Search results for "regression"

È possibile stimare le variazioni dei crediti di carbonio forniti dai suoli agricoli e forestali italiani

2011

L’Italia ha aderito al Protocollo di Kyoto, ma ha deciso di eleggere solo la gestione forestale nell’ambito delle attività addizionali previste per contabilizzare i crediti di carbonio. Lo scopo principale di questo lavoro è stato quello di dimostrare che è possibile stimare le variazioni del contenuto di carbonio organico dei suoli in Italia durante gli ultimi 3 decenni (dal 1979 al 2008) e contabilizzare i crediti di carbonio originati dalle attività di gestione sia agricola che forestale.

Past cover modulates the intense and spatially structured natural regeneration of woody vegetation in a pastureland

2020

Made available in DSpace on 2020-12-12T02:34:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-01 Università degli Studi di Palermo Ministero dell’Istruzione, dell’Università e della Ricerca Vegetation natural regeneration after agricultural abandonment is changing the landscape patterns in many areas worldwide. However, the expansion rate, spatio-temporal dynamics, and the role of past vegetation cover in shaping such patterns are still barely quantified in fine and meso scales. Here, we aim to quantify the expansion rate and assess the spatio-temporal patterns and the effects of past cover on natural woody vegetation cover increase. We sampled woodland and shrubland cover from …

Geospatial modelling and map analysis allowed measuring regression of the upper limit of Posidonia oceanica seagrass meadows under human pressure

2018

Abstract Marine coastal ecosystems are facing structural and functional changes due to the increasing human footprint worldwide, and the assessment of their long-term changes becomes particularly challenging. Measures of change can be done by comparing the observed ecosystem status to a purposely defined reference condition. In this paper, a geospatial modelling approach based on 2D mapping and morphodynamic data was used to predict the natural position of the upper limit (i.e., the landward continuous front) of Posidonia oceanica seagrass meadows settled on soft bottom. This predictive model, formerly developed at the regional spatial scale, was here applied for the first time at the Medit…

Life history traits to predict biogeographic species distributions in bivalves

2015

Organismal fecundity (F) and its relationship with body size (BS) are key factors in predicting species distribution under current and future scenarios of global change. A functional trait-based dynamic energy budget (FT-DEB) is proposed as a mechanistic approach to predict the variation of F and BS as function of environmental correlates using two marine bivalves as model species (Mytilus galloprovincialis and Brachidontes pharaonis). Validation proof of model skill (i.e., degree of correspondence between model predictions and field observations) and stationarity (i.e., ability of a model generated from data collected at one place/time to predict processes at another place/time) was provid…

Earth-flow susceptibility assessment in the Marvello River basin (Sicily, Italy)

2014

In this study, statistical models of earth-flow susceptibility were prepared using logistic regression. The analyses were carried out in a small (51 km2) basin of western Sicily, where 1,376 earth-flows were identified. To predict the spatial distribution of the mapped landslides, outcropping lithology and seven topographic attributes were exploited as explanatory variables. Before calculating these variables, a reconstruction of the pre-failure topography was performed. To evaluate the predictive skill and the robustness of the models, two groups made of five random subsets of earth-flows and stable cells were prepared. Absences of the first group were selected as individual cells whereas …

Landform classification: a high-performing mapping unit partitioning tool for landslide susceptibility assessment—a test in the Imera River basin (no…

2022

In landslide susceptibility studies, the type of mapping unit adopted affects the obtained models and maps in terms of accuracy, robustness, spatial resolution and geomorphological adequacy. To evaluate the optimal selection of these units, a test has been carried out in an important catchment of northern Sicily (the Imera River basin), where the spatial relationships between a set of predictors and an inventory of 1608 rotational/translational landslides were analysed using the multivariate adaptive regression splines (MARS) method. In particular, landslide susceptibility models were prepared and compared by adopting four different types of mapping units: the largely adopted grid cells (PX…

КАРТА ПОДВЕРЖЕННОСТИ ОПОЛЗНЕВОЙ ОПАСНОСТИ ТЕРРИТОРИИ РАЙОНОВ ШИЛАТО И КАЛЬТАВУТУРО (СЕВЕРНАЯ СИЦИЛИЯ). Logistic regression method for landslides susc…

2012

The studied area is located within two Sicilian districts– Scillato and Caltavuturo. Studied area is 200 km2. This territory is affected by large landslides very strongly. In the course of the research these districts were divided into 2 million square units of 10 × 10 m. Values of landslide factors were assessed within each unit. Using method of logistic regression allowed us to select the most significant factors and to make the landslide susceptibility map. Landslide hazard analys was made with 3 models, which analyze different diagnostic areas (places, where landslides are trigger usually). The results indicate that the using of the buffer zone with radius 50 m around the highest point …

Comparing Logistic Regression and MARS approaches for gully erosion susceptibility evaluation in central-northern Sicily

2012

STATISTICAL MODELS FOR LANDSLIDE SUSCEPTIBILITY ASSESSMENT: METHODOLOGICAL ISSUES AND GUIDELINES FOR MEDITERRANEAN CONTEXT

2012

La población mundial, que cuenta dos mil millones de habitantes alrededor del año 1950, ha crecido a un ritmo casi exponencial en las décadas siguientes hasta 4 mil millones y 5,3 en 1990 (Naciones Unidas - Departamento de Asuntos Económicos y Sociales, 2010). Sin duda un gran aumento tanto en términos absolutos cuanto relativos. Según las estimaciones de las Naciones Unidas, la población mundial se estima que alcanzará los ocho millones y medio de 2025. Estas tasas de crecimiento se producen, obviamente, tanto en Europa, donde la población ha crecido de 550 millones en 1950 a 750 millones en 2010, y en Italia, donde en el período 1861 a 2008 hubo un aumento de la población de 22 millones d…

The geo-hydrologic event in the Peloritan – Ionian area of 2009: debris-flow susceptibility assessment by means of forward logistic regression

2012

On the 1st of October 2009, the area centred on the village of Giampilieri (Messina), on the Ionian side of the Peloritan belt, suffered thousands of landslides activated in the time lapse of about five hours, which caused 36 victims, more than 100 injured and more than 0.5M€ of damage to structures. This unprecedented phenomenon was triggered by an exceptional meteorological event, recorded at the foothills with 250mm of rain in just 8 hours; this amount of rainfall was cumulated to two previous events (16/IX: 75mm; 23/IX: 190mm) for a total amount of more than 500mm in less than two weeks. Due to the peculiar triggering conditions a huge number of debris flows involved the shallow weather…