Search results for "Spatial ecology"

SPATIAL PATTERNS OF VOTING IN BUCHAREST AT THE EUROPEAN AND PRESIDENTIAL ELECTIONS OF 2019

2021

New insights into the neolithisation process in southwest Europe according to spatial density analysis from calibrated radiocarbon dates

2017

The agricultural way of life spreads throughout Europe via two main routes: the Danube corridor and the Mediterranean basin. Current archaeological literature describes the arrival to the Western Mediterranean as a rapid process which involves both demic and cultural models, and in this regard, the dispersal movement has been investigated using mathematical models, where the key factors are time and space. In this work, we have created a compilation of all available radiocarbon dates for the whole of Iberia, in order to draw a chronological series of maps to illustrate temporal and spatial patterns in the neolithisation process. The maps were prepared by calculating the calibrated 14C date …

Spatial Vote Redistribution in Redrawn Polling Units

2012

Summary A large proportion of electoral analyses using geography are performed on a small area basis. In each new election there are always modifications to the previously existing polling units. The use of past voting results in small area aggregate data electoral forecasting models and political analyses therefore requires establishing a correspondence between old and new polling units. Traditionally, the task of tracking changes to assign an electoral history to the new units properly has been carried out by hand, comparing unit codes and census figures. This is an extremely cumbersome task that cannot always be performed, as when a massive (geographically intense) reorganization of poll…

Inhomogeneity and complexity measures for spatial patterns

2002

In this work, we examine two different measures for inhomogeneity and complexity that are derived from non-extensive considerations à la Tsallis. Their performance is then tested on theoretically generated patterns. All measures are found to exhibit a most sensitive behaviour for Sierpinski carpets. The procedures here introduced provide us with new, powerful Tsallis’ tools for analysing the inhomogeneity and complexity of spatial patterns.

Role of the noise on the transient dynamics of an ecosystem of interacting species

2002

Abstract We analyze the transient dynamics of an ecosystem described by generalized Lotka–Volterra equations in the presence of a multiplicative noise and a random interaction parameter between the species. We consider specifically three cases: (i) two competing species, (ii) three interacting species (one predator–two preys), (iii) n-interacting species. The interaction parameter in case (i) is a stochastic process which obeys a stochastic differential equation. We find noise delayed extinction of one of two species, which is akin to the noise-enhanced stability phenomenon. Other two noise-induced effects found are temporal oscillations and spatial patterns of the two competing species. In…

Spatio-temporal patterns in population dynamics

2002

Abstract The transient dynamics of interacting biological species extracted from two ecosystems is investigated. We model the environment interaction by a multiplicative noise and the temperature oscillations by a periodic forcing. We find noise-induced effects such as enhanced temporal oscillations, spatial patterns and noise delayed extinction for the model of two competing species. We extend our analysis to an ecosystem of three interacting species, namely one predator and two preys. We find spatial patterns induced by the noise.

Spatio-temporal behaviour of the deep chlorophyll maximum in Mediterranean Sea: Development of a stochastic model for picophytoplankton dynamics

2013

In this paper, by using a stochastic reaction-diffusion-taxis model, we analyze the picophytoplankton dynamics in the basin of the Mediterranean Sea, characterized by poorly mixed waters. The model includes intraspecific competition of picophytoplankton for light and nutrients. The multiplicative noise sources present in the model account for random fluctuations of environmental variables. Phytoplankton distributions obtained from the model show a good agreement with experimental data sampled in two different sites of the Sicily Channel. The results could be extended to analyze data collected in different sites of the Mediterranean Sea and to devise predictive models for phytoplankton dynam…

Noise Induced Phenomena in the Dynamics of Two Competing Species

2015

Noise through its interaction with the nonlinearity of the living systems can give rise to counter-intuitive phenomena. In this paper we shortly review noise induced effects in different ecosystems, in which two populations compete for the same resources. We also present new results on spatial patterns of two populations, while modeling real distributions of anchovies and sardines. The transient dynamics of these ecosystems are analyzed through generalized Lotka-Volterra equations in the presence of multiplicative noise, which models the interaction between the species and the environment. We find noise induced phenomena such as quasi-deterministic oscillations, stochastic resonance, noise …

Spatio-Temporal Assessment of the European Hake (Merluccius merluccius) Recruits in the Northern Iberian Peninsula

2021

14 pages, 9 figures, 3 tables.-- This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY)

Groundwater biodiversity in Europe

2009

18 páginas, 7 figuras, 4 tables et al