Tree-based intercropping systems increase growth and nutrient status of hybrid poplar: A case study from two Northeastern American experiments

Tree-based intercropping is considered to be a potentially useful land use system for mitigating negative environmental impacts from intensive agriculture such as nutrient leaching and greenhouse gas emissions. Rapid early growth of trees is critical for rapidly accruing environmental benefits provided by the trees. We tested the hypothesis that intercropping increases the growth and nutrient status of young hybrid poplars (Populus spp.), compared to a harrowing alley treatment (i.e., no intercrop), in two experimental sites (St-Rémi and St-Édouard) in southern Québec, Canada. Three hybrid poplar clones (TD3230, Populus trichocarpa × deltoides; DN3308, P. deltoides × nigra; and NM3729, P. nigra × maximowiczii) were planted at St-Rémi. Clones DN3333 and DN3570 were planted at St-Édouard. At St-Rémi, intercropping comprised a 4-year succession of three crops of soybean (Glycine max (L.) Merr.) and barley (Hordeum vulgare L.). At St-Édouard, intercropping comprised a 3-year succession of buckwheat (Fagopyrum esculentum Moench), winter rye (Secale cereale L.), and winter wheat (Triticum aestivum L.). At St-Rémi, four years after treatment began, leafless aboveground biomass of hybrid poplars in the intercropping treatment was 37% higher compared to that in the harrowing treatment. At St-Édouard, after the third growing season, leafless aboveground biomass of hybrid poplars in the intercropping treatment was significantly higher by 40%. Vector analysis of foliar nutrient concentrations and comparison with critical concentration values showed that N (both sites) and K (St-Édouard) were the most limiting nutrients. Hybrid poplar clones responded similarly to treatments, with no consistent differences in tree growth observed between clones. We conclude that tree-based intercropping systems may offer an effective means of improving the early growth of hybrid poplars planted to provide both environmental services and high-value timber.     

Bioaerosol sampling by a personal rotating cup sampler CIP 10-M

High concentrations of bioaerosols containing bacterial, fungal and biotoxinic matter are encountered in many workplaces, e.g. solid waste treatment plants, waste water treatment plants and sewage networks. A personal bioaerosol sampler, the CIP 10-M (M-microbiologic), has been developed to measure worker exposure to airborne biological agents. This sampler is battery operated; it is light and easy to wear and offers full work shift autonomy. It can sample much higher concentrations than biological impactors and limits the mechanical stress on the microorganisms. Biological particles are collected in 2 ml of liquid medium inside a rotating cup fitted with radial vanes to maintain an air flow rate of 10 l min(-1) at a rotational speed of approximately 7,000 rpm. The rotating cup is made of sterilisable material. The sampled particles follow a helicoidal trajectory as they are pushed to the surface of the liquid by centrifugal force, which creates a thin vertical liquid layer. Sterile water or another collecting liquid can be used. Three particle size selectors allow health-related aerosol fractions to be sampled according to international conventions. The sampled microbiological particles can be easily recovered for counting, incubation or further biochemical analysis, e.g., for airborne endotoxins. Its physical sampling efficiency was laboratory tested and field trials were carried out in industrial waste management conditions. The results indicate satisfactory collection efficiency, whilst experimental application has demonstrated the usefulness of the CIP 10-M personal sampler for individual bioaerosol exposure monitoring.     

A double‐edged sword: Realities of artisanal and small‐scale mining for rural people in the Alaotra region of Madagascar

A growing number of people are entering the artisanal and small‐scale mining (ASM) sector worldwide. In Madagascar, millions of individuals depend on this informal activity. Through a case study in the Alaotra‐Mangoro region of Madagascar, our research aimed to understand the “bottom‐up” dynamics and ripple effects of the sector, by looking at the realities for rural communities where inhabitants are both directly and indirectly affected by ASM. We were interested in community members' and miners' perceptions of the socio‐economic and environmental impacts of ASM, and in identifying the factors attracting people living in one of the country's agricultural hubs to this activity. Our results show a wide diversity of push and pull factors leading people to enter the sector. Although many positive impacts of ASM exist for miners and communities within the vicinity of mines, most miner participants considered themselves worse off since starting to mine, highlighting the high risk and low probability of return of ASM. ASM's potential for local and national development will remain squandered if its negative impacts continue to go unmanaged. Accounting for local contexts and the ripple effects of ASM will be crucial in achieving safety and security for miners, and to tap into the benefits it may offer communities while minimising environmental damage.     

A GIS-Based Multicriteria Evaluation for Aiding Risk Management <Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait. Forests: A Case Study in Corsican Island,Western Mediterranean Region

Forest management can benefit from decision support tools, including GIS-based multicriteria decision-aiding approach. In the Mediterranean region, Pinus pinaster forests play a very important role in biodiversity conservation and offer many socioeconomic benefits. However, the conservation of this species is affected by the increase in forest fires and the expansion of Matsucoccus feytaudi. This paper proposes a methodology based on commonly available data for assessing the values and risks of P. pinaster forests and to generating maps to aid in decisions pertaining to fire and phytosanitary risk management. The criteria for assessing the values (land cover type, legislative tools for biodiversity conservation, environmental tourist sites and access routes, and timber yield) and the risks (fire and phytosanitation) of P. pinaster forests were obtained directly or by considering specific indicators, and they were subsequently aggregated by means of GIS-based multicriteria analysis. This approach was tested on the island of Corsica (France), and maps to aid in decisions pertaining to fire risk and phytosanitary risk (M. feytaudi) were obtained for P. pinaster forest management. Study results are used by the technical offices of the local administration—Corsican Agricultural and Rural Development Agency (ODARC)—for planning the conservation of P. pinaster forests with regard to fire prevention and safety and phytosanitary risks. The decision maker took part in the evaluation criteria study (weight, normalization, and classification of the values). Most suitable locations are given to target the public intervention. The methodology presented in this paper could be applied to other species and in other Mediterranean regions.     

Isolation and characterization of mesotrione-degrading Bacillus sp. from soil

Dissipation kinetics of mesotrione, a new triketone herbicide, sprayed on soil from Limagne (Puy-de-Dôme, France) showed that the soil microflora were able to biotransform it.Bacteria from this soil were cultured in mineral salt solution supplemented with mesotrione as sole source of carbon for the isolation of mesotrione-degrading bacteria. The bacterial community structure of the enrichment cultures was analyzed by temporal temperature gradient gel electrophoresis (TTGE). The TTGE fingerprints revealed that mesotrione had an impact on bacterial community structure only at its highest concentrations and showed mesotrione-sensitive and mesotrione-adapted strains. Two adapted strains, identified as Bacillus sp. and Arthrobacter sp., were isolated by colony hybridization methods.Biodegradation assays showed that only the Bacillus sp. strain was able to completely and rapidly biotransform mesotrione. Among several metabolites formed, 2-amino-4-methylsulfonylbenzoic acid (AMBA) accumulated in the medium. Although sulcotrione has a chemical structure closely resembling that of mesotrione, the isolates were unable to degrade it.     

Frailty in state-space models: application to actuarial senescence in the Dipper

Senescence, a decrease in life history traits with age, is a within-individual process. The lack of suitable methods to deal with individual heterogeneity has long impeded progress in exploring senescence in wild populations. Analyses of survival senescence are additionally complicated by the often neglected issue of imperfect detectability. To deal with both these issues, we developed state-space models to analyze capture-mark-recapture data while accounting for individual heterogeneity by incorporating random effects. We illustrated our approach by applying it to 29 years of data on breeding females in a Dipper (Cinclus cinclus) population. We highlighted patterns of age-related variation in annual survival by statistical comparisons of piecewise linear, quadratic, Gompertz, and Weibull survival models. The Gompertz model was ranked first in our set. It provided strong evidence for actuarial senescence with an onset of senescence estimated at about 2.3 years. The probability for this model to involve a frailty was 0.15, and the probability to involve an individual latent effect in detection was about 0.4. The estimated mean age at first reproduction was 1.2 years. The general case model described here in detail should encourage the reanalysis of actuarial senescence in cases where imperfect detection or individual heterogeneity is suspected.