A Vegetation Indicator To Assess Mediterranean Pinewood Affected By Bast Scale (Matsucoccus FeytaudiI)

The bast scale (Matsucoccus feytaudi) is responsible for the destruction of most of the Pinus pinaster forests in the Mediterranean area, causing resination, defoliation and subsequent death of the tree. Questions: is it possible to estimate pinewood health by analysing understory vegetation? Does the health status of pine forests changes during time? Do such variations involve understorey vegetation? What species in the understory vegetation better describe different conditions? What are the most relevant variables (defoliation and resination) influencing pine stands' condition. Location: The study area is located in the eastern part of Liguria (Italy) in pinewood affected by the bast scale Matsucoccus feytaudi. Method: we used: (1) hierarchical cluster analysis to discriminate pinewood health conditions (good and bad); (2) non-metric multidimensional scaling (NMS) to detect the most important variables influencing the pine stands' condition and understory vegetation; and (3) indicator species analysis (ISA) to determine indicator species corresponding to health conditions at the plot level. Our aim was to find a relationship between pines' health status and the variation in pinewood understory vegetation communities. Results: we found that understory vegetation composition depends on both pine stand health status and environment-related factors. Geographic variables (in particular latitude and altitude) and tree-related variables (percentage of resinated and defoliated trees) were associated with the main axes of variability of the understory vegetation. Three indicator species (Erica arborea, Quercus ilex and Castanea sativa), which were closely linked to pine stands health status, were significantly associated with different stages of pinewood dieback caused by bast scale. Conclusion: this study provides useful information and a good operational tool for technicians working in the forestry sector, and for public administrations and land managers to start good land-use planning

Flow Characterization of a Pulsating Heat Pipe through the Wavelet Analysis of Pressure Signals

Pulsating Heat Pipes are two phase passive heat transfer devices characterized by a thermally induced two phase oscillating flow. The correct detection of the dominant frequencies of such oscillations is fundamental to fully characterize the device thermofluidic operation but the studies available in the literature are very heterogenous and results are often discordant. In this work, the concept of dominant frequency in Pulsating Heat Pipes is thoroughly discussed and defined analytically. The wavelet transform is used to characterize the fluid pressure signal in the frequency domain varying the heat power input at the evaporator and in the condenser zone of a full-scale Pulsating Heat Pipe tested in microgravity conditions. During the slug-plug flow regime, the dominant frequencies falls in the range 0.6–0.9 Hz, showing an increasing trend with the heat load input. The Cross-Correlation reveals that the two signals at the evaporator and at the condenser are very similar. Finally, the instantaneous angle of phase is calculated and lies between 310 and 360 deg. This value can be physically interpreted as a repeatable time shift between the two signals that can be used to evaluate the flow local mean velocity (0.09–0.13 m/s) constituting a valuable alternative to the visualization techniques

Volumetric expression of palynological spectra for nutritional studies

When pollen is studied from nutritional point of view, it would be desirable to correct its raw palynological spectrum in order to express the mass contribution of each pollen type. Different approaches applied for this correction through volumetric coefficients are discussed, and a simple and reliable procedure is proposed

Sulfide weathering processes mediated by microfungi

This study aimed to experimentally investigate the interactions, the bioalteration, and the biocorrosion of sulfides mediated by three microfungi (Trichoderma harzianum group, Penicillium glandicola, P. brevicompactum) isolated within the open-air waste-rock dumps from Libiola mine (Liguria, Italy). Unaltered samples of pyrite-mineralizations from the same waste-rock dumps were ground and sieved into size fraction of 150-63 \u3bc m which resulted composed by single crystals of pyrite (>80 wt%), with minor quartz and trace amount of chalcopyrite. The mineral bioalteration tests were carried out for six weeks using Czapek-Dox agar medium (CZA). In each plate, four pyrite crystals or crystal fragments were set into the solid medium. After one week, pyrite grains were almost completely covered by mycelia of the three different fungi. The samples were examined, before and after the experimental procedure, using plane-polarized optical microscopy (transmitted- and reflected-light) and environmental scanning electron microscopy (ESEM-EDS). The ESEM analyses were performed in low-vacuum mode for the micromorphological analyses to characterize the evolution of the mineralfungi interactions during the different experimental steps. After six weeks covered by mycelia, the pyrite grains were collected and analyzed revealing that the surface of pyrite crystals was strongly corroded in all experimental tests. ESEM images underlined how pyrite alteration was strictlty associated with biological patterns (curves, rounded cracks, and sinuous traces). Corrosion patterns and etching pits were not related to specific crystallographic planes or weakness, but were randomly distributed on the crystal surfaces, in particular in correspondence of the fungal hyphae attachment. Moreover, in the same temporal interval, the control experiment performed in abiotic conditions did not show any dissolution evidences thus suggesting that in absence of fungal interactions the pyrite weathering did not occur or was much slower. The experimental results evidenced the active role of fungi in the pyrite crystal weathering and suggested that sulfide alteration was not only the consequence of the interactions between metabolites secreted by fungi and minerals, but there was also a possible bio-mechanical role of hyphae in corrosion through penetration, boring, and burrowing along weak crystal planes or microfractures. Finally, the evidences of biocorrosion led to evaluate the important role of fungi in the iron and sulfur cycles in sulfide-bearing materials, since fungal alteration systematically triggers sulfide to sulfate oxidation, causing local gypsum and Fe-oxyhydroxides precipitation within mycelium structure