Search results for "Earth"

Intégrer la connectivité paysagère dans la séquence ERC : une approche par la quantité d'habitat atteignable

2019

Des engagements nationaux, européens et internationaux ont été pris pour maintenir et restaurer la connectivité entre habitats naturels face à la perte et à la fragmentation de ces habitats. Dans le même temps, les politiques environnementales dans différents pays mettent en oeuvre la séquence Eviter-Réduire-Compenser (ERC) pour atteindre l’objectif d’absence de perte nette de biodiversité (PPN). La séquence ERC a pour principe d’évaluer l’ensemble des impacts écologiques d’un aménagement, mais les critères et indicateurs permettant de quantifier les impacts sur la connectivité paysagère ne sont pas satisfaisants. Nous proposons une démarche opérationnelle pour évaluer les impacts environne…

The relevance of urban agroforestry and urban remnant forest for avian diversity in a densely-populated developing country: the case of Port-au-Princ…

2021

9 pages; International audience; Urban green spaces can contribute to conserve some of the original avian diversity in urbanized landscapes. However, the relative contribution of urban agriculture vs. urban forest remnants to the preservation of the avifauna in large cities, particularly in developing countries in the tropics, remains poorly documented. We assessed bird assemblages in the densely-populated capital city of Port-au-Prince in Haiti, one of the poorest countries in the world. From early January to late April 2018, 10 censuses per site were conducted in 16 urban green sites, consisting of 8 unexploited, private forest patches and 8 agroforestry plantations, embedded within the u…

Wetting Patterns Estimation Under Subsurface Drip Irrigation Systems for Different Discharge Rates and Soil Types

2018

Knowledge about the moisture distribution pattern shape and volume of soil wetted by an emitter is the basic need for better subsurface drip irrigation system. The dimensions of the pattern are imperative in selecting the right spacing between emitters and the suitable distance between laterals.

Life-cycle switching and coexistence of species with no niche differentiation.

2011

The increasing evidence of coexistence of cryptic species with no recognized niche differentiation has called attention to mechanisms reducing competition that are not based on niche-differentiation. Only sex-based mechanisms have been shown to create the negative feedback needed for stable coexistence of competitors with completely overlapping niches. Here we show that density-dependent sexual and diapause investment can mediate coexistence of facultative sexual species having identical niches. We modelled the dynamics of two competing cyclical parthenogens with species-specific density-dependent sexual and diapause investment and either equal or different competitive abilities. We show th…

Descriptors of Posidonia oceanica meadows: Use and application

2005

This work benefited partly from the financial support of the European program ΓNTERREG IIIA Corsica, Sardinia. Tuscany

The role of noise on the steady state distributions of phytoplankton populations

2016

The spatio-temporal behaviour of total chlorophyll concentration is investigated in the middle of the Tyrrhenian Sea by using a stochastic approach. The study is based on a reaction-diffusion-taxis model, which is used to analyse the dynamics of five phytoplankton groups, responsible for about 80% of the total chlorophyll a inside the euphotic zone of the water column. The analysis is performed by considering: (i) the intraspecific competition of the phytoplanktonic groups for limiting factors, i.e. light intensity and nutrient concentration, (ii) the seasonal changes of environmental variables, and (iii) the random fluctuations of the components of the velocity field and temperature. Speci…

Spatio-Temporal model structures with shared components for semi-continuous species distribution modelling

2017

Abstract Understanding the spatio-temporal dynamism and environmental relationships of species is essential for the conservation of natural resources. Many spatio-temporally sampled processes result in continuous positive [ 0 , ∞ ) abundance datasets that have many zero values observed in areas that lie outside their optimum niche. In such cases the most common option is to use two-part or hurdle models, which fit independent models and consequently independent environmental effects to occurrence and conditional-to-presence abundance. This may be correct in some cases, but not as much in others where the detection probability is related to the abundance. The aim of this work is to infer the…

Salinity and periodic inundation controls on the soil-plant-atmosphere continuum of gray mangroves

2017

Salinity and periodic inundation are both known to have a major role in shaping the ecohydrology of mangroves through their controls on water uptake, photosynthesis, stomatal conductance, gas-exchanges and nutrient availability. Salinity, in particular, can be considered one of the main abiotic regulating factors for halophytes and salt tolerant species, due to its influence on water use patterns and growth rate. Ecohydrological literature has rarely focused on the effects of salinity on plant transpiration, based on the fact that the terrestrial plants mostly thrive in low saline, unsaturated soils where the role of osmotic potential can be considered negligible. However, the effect of sal…

2021

Sustainable forest management plays a key role for forest biodiversity and the provisioning of ecosystem services (BES), including the important service of carbon sequestration for climate change mitigation. Forest managers, however, find themselves in the increasingly complex planning situation to balance the often conflicting demands in BES. To cope with this situation, a prototype of a decision support system (DSS) for strategic (long-term) planning at the forest enterprise level was developed in the present project. The DSS was applied at three case study enterprises (CSEs) in Northern Switzerland, two lowland and one higher-elevation enterprise, for a 50-year time horizon (2010 to 2060…

Sucrose amendment enhances phytoaccumulation of the herbicide atrazine in Arabidopsis thaliana.

2006

International audience; Growth in the presence of sucrose was shown to confer to Arabidopsis thaliana (thale cress or mustard weed) seedlings, under conditions of in vitro culture, a high level of tolerance to the herbicide atrazine and to other photosynthesis inhibitors. This tolerance was associated with root-to-shoot transfer and accumulation of atrazine in shoots, which resulted in significant decrease of herbicide levels in the growth medium. In soil microcosms, application of exogenous sucrose was found to confer tolerance and capacity to accumulate atrazine in Arabidopsis thaliana plants grown on atrazine-contaminated soil, and resulted in enhanced decontamination of the soil. Applic…