Search results for "Spatial pattern"
showing 10 items of 54 documents
Mapping spatial patterns of denitrifiers for bridging community ecology and microbial processes along environmental gradients
2009
While there is ample evidence that microbial processes can exhibit large variations at a field scale, very little is known about the spatial distribution of the communities mediating these processes. The objective of this study was to explore spatial patterns of size and activity of the denitrifying community, a functional guild involved in N-cycling, in a grassland field subjected to different cattle grazing regimes. We used geostatistical modeling to map the distribution of size and activity of the denitrifier community in the pasture. Size of the denitrifier community was estimated by PCR quantification of the denitrification gene copy numbers while its activity was estimated by measurin…
Guinean and sahelian rainfall anomaly indices at annual and monthly scales (1933-1990)
1994
The annual and monthly rainfall variability in north tropical Africa are analysed by principal component analysis in order to detect the main coherent modes. The Sahel constitutes the first mode, although it is divided close to 1O"W into an Atlantic section and a Continental section. The Guinean zone is less coherent, and is divided into distinct modes. The subequatorial area never formed a distinct mode. Rainfall variability for the coherent areas is constructed from rainfall anomaly indices (RAI), based on the coherent areas, and a rainfall typology taking into account the spatial pattern of the rainfall anomaly fields and the intensity of the anomaly. Their evolution (mainly since 1950) …
Factors influencing spatial patterns of activity of denitrifying bacteria in a grassland soil
2008
International audience
Spatial patterns of microbial communities at a soil micro-scale
2012
International audience
Observations of land use transformations during the Neolithic using exploratory spatial data analysis: contributions and limitations
2010
International audience; The settlement pattern analysis in archaeology implies some methodological questions. In this paper, we question some issues about the use of geostatistical methods for the observation of land use transformations during the Neolithic. We have developed two examples in Burgundy (France): the first one on a regional scale and the second one on a micro-regional scale. Using different ESDA approaches (Ripley’K function, Nearest Neighbour Distance, Kernel Density Estimation), we would like to underline what the methodological and archaeological contributions and their limits are. Both experiences point out that the results obtained depend not only on the analytical scale,…
Firm Demography in the Accommodation Industry. Evidence from Italian Insular Regions
2020
The purpose of this study is to analyse the spatial pattern and the post-entry performance of tourism businesses in the Italian insular regions of Sardinia and Sicily. Using geo-referenced micro-data for the period 2011-2014, we explore the spatial distribution of ac-commodation firms in the two insular regions, and then compare the coastal and inland areas of the two regions. We observe a higher dispersion of firms in Sardinia than in Sicily; the latter, however having a higher concentration of firms in coastal and urban areas. We do not find significant differences in survival probability across the two insular regions but we do detect significant differences be-tween coastal and inland a…
Geostatistics for Mapping Leaf Area Index over a Cropland Landscape: Efficiency Sampling Assessment
2010
This paper evaluates the performance of spatial methods to estimate leaf area index (LAI) fields from ground-based measurements at high-spatial resolution over a cropland landscape. Three geostatistical model variants of the kriging technique, the ordinary kriging (OK), the collocated cokriging (CKC) and kriging with an external drift (KED) are used. The study focused on the influence of the spatial sampling protocol, auxiliary information, and spatial resolution in the estimates. The main advantage of these models lies in the possibility of considering the spatial dependence of the data and, in the case of the KED and CKC, the auxiliary information for each location used for prediction pur…
Seed dispersal, braeding system, tree density and the spatial pattern of trees – a simulation approach
2002
Summary Tropical tree populations with low densities and with clumped spatial distributions are at risk in the face of fragmentation. It is therefore important to understand factors driving spatial patterns of tree populations. An important set of factors which may influence the spatial pattern of plants, could be the spatial distribution of possible seed sources such as the breeding system (monoecious, dioecious), tree density and the spatial pattern of the parent population. Another set of important factors might be dispersal of seeds away from the parent plants characterised by the mean dispersal distance and by the distribution of dispersal distances (either negative exponential or logn…
Changes in spatial and sectoral patterns of employment in Ile-de-France, 1978-1997
2006
International audience; This paper investigates the spatial distribution of employment in the region of Ile-de-France in 1978 and 1997. Exploratory spatial data analysis is used to identify employment centres and a sectoral analysis of the central business district (CBD) and sub-centres is performed. The results highlight a process of suburbanisation of employment in Ile-de-France between 1978 and 1997. A more polarised space emerges in 1997 than in 1978, with several employment centres specialised in different activities. Moreover, even if the spatial influence of the CBD declines over the study period, the CBD maintains its economic leadership by concentrating a large variety of high-orde…