The limited contribution of large trees to biomass dynamics in an old-growth tropical forest

Although the importance of large trees regarding biodiversity and carbon stock in old-growth forests is undeniable, their annual contribution to biomass dynamics and carbon uptake remains poorly studied at the stand level. To clarify the role of large trees in biomass dynamics, we used data of tree growth, mortality and recruitment monitored during 20 years in 10×4-ha plots in a species rich tropical forest (Central African Republic). Using a random block design, three different silvicultural treatments, control, logged, and logged + thinned, were applied in the 10 plots. Biomass gains and losses were analyzed in relation to the relative biomass abundance of large trees and by tree size classes using a spatial bootstrap procedure. Despite large trees showing a high individual growth rates and holding a substantial amount of biomass, we showed that stand-level biomass production decreased with the abundance of large trees in all treatments and plots. The contribution of large trees to annual stand-level biomass production appeared limited in comparison to that of small trees. This pattern did not only originate from differences in abundance of small versus large trees or differences in initial biomass stocks among tree size classes but also from a reduced relative growth rate of large trees and a relatively constant mortality rate among tree size classes. In a context in which large trees are increasingly gaining attention as being a valuable and a key structural characteristic of natural forests, the present study brought key insights to (1) better gauge the relatively limited role of large trees in the biomass dynamics at the stand level and (2) carefully up-scale results of biomass growth observed at the tree or species levels

How Tightly Linked Are Pericopsis elata (Fabaceae) Patches to Anthropogenic Disturbances in Southeastern Cameroon?

peer reviewedWhile most past studies have emphasized the relationships between specific forest stands and edaphic factors, recent observations in Central African moist forests suggested that an increase of slash-and-burn agriculture since 3000–2000 BP (Before Present) could be the main driver of the persistence of light-demanding tree species. In order to examine anthropogenic factors in the persistence of such populations, our study focused on Pericopsis elata, an endangered clustered timber species. We used a multidisciplinary approach comprised of botanical, anthracological and archaeobotanical investigations to compare P. elata patches with surrounding stands of mixed forest vegetation (“out-zones”). Charcoal samples were found in both zones, but were significantly more abundant in the soils of patches. Eleven groups of taxa were identified from the charcoals, most of them also present in the current vegetation. Potsherds were detected only inside P. elata patches and at different soil depths, suggesting a long human presence from at least 2150 to 195 BP, as revealed by our charcoal radiocarbon dating. We conclude that current P. elata patches most likely result from shifting cultivation that occurred ca. two centuries ago. The implications of our findings for the dynamics and management of light-demanding tree species are discussed

Prevalence of Bowel Damage Assessed by Cross-Sectional Imaging in Early Crohn's Disease and its Impact on Disease Outcome

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Afternoon shedding of a new species of Isospora

The Regent Honeyeater (Xanthomyza phyrigia) is an endangered Australian bird species. Breeding populations have been established at Australian zoos in support of re-introduction programs. This species is the host of a new species of Isospora (Apicomplexa). Oocysts are spherical, 25.8 (22.5- 28.75) by 23.8 (20-26.25) µm with a colourless to pale yellow smooth wall undergoing rapid exogenous sporulation, 90% sporulated oocysts in 8 hours at 20 C. Each oocyst contains one polar granule. Sporocysts are ovoid, 18.67 (17-19) by 9.49 (9-10) µm with a flat Stieda body and spherical substieda body devoid of a hyaline body. The asexual stages and sexual phase is within the enterocytes of the duodenum and jejunum. Faeces collected in the morning (AM, n=84) and in the afternoon (PM, n=90) revealed significant diurnal periodicity in oocyst shedding; 21% (18 of 84) of the AM were positive with the mean of 499 oocysts.g-1 compared to the PM with 91% (82 of 90) bird faeces positive with the mean of 129,723 oocysts.g-1. Therefore, parasite checks for these birds should be carried out in the afternoon to obtain an accurate result. In conclusion, it is plausible that captive birds with high parasite burdens could be less likely selected by females for reproduction after release due to their duller plumage than their wild counterparts. Keywords: coccidia, Isospora, Regent Honeyeater, honeyeater, diurnal shedding, oocysts, recovery program

Prospective scientifique pour la recherche française sur la biodiversité - 2023

Entre 2021 et 2022, le groupe Enjeux transversaux biodiversité (GET biodiversité) de l'Alliance nationale de recherche pour l'Environnement (AllEnvi) a travaillé à une prospective pour la recherche française sur la biodiversité. Depuis les derniers travaux publiés par la FRB en 2012, le paysage de la recherche sur la biodiversité a fortement évolué et une actualisation des projections et perspectives s'avérait nécessaire. Dans ce cadre, la Fondation pour la recherche sur la biodiversité a animé les discussions et coordonné la rédaction d'un document rassemblant membres des Conseils scientifiques de la FRB entre 2021 et 2023, experts du GET d'AllEnvi et collaborateurs externes. Le présent document constitue un travail d'identification, d'analyse et de catégorisation des différents axes de recherche en biodiversité sans pour autant en former une liste exhaustive et impartiale. Fondation de coopération scientifique, la Fondation pour la recherche sur la biodiversité a pour mission de favoriser les activités de recherche sur la biodiversité en lien avec les acteurs de la société. Susciter l'innovation, développer et soutenir des projets, diffuser les connaissances et mobiliser l'expertise sont au coeur de ses actions

Molecular and Biological Investigations of Tritrichomonas foetus from Cattle, Domestic Cats and Pigs

Few organisms have the potential to shed light on aspects of parasitism as much as Tritrichomonas foetus. While it is a commensal organism in pigs, T. foetus is a urogenital parasite of cattle and an intestinal parasite of domestic cats. In this thesis, I show that a high prevalence of porcine T. foetus is maintained in domestic pigs on an Australian farm where pigs and T. foetus-free cattle are farmed in close proximity. A novel Australian reference isolate of porcine T. foetus with close association to bovine T. foetus is established. Baseline transcriptomes of T. foetus from cattle, cat and pig hosts are sequenced and compared to confirm that isolates from the three hosts represent the same T. foetus species. In addition, significant differences are identified in the transcription of virulence factors between the bovine and feline isolates. To understand how the environment of the organ niche in individual hosts influence host choice and epidemiology of the two parasitic T. foetus, tolerance to extracelluar pH was investigated in vitro. The feline T. foetus demonstrated an enhanced capacity to maintain viability when exposed to mild acidic pH in contrast to bovine T. foetus, implying that pH is a barrier to cross-infection between the two hosts. An in silico investigation into plausible drug targets for the parasitic bovine and feline T. foetus revealed that drug targets chosen for more focused investigation in T. foetus originating from cattle may not be ideal for T. foetus in domestic cats. Having made large sequences databases available, this thesis attempts to expand the molecular toolbox for parasitologists working on anaerobes by trialling miniSOG, a flavin-based oxygen-independent fluorescent protein (FbFP) tag in T. foetus. As a whole, this body of work has created a platform to advance future T. foetus research in the fields of epidemiology, drug target discovery and recombinant protein tagging

Le préjudice d’anxiété

The judge, who has the task of interpreting the law in the context of legal actions, finds himself confronted with human situations in which emotions are present. Thus, the parties to an action sometimes invoke the anxiety that they may have felt in order to seek compensation for the resulting harm. The judge, who is not e a psychologist by profession, must in such a situation take a position on the compensation for the harm due to anxiety. While, in some situations, compensation for the harm linked to anxiety is accepted, such as in the case of exposure of an employee to asbestos or the wearing of a defective pacemaker, to date there is no general prejudice of anxiety that would apply identically in all branches of private law. In the absence of a definition of repairable damage as regards anxiety and of the details as to the conditions for reparation, there is a multiplicity of situations in which there are various rulings devoted to one and the same emotion, which is anxiety. The issue them is to propose a prejudice of anxiety that would make it possible to harmonise the jurisprudence.Le juge qui a vocation à interpréter le droit dans le cadre de litiges se trouve confronté à des situations humaines dans lesquelles les émotions sont présentes. Ainsi, les parties à un procès invoquent-elles parfois l'anxiété qu'elles ont pu ressentir avant de solliciter l'indemnisation du préjudice qui en résulte. Le juge, qui n'est pas un professionnel de la psychologie, doit pour autant prendre position sur la réparation de préjudices fondés sur l'anxiété. S'il admet la réparation de préjudices liés à l'anxiété dans différentes situations telles que l'exposition d'un salarié à l'amiante ou le port d'une sonde cardiaque défectueuse, à ce jour il n'existe pas de préjudice d'anxiété général qui aurait vocation à s'appliquer de manière identique dans toutes les branches du droit privé. En l'absence de définition de l'anxiété réparable et de précisions quant aux conditions de réparation, de multiples préjudices sont consacrés pour une seule et même émotion qu'est l'anxiété. L'enjeu est alors de proposer un préjudice d'anxiété permettant d'harmoniser la jurisprudence