Search results for " spatial pattern"
showing 10 items of 39 documents
The advantage of alternative tactics of prey and predators depends on the spatial pattern of prey and social interactions among predators
2011
Individual variation in behavioral strategies is ubiquitous in nature. Yet, explaining how this variation is being maintained remains a challenging task. We use a spatially-explicit individual-based simulation model to evaluate the extent to which the efficiency of an alternative spacing tactic of prey and an alternative search tactic of predators are influenced by the spatial pattern of prey, social interactions among predators (i.e., interference and information sharing) and predator density. In response to predation risk, prey individuals can either spread out or aggregate. We demonstrate that if prey is extremely clumped, spreading out may help when predators share information regarding…
Spatial pattern analysis using hybrid models: an application to the Hellenic seismicity
2016
Earthquakes are one of the most destructive natural disasters and the spatial distribution of their epi- centres generally shows diverse interaction structures at different spatial scales. In this paper, we use a multi-scale point pattern model to describe the main seismicity in the Hellenic area over the last 10 years. We analyze the interaction between events and the relationship with geo- logical information of the study area, using hybrid models as proposed by Baddeley et al. ( 2013 ). In our analysis, we find two competing suitable hybrid models, one with a full parametric structure and the other one based on nonpara- metric kernel estimators for the spatial inhomogeneity.
Plant colonization of a bare peat surface: population changes and spatial patterns
1992
. Changes in size and spatial arrangement of plant populations established on an initially bare peat surface were described over a period of 5 yr by following plant individuals on a 1-cm grid in an area of 10 m x 25 m. The spatial pattern of populations and association between species was analyzed statistically. The study site was very slowly colonized by 14 perennial plant species. The early successional stage was dominated by Carex rostrata, with a clumped spatial distribution, and the homogeneously distributed Eriophorum vaginatum and Pinus sylvestris. Both the growth in size of populations and changes in their spatial distribution were interpreted as a result of species dispersal abilit…
Exploratory spatial data analysis of the distribution of regional per capita GDP in Europe, 1980-1995
2000
The aim of this paper is to study the dynamics of European regional per capita product over time and space. This purpose is achieved by using the recently developed methods of Exploratory Spatial Data Analysis. Using a sample of European regions over the 1980-1995 period, we find strong evidence of global and local spatial autocorrelation in per capita GDP throughout the period. The detection of clusters of high and low per capita products during the period is an indication of the persistence of spatial disparities between European regions. This analysis is finally refined by the investigation of the spatial pattern of regional growth. Key words:exploratory spatial data analysis; distributi…
The influence of geography on the spatial agglomeration of production in the European Union
2012
Abstract We investigate the relative impact of geographic features on the location of production in the European Union. Specifically, we attempt to quantify how much of the spatial pattern of GDP can be attributed to exogenous first-nature elements alone and how much can be derived from endogenous second-nature factors. In order to disentangle both effects empirically, we control for second-nature factors. A method based on the decomposition of the per capita GDP variance is applied to a panel of 1,171 European NUTS 3 regions for 2006. We demonstrate that variable and model misspecifications may bias results unless proper allowance is made for spatial autocorrelation and spatial heterogenei…
Analysis of soil surface component patterns affecting runoff generation. An example of methods applied to Mediterranean hillslopes in Alicante (Spain)
2008
Spatial patterns of soil surface components (vegetation, rock fragments, crusts, bedrock outcrops, etc.) are a key factor determining hydrological functioning of hillslopes. A methodological approach to analyse the patterns of soil surface components at a detailed scale is proposed in this paper. The methods proposed are applied to two contrasting semi-arid Mediterranean hillslopes, and the influence of soil surface component patterns on the runoff response of the slopes was analysed. A soil surface components map was derived from a high resolution photo-mosaic obtained in the field by means of a digital camera. Rainfall simulation experimental data were used to characterise the hydrologica…
A Framework to Assess the Information Dynamics of Source EEG Activity and Its Application to Epileptic Brain Networks
2020
This study introduces a framework for the information-theoretic analysis of brain functional connectivity performed at the level of electroencephalogram (EEG) sources. The framework combines the use of common spatial patterns to select the EEG components which maximize the variance between two experimental conditions, simultaneous implementation of vector autoregressive modeling (VAR) with independent component analysis to describe the joint source dynamics and their projection to the scalp, and computation of information dynamics measures (information storage, information transfer, statistically significant network links) from the source VAR parameters. The proposed framework was tested on…
The Evolution of Territorial Occupation:
2012
International audience; The analysis of territorial changes over time raises many methodological questions. Despite a very frequent use of spatial analysis methods, few works underline their methodological shortcomings. This paper considers a comparison and discussion of exploratory statistical methods (notably Ripley's K function and its derivatives). It is worth noting three parameters in archaeological spatial analysis: scale, quality and quantity of input data. Archaeological data are intrinsically heterogeneous. Therefore, our approach proposes a multiscalar process integrating heterogeneous data. We describe a range of methods for the description and analysis of heterogeneous spatial …
Mapping Ash CaCO3, pH, and Extractable Elements Using Principal Component Analysis
2017
Abstract Ash cover in fire-affected areas is an important factor in the reduction of soil erosion and increased availability of soil nutrients. Thus it is important to understand the spatial distribution of ash and its capacity for soil protection and to provide nutrients to the underlying soil. In this work, we aimed to map ash CaCO3, pH, and select extractable elements using a principal component analysis (PCA). Four days after a medium to severe wildfire, we established a grid in a 9 ×27 m area on a west facing slope and took ash samples every 3 m for a total of 40 sampling points. The PCA carried out retained five different factors. Factor 1 had high positive loadings for ash with elect…
Causes and underlying processes of measurement variability in field erosion plots in Mediterranean conditions
2007
Published online 25 May 2006