Search results for "Spatial heterogeneity"

Residence Time Analysis in the Albufera of Valencia, a Mediterranean Coastal Lagoon, Spain

2021

The Albufera of Valencia is a coastal lagoon located in the western area of the Mediterranean Sea, in the Iberian Peninsula. It has an area of 23.1 km2 and an average depth of only 1 m, with a maximum depth of 1.6 m. This lagoon is the remnants of an original and more extensive wetland of about 220 km2 which is now mostly dedicated to rice cultivation. Surface water is supplied through several main and many secondary canals for a total of 64 water entry points and three exit points to the sea. It is difficult to evaluate the residence time due to the lack of reliable measurements of the inflow or outflow, as well as continuous measurements. Between 1988 and 2018, several procedures were use…

High-to-low (Regional) fertility transitions in a peripheral european country: The contribution of exploratory time series analysis

2021

Diachronic variations in demographic rates have frequently reflected social transformations and a (more or less evident) impact of sequential economic downturns. By assessing changes over time in Total Fertility Rate (TFR) at the regional scale in Italy, our study investigates the long-term transition (1952–2019) characteristic of Mediterranean fertility, showing a continuous decline of births since the late 1970s and marked disparities between high- and low-fertility regions along the latitude gradient. Together with a rapid decline in the country TFR, the spatiotemporal evolution of regional fertility in Italy—illustrated through an exploratory time series statistical approach—outlines th…

Food plant diversity as broad-scale determinant of avian frugivore richness.

2007

The causes of variation in animal species richness at large spatial scales are intensively debated. Here, we examine whether the diversity of food plants, contemporary climate and energy, or habitat heterogeneity determine species richness patterns of avian frugivores across sub-Saharan Africa. Path models indicate that species richness of Ficus (their fruits being one of the major food resources for frugivores in the tropics) has the strongest direct effect on richness of avian frugivores, whereas the influences of variables related to water–energy and habitat heterogeneity are mainly indirect. The importance of Ficus richness for richness of avian frugivores diminishes with decreasing sp…

215P Analysis of spatial heterogeneity of responses in metastatic sites with nivolumab in renal cell carcinoma

2020

Equilibrium/steady-state concept in phytoplankton ecology

2003

This paper summarises the outcomes of the 13th Workshop of the International Association of Phytoplankton Taxonomy and Ecology (IAP). The authors mostly addressed their contributions on the following topics: the effect of trophic state on the attainment of a steady-state; the establishment of equilibria in deep and shallow lakes; the role of spatial heterogeneity, disturbance, and stress in the establishment of equilibrium assemblages; the mechanisms leading to the steady state; the frequency and longevity of equilibrium phases, and the role of morphological and physiological plasticity of phytoplankton in maintaining the (apparently) same populations under different environmental condition…

Analyse spatiale des disparités régionales dans l'Europe élargie

2004

The aim of this paper is to study the regional inequalities in the enlarged European Union using Exploratory Spatial Data Analysis applied to per capita GDP for 258 regions of EU27 over the period 1995-2000. Strong evidence in favor of global and local autocorrelation as well as spatial heterogeneity is found for the wealth distribution. We also show that the enlargement process leads to a new North-West - East polarization scheme instead of the previous results obtained in the literature highlighting a North-South polarization scheme. Implications for regional development and cohesion policies are finally explored.

Determinants of macroinvertebrate diversity in headwater streams: regional and local influences

2003

Summary 1 Multiscale determinants of diversity and the relationship between regional (RSR) and local richness (LSR) have recently attracted increased attention, yet such studies on stream organisms remain scarce. We studied the relationships among RSR, β-diversity, LSR and local environmental variables in 120 headwater streams in Finland. Approximately similar-sized areas of eight drainage systems were defined as regions, and 15 stream riffles (= locality) per region were sampled. 2 RSR showed a strong positive relationship with mean LSR (R2 = 0·686), and there was no sign of curvilinearity within the observed range of RSR. RSR was also positively, although non-significantly, related to β-d…

Trophic adaptability shapes isotopic niche of the resident fish Aphanius fasciatus across lagoon habitats

2022

Abstract Coastal lagoons are characterized by high habitat heterogeneity where natural habitats coexist with artificial ones, historically set up to support human activities. Increasing anthropogenic pressure may lead to progressive degradation of the most vulnerable lagoonal habitats and the associated biological communities. One of the strictly estuarine-dependent fish species that may be affected by the degradation of lagoon habitats is the South European toothcarp Aphanius fasciatus, archetype of Mediterranean lagoon residents. Carbon and nitrogen stable isotopes were used to disentangle the influence of habitat types (natural vs artificial) and fish community (multi-trophic context) on…

Trophic and spatial complementarity on seed dispersal services by birds, wild mammals, and cattle in a Mediterranean woodland pasture

2021

Made available in DSpace on 2022-05-01T09:47:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Università degli Studi di Palermo CYTED Ciencia y Tecnología para el Desarrollo Federación Española de Enfermedades Raras Most earth surfaces have undergone intensive land-use changes, creating habitat mosaics. Seed dispersal by animals is a crucial process in such mosaics, but community-wide studies comparing the functional complementarity and response to man-imposed habitat heterogeneity are rare. Here, we investigate the trophic and spatial seed dispersal networks underpinning a strong, woody vegetation expansion over a pastureland inside the largest forest remnant in western Sici…

Contrasting age-specific recruitment and survival at different spatial scales: A case study with the European storm petrel

2009

Evolutionary studies on optimal decisions or conservation guidelines are often derived by generalising patterns from a single population, while inter-population variability in life-history traits is seldom considered. We investigated here how survival and recruitment probabilities changed with age at different geographical scales using the encounter histories of 5523 European storm petrels from three Mediterranean colonies, and also how our estimates of these parameters might be expected to affect population growth rates using population matrix models. We recorded similar patterns among colonies, but also important biological differences. Local survival, recruitment and breeding success inc…