Search results for "Life on Land"

2015

Prey preference of top predators and energy flow across habitat boundaries are of fundamental importance for structure and function of aquatic and terrestrial ecosystems, as they may have strong effects on production, species diversity, and food-web stability. In lakes, littoral and pelagic food-web compartments are typically coupled and controlled by generalist fish top predators. However, the extent and determinants of such coupling remains a topical area of ecological research and is largely unknown in oligotrophic high-latitude lakes. We analyzed food-web structure and resource use by a generalist top predator, the Arctic charr Salvelinus alpinus (L.), in 17 oligotrophic subarctic lakes…

Placing unprecedented recent fir growth in a European-wide and Holocene-long context

2014

7 páginas.- Büntgen, U.

Optimal Sustainable Policies Under Pollution Ceiling: the Demographic Side

2014

AD; International audience; We study optimal sustainable policies in a benchmark logistic world (where both population and technological progress follow logistic laws of motion) subject to a pollution ceiling. The main policy in the hands of the benevolent planner is pollution abatement, ultimately leading to the control of a dirtiness index as in the early literature of the limits to growth literature. Besides inclusion of demographic dynamics, we also hypothesize that population size affects negatively the natural regeneration or assimilation rate, as a side product of human activities (like increasing pollution, deforestation, ...). We first characterize optimal sustainable policies. Und…

Carbon sequestration in French agricultural soils: A spatial economic evaluation

2021

International audience; Soil organic carbon sequestration measures entail costs to farmers with different individual characteristics and located in different areas. A cost‐effective analysis taking into account these heterogeneities is crucial for developing effective public policy aimed at increasing carbon sequestration. We undertake such an analysis focusing on three soil organic carbon sequestration measures: no‐till, extension of temporary grasslands, and hedgerows. Through an optimization model applied to France, our results show that only extension of temporary grasslands can store carbon at low cost, though their potential for carbon sequestration is also low. For an ambitious carbo…

GIS-based hedonic pricing of landscape

2009

ACL; International audience; Hedonic prices of landscape are estimated in the urban fringe of Dijon (France). Viewshed and its content as perceived at ground level are analyzed from satellite images supplemented by a digital elevation model. Landscape attributes are then fed into econometric models (based on 2,667 house sales) that allows for endogeneity, multicollinearity, and spatial correlations. Results show that when in the line of sight, trees and farmland in the immediate vicinity of houses command positive prices and roads negative prices; if out of sight, their prices are markedly lower or insignificant: the view itself matters. The layout of features in fragmented landscapes comma…

Symposium on “Climate Change and Molluscan Ecophysiology” at the 79thAnnual Meeting of the American Malacological Society

2015

Climate change has already had many observable effects on Earth. On land, glaciers and snowpacks have shrunk, tropical forests are being replaced by savannahs, and coastal areas have increased risks of flooding (e.g., IPCC 2007, Allan and Soden 2008, Dai 2010, NOAA 2010, Chen et al. 2011). In addition to sea-surface warming, climate change has altered the physical and chemical nature of the marine environment, including ocean acidification and expanding hypoxia. The scope and scale of future environmental change that individuals will undergo on land and in the sea will fundamentally influence the ecological and evolutionary responses of populations and species, dependent on their evolved ph…

Linear relationship between effective radius and precipitation water content near the top of convective clouds: measurement results from ACRIDICON–CH…

2021

Quantifying the precipitation within clouds is a crucial challenge to improve our current understanding of the Earth's hydrological cycle. We have investigated the relationship between the effective radius of droplets and ice particles (re) and precipitation water content (PWC) measured by cloud probes near the top of growing convective cumuli. The data for this study were collected during the ACRIDICON–CHUVA campaign on the HALO research aircraft in clean and polluted conditions over the Amazon Basin and over the western tropical Atlantic in September 2014. Our results indicate a threshold of re∼13 µm for warm rain initiation in convective clouds, which is in agreement with previous studie…

Ecological Indicator Values of Europe (EIVE) 1.0: A Powerful Open-Access Tool for Vegetation Scientists

2016

International audience; Background: Ecological indicator values (EIVs) have a long tradition in vegetation ecological research in Europe. EIVs characterise the ecological optimum of species along major environmental gradients using ordinal scales. Calculating mean indicator values per plot is an effective way of bioindication. Following first systems in Russia and Central Europe, about two dozen EIV systems have been published for various parts of Europe.Aims: As there was no EIV system available at European scale that could be used for broad- scale analyses, e.g. in the context of the European Vegetation Archive (EVA), we develop such a system for the first time for the vascular plants of …

Comparison Between Fractional Vegetation Cover Retrievals from Vegetation Indices and Spectral Mixture Analysis: Case Study of PROBA/CHRIS Data Over …

2009

Abstract: In this paper we compare two different methodologies for Fractional Vegetation Cover (FVC) retrieval from Compact High Resolution Imaging Spectrometer (CHRIS) data onboard the European Space Agency (ESA) Project for On-Board Autonomy (PROBA) platform. The first methodology is based on empirical approaches using Vegetation Indices (VIs), in particular the Normalized Difference Vegetation Index (NDVI) and the Variable Atmospherically Resistant Index (VARI). The second methodology is based on the Spectral Mixture Analysis (SMA) technique, in which a Linear Spectral Unmixing model has been considered in order to retrieve the abundance of the different constituent materials within pixe…

The role of plant species on runoff and soil erosion in a Mediterranean shrubland.

2021

Shrubland is a Mediterranean biome characterized by densely growing evergreen shrubs adapted to fire events. To date, scientific research has focused on the impact of vegetation on soil erosion mainly through the control that plant biomass or plant cover exerts on sediment delivery and runoff discharge, being the individual plant species influence on hydrological and erosional processes not achieved in detail. The objective of this research is to determine: i) runoff and soil losses in a shrubland-covered rangeland at Sierra de Enguera, Spain; and ii) how four plant species affect soil and water losses. We measured soil cover, soil properties, runoff discharge and sediment yield under natur…