Carlotta Ferrara

In-between sprawl and fires: long-term forest expansion and settlement dynamics at the wildland–urban interface in Rome, Italy

Understanding the intimate dynamics of urban–wildland interfaces in Mediterranean landscapes is particularly challenging because of multiple biophysical factors (dry or arid climate, low-quality soils, poor vegetation cover) determining an increased environmental sensitivity to human pressure. Although dense and compact cities were sprawling rapidly in the most recent decades, many suburban areas in southern Europe still preserve biodiversity-rich habitats, traditional crop mosaics and high-quality relict forest stands. Diachronic forest and settlement maps were analysed over two time intervals (1936–1974 and 1974–2006) representing different socio-economic contexts on a local scale with the aim to assess trends in forest land cover vis à vis urban growth in Rome, central Italy. Forests expanded into agricultural land during the whole time period following cropland abandonment and benefiting from a higher level of land protection from urbanisation, especially during the most recent decades. Although the broadleaved wood dominated the composition of forest fragments at the wildland–urban interface at both the beginning and the end of the study period, coniferous stands showed a slower decrease compared to other wood types, such as those dominated by chestnut or beech. The observed changes in forest composition are the result of a higher disturbance level, possibly triggered by the increase of fire frequency and severity, a higher fragmentation of natural land, intense soil sealing and a larger occurrence of invasive species. Forest diversity increased especially in areas with medium-density settlements, indicating a tendency towards more heterogeneous forest structures at the urban–wildland interface compared to natural landscapes. A long-term monitoring of settlement dynamics and woodland expansion is required to inform a sustainable management of Mediterranean suburban forests.

Comparison of GPR and unilateral NMR for water content measurements in a laboratory scale experiment

Several factors affect antenna-soil coupling in a Ground Penetrating Radar (GPR) survey, like surface roughness, lithology, lateral heterogeneities, vegetation, antenna height from the surface and water content. Among them, lithology and water content have a direct effect on the bulk electromagnetic properties of the material under investigation. It has been recently pointed out that the wavelet of the early-time portion of a radar signal is correlated to the shallow subsurface dielectric properties of a material. This result indicates that some information on such properties can be directly extracted from the analysis of GPR early-time traces. In the present paper, we use the early-time GPR signal, in terms of average envelope amplitude computed on the first half-cycle, to map the near-surface (few centimetres) lateral distribution of dielectric parameters, induced by changing the shallow water content on a concrete slab. This controlled experiment was specifically designed to study the effect of water content variations on antenna-material coupling, minimizing the influence of both surface roughness and heterogeneity. The quantitative control of the water in the shallow portion of the slab is performed by using a portable unilateral Nuclear Magnetic Resonance (NMR) sensor, which is able to determine the water content in the material on the basis of the measured proton density. The results show a matching pattern of the physical parameters measured with the two different techniques and a very high degree of linear correlation (r = 0.97) between the radar early-time signal average amplitude and the intensity of the NMR signal, which is proportional to the proton density, i.e., to the water content. This experiment suggests that the early-time approach could be used as a fast and high- spatial resolution tool for qualitatively mapping water content lateral variations in a porous material at shallow depth, using a ground-coupled single-offset antenna configuration and that a quantitative evaluation of the moisture content would require a calibration procedure.

Toward sustainable forest management indicators? A data mining approach to evaluate the impact of silvicultural practices on stand structure

ABSTRACT Indicators are increasingly required to support a fine-tuning between sustainable forestry and multiple environmental targets. A data mining strategy was implemented in this study to assess the overall impact of traditional and innovative silviculture on stand structure in a sample of beech forests with varying dominant age, management history and stand structure in Italy. Harvesting intensity and stand sensitivity to treatment were investigated using a principal component analysis (PCA) run on a set of dendrometric and stand-structure variables measured before and after practice implementation at the scale of forest compartment. The PCA decomposed the overall impact of silviculture on forest structure in two manipulative effects: (i) structural changes between control and treatments, and (ii) the net manipulative effect of innovative versus traditional treatment. Our approach informs the sustainable management of forests, outlining between-site differences in stand structure and identifying a diversity gradient shaped by silvicultural practices. Multivariate analysis of forest indicators following practice’s implementation is a promising tool to design innovative silviculture coherent with conservation of forests’ structural diversity.

An evaluation of the early-time GPR amplitude technique for electrical conductivity monitoring

In the present paper we use the recently-proposed early-time GPR (Ground Penetrating Radar) amplitude technique with the aim of detecting the variations of electric conductivity in a porous material having a uniform permittivity. A specific laboratory setup has been realised to evaluate the sensitivity of the early-time amplitudes to the variations of the subsurface salt concentration (i.e., conductivity). To assess the capacity of the early-time amplitude to follow the electrical conductivity changes, we compare the early-time results acquired using the envelope of the first part of GPR signals with the concurrent conductivity measured with TDR (Time Domain Reflectometry). The GPR survey has been carried out using a bistatic radar unit (Sensors & Software, Inc) operating at 1 GHz. Further useful information has been derived by suitably implementing a full-wave numerical modelling, able to accurately analyse the features of the waves detected by the GPR with flexible parameterization. Our results indicate that the near-surface electromagnetic properties of the material can be directly extracted from the GPR early-time amplitude technique. In particular, both experimental and numerical data show a very high correlation coefficient between the radar signal amplitude and the TDR-derived electrical conductivities.

Opening the frontier:The Gubbio-Perugia frontier in the course of history

The frontier between Gubbio (ancient Umbria) and Perugia (ancient Etruria), in the northeast part of the modern region of Umbria, was founded in the late sixth century bc. The frontier endured in different forms, most notably in the late antique and medieval periods, as well as fleetingly in 1944, and is fossilized today in the local government boundaries. Archaeological, documentary and philological evidence are brought together to investigate different scales of time that vary from millennia to single days in the representation of a frontier that captured a watershed of geological origins. The foundation of the frontier appears to have been a product of the active agency of the Etruscans, who projected new settlements across the Tiber in the course of the sixth century bc, protected at the outer limit of their territory by the naturally defended farmstead of Col di Marzo. The immediate environs of the ancient abbey of Montelabate have been studied intensively by targeted, systematic and geophysical survey in conjunction with excavation, work that is still in progress. An overview of the development of the frontier is presented here, employing the data currently available.

Forensic Geophysics: how GPR could help police investigations

Police regularly use GPR to uncover buried caches of drugs, money, weapons as well as locate unmarked graves. GPRs versatility and sensitivity to buried objects has lead to an ever widening use in forensics. While GPR does not deliver the fantasy results portrayed on some TV shows, GPR can provide powerful insight to forensics specialists needing to conduct non-destructively detailed subsurface site investigations.

Not necessarily buried bodies: Forensic GPR investigations from criminal to civil justice

Normally, when the GPR (ground penetrating radar) method is involved in forensic investigations, it is to search for missing bodies, generally buried under the ground. In the literature, it is possible to find several studies and examples to this effect. Recently, this technique has become relevant not only in criminal but also civil justice. Numerous civil cases, in which geophysical approaches have been used, particularly GPR, have become as important as the criminal cases, particularly in Italy. One of these cases involves the Ministry of Cultural Heritage and its power to put a legal restriction on an area with high archaeological potential. Based on this, nobody, including the landowners, can remove soil for any purpose, including building new construction and planting. The cases in which the GPR technique is involved in the research of pollutants or illegal dumping underneath the soil surface are also frequent. The chemical and physical modification of the soil both in the shallow and in the deep part of the subsurface creates the perfect dielectric contrast that is detectable by the GPR system. This paper will show the various ways in which forensic GPR investigations can help in criminal and civil justice at the same level of high standards and with the same distinguished results.

Exploring the multiplicity of soil–human interactions: organic carbon content, agro-forest landscapes and the Italian local communities

Topsoil organic carbon (TOC) and soil organic carbon (SOC) are fundamental in the carbon cycle influencing soil functions and attributes. Many factors have effects on soil carbon content such as climate, parent material, land topography and the human action including agriculture, which sometimes caused a severe loss in soil carbon content. This has resulted in a significant differentiation in TOC or SOC at the continental scale due to the different territorial and socioeconomic conditions. The present study proposes an exploratory data analysis assessing the relationship between the spatial distribution of soil organic carbon and selected socioeconomic attributes at the local scale in Italy with the aim to provide differentiated responses for a more sustainable use of land. A strengths, weaknesses, opportunities and threats (SWOT) analysis contributed to understand the effectiveness of local communities responses for an adequate comprehension of the role of soil as carbon sink.

An objective image analysis method for estimation of canopy attributes from digital cover photography

Key messageA method was proposed to remove the subjectivity of gap size analyses approaches implemented by default in cover photography. The method yielded robust and replicable measurements of forest canopy attributes.AbstractDigital cover photography (DCP) is an increasingly popular method to estimate canopy attributes of forest canopies. Compared with other canopy photographic methods, DCP is fast, simple, and less sensitive to image acquisition and processing. However, the image processing steps used by default in DCP have a large substantial subjective component, particularly regarding the separation of canopy gaps into large gaps and small gaps. In this study, we proposed an objective procedure to analyse DCP based on the statistical distribution of gaps occurring in any image. The new method was tested in 11 deciduous forest stands in central Italy, with different tree composition, stand density, and structure, which is representative of the natural variation of these forest types. Results indicated that the new method removed the subjectivity of manual and semi-automated gap size classifications performed so far in cover photography. A comparison with direct LAI measurements demonstrated that the new method outperformed the previous approaches and increased the precision of LAI estimates. Results have important implications in forestry, because the simplicity of the method allowed objective, reliable, and highly reproducible estimates of canopy attributes, which are largely suitable in forest monitoring, where measures are routinely repeated. In addition, the use of a restricted field of view enables implementation of this photographic method in many devices, including smartphones, downward-looking cameras, and unmanned aerial vehicles.

Ground-Penetrating Radar technique to investigate historic eruptions on the Mt. Etna volcano (Sicily, Italy)

In the present paper we demonstrate the capability of different remote sensing techniques to reconstruct the evolutionary history of the lava flows on the Mt. Etna volcano. A preliminary approach to the sites, based on aerial photogrammetry, DEM, and topographic analyses, supports an intense GPR (Ground Penetrating Radar) survey in several sites with different stratigraphical characteristics. The GPR measurements are performed with a bistatic system equipped with both 500 and 1000 MHz antennas. The use of different polarizations (TE, TM, Cross-Tx, and Cross-Rx) allow to extract subsurface features information having 3D geological structure reconstruction, electromagnetic nature information and properties of buried reflectors. This preliminary study highlights how the GPR technique provides, non-destructively, useful data to study the mechanisms of emplacement and the correlated hazard. Furthermore, if an inactive lava tubes can only be detected after the collapse of their vault, the use of GPR, on the contrary, could help to locate buried undamaged lava tubes and to measure their dimensions, providing useful structural information. Lava tubes, also, strongly influences the development of lava fields and the hazard connected with them, because they keep the lava thermally isolated causing a propagation longer than it would have done in an open channel. Additionally, the combined use of different remote sensing techniques can be useful to better estimate the thickness of the lava fields, giving precious data about the nature of the flow. Finally, the results highlight the importance of this combined approach to evaluate different physical parameters at the same time.