Search results for "Spatial heterogeneity"
showing 10 items of 71 documents
Energy density and its variation in space limit species richness of boreal forest birds
2012
Aim An area’s ability to support species may be dependent not only on the total amount of available energy it contains but also on energy density (i.e. available energy per unit area). Acknowledging these two aspects of energy availability may increase mechanistic understanding of how increased energy availability results in increased species richness. We studied the relationship between energy density, its variation in space and boreal forest bird species richness and investigated two possible mechanisms: (1) metabolic constraints of organisms, and (2) increased resource availability for specialists. Location Protected areas in Finland’s boreal forest. Methods We tested whether bird spe…
Small Mammals in Forests of Romania: Habitat Type Use and Additive Diversity Partitioning
2021
Small mammals are key components of forest ecosystems, playing vital roles for numerous groups of forest organisms: they exert bottom-up and top-down regulatory effects on vertebrate and invertebrate populations, respectively
An Exploratory Spatial Data Analysis of European Regional Disparities, 1980–1995
2003
European integration has stimulated numerous studies of regional economic convergence within the European Union in recent macroeconomic and regional science literature (e.g. Abraham and Von Rompuy 1995; Armstrong 1995a; Neven and Gouyette 1995; Martin 2001). Most of the time, the empirical methods that have been used are identical to the methods employed in international studies. However, spatial effects, particularly spatial autocorrelation and spatial heterogeneity, must be taken into account when analyzing the convergence process at regional scale. There are number of factors — trade between regions, technology, knowledge diffusion and more generally regional spillovers — that lead to ge…
Getting into the groove: Opportunities to enhance the ecological value of hard coastal infrastructure using fine-scale surface textures
2015
Concrete flood defences, erosion control structures, port and harbour facilities, and renewable energy infrastructure are increasingly being built in the world’s coastal regions. There is, however, strong evidence to suggest that these structures are poor surrogates for natural rocky shores, often supporting assemblages with lower species abundance and diversity. Ecological engineering opportunities to enhance structures for biodiversity conservation (and other management goals) are therefore being sought, but the majority of work so far has concentrated on structural design features at the centimetre–meter scale.\ud \ud We deployed concrete tiles with four easily-reproducible fine-scale (m…
Impact of historical mining assessed in soils by kinetic extraction and lead isotopic ratios.
2014
12 pages; International audience; The aim of this study is to estimate the long-term behaviour of trace metals, in two soils differently impacted by past mining. Topsoils from two 1 km(2) zones in the forested Morvan massif (France) were sampled to assess the spatial distribution of Cd, Cu, Pb and Zn. The first zone had been contaminated by historical mining. As expected, it exhibits higher trace-metal levels and greater spatial heterogeneity than the second non-contaminated zone, supposed to represent the local background. One soil profile from each zone was investigated in detail to estimate metal behaviour, and hence, bioavailability. Kinetic extractions were performed using EDTA on thre…
Changes in predator community structure shifts the efficacy of two warning signals in Arctiid moths
2013
Summary 1. Polymorphism in warning coloration is puzzling because positive frequency-dependent selection by predators is expected to promote monomorphic warning signals in defended prey. 2. We studied predation on the warning-coloured wood tiger moth (Parasemia plantaginis )b y using artificial prey resembling white and yellow male colour morphs in five separate populations with different naturally occurring morph frequencies. 3. We tested whether predation favours one of the colour morphs over the other and whether that is influenced either by local, natural colour morph frequencies or predator community composition. 4. We found that yellow specimens were attacked less than white ones rega…
Intra-urban spatial distributions of population and employment : the case of the agglomeration of Dijon, 1999
2003
The aim of this paper is to analyze the intra-urban spatial distributions of population and employment in the agglomeration of Dijon (regional capital of Burgundy, France). We study whether this agglomeration has followed the general tendency of job decentralization observed in most urban areas or whether it is still characterized by a monocentric pattern. In that purpose, we use a sample of 136 observations at the communal and at the IRIS (infra-urban statistical area) levels with 1999 census data and the employment database SIRENE (INSEE). First; we study the spatial pattern of total employment and employment density using exploratory spatial data analysis. Apart from the CBD, few IRIS ar…
Exploring the spatial relationship between airborne-derived red and far-red sun-induced fluorescence and process-based GPP estimates in a forest ecos…
2019
International audience; Terrestrial gross primary productivity (GPP) plays an essential role in the global carbon cycle, but the quantification of the spatial and temporal variations in photosynthesis is still largely uncertain. Our work aimed to investigate the potential of remote sensing to provide new insights into plant photosynthesis at a fine spatial resolution. This goal was achieved by exploiting high-resolution images acquired with the FLuorescence EXplorer (FLEX) airborne demonstrator HyPlant. The sensor was flown over a mixed forest, and the images collected were elaborated to obtain two independent indicators of plant photosynthesis. First, maps of sun-induced chlorophyll fluore…
Informational analysis of forest landscape spatial heterogeneity
1999
Summary Under the perspective of forest ecosystem management, landscape is interpreted as a functioning structure. From an inventory and monitoring operational point of view, such an approach implies wise use of geographic information systems and remote sensing techniques enabling a global view of the territorial mosaic. From a methodological point of view, landscape ecology theory may be used as the assessment framework. Remotely sensed data provide excellent opportunities for the involved analyses, using both vegetation density measures and spatial statistics. The objective of this paper was to assess landscape spatial heterogeneity using an analysis method based on Shannon's information …
The spatial dimension of the French private rental markets: Evidence from microgeographic data in 2015
2021
International audience; This article draws on data collected by local rental observatories in 12 French urban units in 2015 to analyze the spatial dimension of hedonic rental prices in the private rental market through (i) the spatial heterogeneity between urban units and (ii) the wide variety of contextual and locational characteristics (socio-economic, environmental (dis)amenity, and accessibility) and flexible specifications to capture their potential non-linear influence on rent. Based on a joint test of equality of coefficients across all urban units, we find that hedonic prices differ for 75% of the characteristics, thereby justifying a detailed analysis of heterogeneity. Lyon, Nice, …