Search results for " spatial pattern"

Causes and underlying processes of measurement variability in field erosion plots in Mediterranean conditions

2007

Published online 25 May 2006

Diel variability in counts of reef fishes and its implications for monitoring

2006

Studies of reef fish assemblages in space rarely consider the effects of temporal variability on spatial comparisons, and when they do, usually examine timescales of months to years. The nature of fish monitoring surveys is such that particular locations may be surveyed at one time of day, and surveys designed to establish the degree of spatial variability in assemblages may be confounded if the order of sampling within treatments is not randomised with respect to time of day. In this study, we tested the degree of temporal variability in temperate reef fish counts at the same sites in New Zealand and Italy, within and between days. Repeated counts separated by months returned quite differe…

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.

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…

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…

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…

Digital thermal monitoring of the Amazon forest: an intercomparison of satellite and reanalysis products

2015

Remote sensing and climate digital products have become increasingly available in recent years. Access to these products has favored a variety of Digital Earth studies, such as the analysis of the impact of global warming over different biomes. The study of the Amazon forest response to drought has recently received particular attention from the scientific community due to the occurrence of extreme droughts and anomalous warming over the last decade. This paper focuses on the differences observed between surface thermal anomalies obtained from remote sensing moderate resolution imaging spectroradiometer (MODIS) and climatic (ERA-Interim) monthly products over the Amazon forest. With a few e…

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…

Spatial pattern analysis of esca in different geographical areas of Italy.

2009

Detection of homogeneous precipitation regions at seasonal and annual time scales, northwest Iran

2017

Abstract Detection of homogeneous climate areas is a challenging issue, which can be affected by different criteria. One of the most prominent factors is choosing the time scale, which can lead to different spatial and temporal patterns. Total precipitation is a key factor in climatological studies, and studying its distribution is of utmost importance. The combination of principal components analysis and cluster analysis is used for homogeneous precipitation areas' detection. Hence, the spatial pattern of total precipitation was investigated in northwestern Iran during the past two decades (1991–2010) on seasonal and annual time scales. The results of clustering on each time scale were val…