Structural effects of reedbed grazing and its cessation on reed-nesting songbird densities

Reedbeds are crucial breeding habitats for vulnerable songbird species.Irrespective of their protection status,these habitats may be threatened by organic matter accumulation,progressively leading to structural homoge-nization and habitat succession towards woodland.Managers prevent excessive litter build-up with various in-terventions opening-up the reedbeds,such as grazing,which may be detrimental or suitable for some reed bird species.We assessed the effects of extensive grazing by horses and its cessation in the medium and long terms on reedbed structure,and the consequences on reed-nesting songbird densities in Estagnol Nature Reserve,a pro-tected wetland near the French Mediterranean coast.We compared reedbed structural features between grazed,newly ungrazed and old-ungrazed plots.During nine years,we censused four songbird species in spring and collected water level data in the same survey plots.Grazing reduced reedbed extent,rejuvenated the vegetation with more short green stems on a thinner litter,and produced higher structural heterogeneity and discontinuity compared to long-lasting non grazing.Newly ungrazed plot showed intermediate effects.All surveyed songbird total densities were similar among plots while species numbers and densities differed.Grazed reedbed was more attractive to Moustached Warblers(Acrocephalus melanopogon)and Great Reed Warblers(Acrocephalus arundi-naceus),likely due to the large edges and the high vegetation structural heterogeneity.However,Moustached Warblers were more negatively affected by higher water level in grazed reedbed,presumably because flooding prevents litter foraging.The newly ungrazed reedbed was not preferred by any species.All warbler species were found under low density in the old-ungrazed reedbed,where Reed Buntings(Emberiza schoeniclus)were exclu-sively found.Food availability related to thick litter layer may explain this predilection.Common Reed Warblers(Acrocephalus scirpaceus)were found everywhere in similar densities.We conclude that reedbed management by extensive horse grazing and also its long-term cessation may benefit several songbird species.Within a context of wetland degradation and disappearance,both management strategies are useful to establish and maintain suitable habitats for reed-nesting songbird communities.

Production of micro-cuttings from acorns to test the plasticity of response to contrasting soil water regimes

We collected acorns from selected Quercus robur and Quercus petraea mother trees growing at sta- tions with different depths to the water table. We produced pairs of micro-cuttings from these single acorns. The obtained pairs of cuttings represented phenotypes of high similarity according to photosynthetic parameters. These pairs of cuttings were used to test the plasticity of response to contrasting water regimes. For each pair, one cutting was submitted to drought and the other was submitted to waterlogging. Drought response was recorded according to gas exchange traits （stomatal closure and water use effi- ciency）. The response to waterlogging was recorded according to the capacity to form hypertrophied lenticels and to maintain the CO2 assimilation rate. Intermediary phenotypes presenting both high water use efficiency and the capacity to develop hypertrophied lenticels were expected.

Temporo-spatial dynamics and behavioural patterns of 2012 cholera epidemic in the African mega-city of Conakry,Guinea

Background:Cholera is endemic in Guinea,having suffered consecutive outbreaks from 2004 to 2008 followed by a lull until the 2012 epidemic.Here we describe the temporal-spatial and behavioural characteristics of cholera cases in Conakry during a three-year period,including the large-scale 2012 epidemic.Methods:We used the national and African Cholera Surveillance Network(Africhol)surveillance data collected from every cholera treatment centre in Conakry city from August 2011 to December 2013.The prevalence of suspect and confirmed cholera cases,the case fatality ratio(CFR),and the factors associated with suspected cholera were described according to three periods:pre-epidemic(A),epidemic 2012(B)and post epidemic(C).Weekly attack rates and temporal-spatial clustering were calculated at municipality level for period B.Cholera was confirmed by culture at the cholera national reference laboratory.Results:A total of 4559 suspect cases were reported:66,4437,and 66 suspect cases in periods A,B and C,respectively.Among the 204 suspect cases with culture results available,6%,60%,and 70%were confirmed in periods A,B,and C,respectively.With 0.3%,the CFR was significantly lower in period B than in periods A(7.6%)and C(7.1%).The overall attack rate was 0.28%in period B,ranging from 0.17%to 0.31%across municipalities.Concomitantly,a cluster of cases was identified in two districts in the northern part of Conakry.At 14%,rice water stools were less frequent in period A than in period B and C(78%and 84%).Dehydration(31%vs 94%and 89%)and coma(0.4%vs 3.1%and 2.9%)were lower during period B than in periods A and C.The treatment of drinking water was less frequent in period A,while there were more reports of recent travel in period C.Conclusions:The epidemic dynamic and the sociological description of suspect cases before,during,and after the large-scale epidemic revealed that the Vibrio cholerae was already present before the epidemic.However,it appeared that infected individuals reacted differently in terms of disease severity as well as their access to treated water and travel habits.Such an in-depth description of cholera epidemics should be systematically carried out in cholera endemic settings in order to prioritize higher risk areas,identify transmission factors,and optimize preventive interventions.

Chaos in DNA evolution

In this paper, we explain why the chaotic mutation （CM） model of J. M. Bahi and C. Michel （2008） simulates the genes mutations over time with good accuracy. It is firstly shown that the CM model is a truly chaotic one, as it is defined by Devaney. Then, it is established that mutations occurring in genes mutations have indeed a same chaotic dynamic, thus making relevant the use of chaotic models for genomes evolution. Transposition and inversion dynamics are finally investigated.