as means to forest rehabilitation and livelihood improvement in Ghana. The project management strategies, communication process and incentive mechanism and their impact on local participation are discussed with the aim to recommending a mechanism through which local farmers can best be involved in rehabilitation of degraded sites in the future in Ghana. Data were collected through a survey using personal interviews of 431 farming households and ten key informants from ten communities living in scattered hamlets in and around forests reserves. The results show a high rate of local participation in project tree planting activities. Four years after the project’s initiation, about 250 ha of plantations had been established using twelve priority indigenous and one exotic species and farmers had indicated improvement in their farming practices and availability of food and forest products. Restoring forest quality as a timber resource and associated values, getting money, food stuff and timber and non-timber for domestic use, and having access to fertile land for farming were the top three issues prioritised by respondents as motivational factors for engaging in the project activities. Overall, this project demonstrates that reversing tropical forest degradation is possible. For this we need local involvement in tree domestication combined with activities that addresses livelihood needs and environmental concerns. This case also demonstrates the prospects of utilising indigenous tree species, not only exotic species that dominated tree planting in the past, for plantations and landscape rehabilitation in Ghana. Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue.     

Field-focusing nuclear magnetic resonance (FONAR)

A technique, field-focusing NMR (FONAR), is described for doing NMR scans in large samples. The method utilizes a shaped D.C. magnetic field that confines the NMR-signal-producing region of the sample to a small volume called the resonance aperture. The aperture contains the required values of the Ho field to fully bracket the band of the r.f. pulse. The magnet system and r.f. pick-up coil that achieved the first human NMR can is discussed.