University of Antananarivo

About: University of Antananarivo is a education organization based out in Antananarivo, Madagascar. It is known for research contribution in the topics: Population & Lemur. The organization has 1561 authors who have published 1703 publications receiving 30922 citations. The organization is also known as: Tananarive University & Antananarivo University.

Larger bioavailability of soil phosphorus for irrigated rice compared with rainfed rice in Madagascar: results from a soil and plant survey

Abstract: Irrigated rice is less prone generally to phosphorus (P) deficiency than rainfed rice because redox reactions release P upon soil flooding. It is not known whether that is also true in highly weathered soils of Madagascar where the combination of high soil Fe and low P input may impede significant release of P. Soils and flag leaf samples were collected in 2010 in 38 irrigated rice and 46 rainfed rice fields belonging to private farmers. A critical flag leaf P content was derived from a P-dosed pot trial study with three soils, and the results suggested 2.4 g P/kg as the critical value. Average flag leaf P was significantly larger in irrigated than in rainfed rice (2.2 compared with 1.7 g P/kg), and flag leaf P was below the critical value in 76% of irrigated rice fields while this fraction was 100% in rainfed rice. Nitrogen and K deficiencies were less prevalent. Flag leaf P increased with increasing soil pH and soil pH explained partially differences in leaf P between irrigated and rainfed rice. Flag leaf P was unrelated to soil organic matter, but increased with oxalate-extractable soil P (Po). Multiple regression analysis revealed greater leaf P at equal soil Po and equal pH in irrigated compared with rainfed rice. Grain yield estimates (1-m2 squares) increased with flag leaf P but not with leaf N and K. In a regression model, about 42 % of the yield variance was explained with soil Po and a rice-growing system. The survey suggests that P is the main limiting nutrient for rice, and that soil P bioavailability is larger for irrigated than for rainfed rice in weathered soils of Madagascar.

The sweet and the bitter: Intertwined positive and negative social impacts of a biodiversity offset

Abstract: Major developments, such as mines, will often have unavoidable environmental impacts. In such cases, investors, governments, or even a company's own standards increasingly require implementation of biodiversity offsets (investment in conservation with a measurable outcome) with the aim of achieving 'no net loss' or even a 'net gain' of biodiversity. Where conservation is achieved by changing the behaviour of people directly using natural resources, the offset might be expected to have social impacts but such impacts have received very little attention. Using the case study of Ambatovy, a major nickel mine in the eastern rainforests of Madagascar and a company at the vanguard of developing biodiversity offsets, we explore local perceptions of the magnitude and distribution of impacts of the biodiversity offset project on local wellbeing. We used both qualitative (key informant interviews and focus group discussions) and quantitative (household survey) methods. We found that the biodiversity offsets, which comprise both conservation restrictions and development activities, influenced wellbeing in a mixture of positive and negative ways. However, overall, respondents felt that they had suffered a net cost from the biodiversity offset. It is a matter of concern that benefits from development activities do not compensate for the costs of the conservation restrictions, that those who bear the costs are not the same people as those who benefit, and that there is a mismatch in timing between the immediate restrictions and the associated development activities which take some time to deliver benefits. These issues matter both from the perspective of environmental justice, and for the long-term sustainability of the biodiversity benefits the offset is supposed to deliver.

Not rare, but threatened: the endemic Madagascar flying fox Pteropus rufus in a fragmented landscape

Abstract: The endemic Madagascar flying fox Pteropus rufus is threatened by habitat loss at roost sites and hunting for bushmeat. There is no conservation plan for this species, even though it is categorized on the IUCN Red List as Vulnerable and plays an important role as a seed disperser. In the Mangoro valley of central eastern Madagascar we monitored roost occupancy and abun- dance of P. rufus on 15 occasions at six sites over a 12- month period and conducted a detailed assessment of eight roosts during July 2004. There was considerable monthly variation in bat abundance and only two sites contained bats during every visit. Three sites were occupied only between September and March and may act as maternity or nursery roosts. Evidence of hunting was found at three roosts, and fire and forest clearance are ubiquitous threats. Two roosts were in Eucalyptus plantations and six were in small (2.2 - 28.7 ha) isolated fragments of degraded, mid elevation dense humid forest. All roosts were outside protected areas but were within 20 km of relatively intact forest. Faecal analysis revealed a diet of native forest tree species, cultivated fruits and Eucalyptus flowers. P. rufus in the Mangoro valley, and elsewhere in Madagascar, appears to survive in human-impacted environments by the inclusion of exotic plants in its diet and the ability to move between roosts. We provide conservation recommendations for P. rufus at both local and national levels.

The economic importance of freshwater crayfish harvesting in Madagascar and the potential of community-based conservation to improve management

Abstract: Madagascar's endemic freshwater crayfish (Parastacidae: Astacoides) are harvested by local people for both subsistence use and small-scale trade. There has been concern that populations, and even species, are threatened by overexploitation but little is known about the harvest or its economic importance. We studied crayfish exploitation in eastern Madagascar over 3 years. The existence of local taboos (fady) preventing commercial crayfish harvesting, as well as access to markets and forest, influenced involvement in the harvest. All four crayfish species found in the region were harvested, but A. granulimanus provided the majority of the catch. In one harvesting village more than 50% of the 47 households were directly involved in the harvest, which contributed USD 2,382 to the village economy in 2003/2004, an important sum in the context of local incomes. Subsistence use was widespread, particularly by children to whom it may provide an important protein source. Community-based conservation (through transfer of harvesting rights and responsibilities for forest management to local communities) is central to a new conservation paradigm in Madagascar. This recognizes communities' long term interest in their natural resources and offers an ideal opportunity for those concerned with the sustainability of the harvest to implement management tools (such as avoiding reproductive females, size limits and no-take zones). We discuss each tool with respect to biological implications and practical constraints. We note that community-based approaches may not be sufficient to conserve rarer species, which make up a small proportion of the value of the harvest.

Neutrino interaction classification with a convolutional neural network in the DUNE far detector

Abstract: The Deep Underground Neutrino Experiment is a next-generation neutrino oscillation experiment that aims to measure $CP$-violation in the neutrino sector as part of a wider physics program. A deep learning approach based on a convolutional neural network has been developed to provide highly efficient and pure selections of electron neutrino and muon neutrino charged-current interactions. The electron neutrino (antineutrino) selection efficiency peaks at 90% (94%) and exceeds 85% (90%) for reconstructed neutrino energies between 2-5 GeV. The muon neutrino (antineutrino) event selection is found to have a maximum efficiency of 96% (97%) and exceeds 90% (95%) efficiency for reconstructed neutrino energies above 2 GeV. When considering all electron neutrino and antineutrino interactions as signal, a selection purity of 90% is achieved. These event selections are critical to maximize the sensitivity of the experiment to $CP$-violating effects.