Summary: Drought‐induced tree mortality frequently occurs in patches with different spatial and temporal distributions, which is only partly explained by inter‐ and intraspecific variation in drought tolerance. We investigated whether bedrock properties, with special reference to rock water storage capacity, affects tree water status and drought response in a rock‐dominated landscape. We measured primary porosity and available water content of breccia (B) and dolostone (D) rocks. Saplings ofFraxinus ornuswere grown in pots filled with soil or soil mixed with B and D rocks, and subjected to an experimental drought. Finally, we measured seasonal changes in water status of trees in field sites overlying B or D bedrock. B rocks were more porous and stored more available water than D rocks. Potted saplings grown with D rocks had less biomass and suffered more severe water stress than those with B rocks. Trees in sites with B bedrock had more favourable water status than those on D bedrock which also suffered drought‐induced canopy dieback. Bedrock represents an important water source for plants under drought. Different bedrock features translate into contrasting below‐ground water availability, leading to landscape‐level heterogeneity of the impact of drought on tree water status and dieback.

Increased frequency of tree mortality and forest decline due to anomalous drought events calls for the adoption of effective monitoring of tree water status over large spatial and temporal scales. We correlated field-measured and remotely sensed plant water status parameters, to test the possibility of monitoring the risk of drought-induced dehydration and hydraulic failure using satellite images calibrated on reliable physiological indicators of tree hydraulics. The study was conducted during summer 2019 in the Karst plateau (NE Italy) in a woodland dominated by Fraxinus ornus L.; Sentinel-2 images were acquired on a seasonal scale on the same dates when absolute water content (AbWC), relative water content (RWC), and minimum water potential (Ψ_min) were measured in the field. Plant water status parameters were correlated with normalized difference vegetation index (NDVI and NDVI 8A), normalized difference water index (NDWI), and soil-adjusted vegetation index (SAVI). Significant Pearson and Spearman linear correlations (α < 0.05) emerged between all tree-level measured variables and NDWI, while for NDVI, NDVI 8A, and SAVI no correlation was found. Our results suggest the possibility of using the NDWI as a proxy of tree water content and water potential.

Invasion by alien plant species may be rapid and aggressive, causing erosion of local biodiversity. This is particularly true for islands, where natural and anthropogenic corridors promote the rapid spread of invasive plants. Although evidence shows that corridors may facilitate plant invasions, the question of how their importance in the spread of alien species varies along environmental gradients deserves more attention. Here, we addressed this issue by examining diversity patterns (species richness of endemic, native and alien species) along and across roads, along an elevation gradient from sea-level up to 2050 m a.s.l. in Tenerife (Canary Islands, Spain), at multiple spatial scales. Species richness was assessed using a multi-scale sampling design consisting of 59 T-transects of 150 m × 2 m, along three major roads each placed over the whole elevation gradient. Each transect was composed of three sections of five plots each: Section 1 was located on the road edges, Section 2 at intermediate distance,...

This study was carried out using Ixodes ricinus ticks collected during 2005 and 2006 from the Friuli Venezia Giulia (FVG) region in the northeastern part of Italy and an area along the Slovenian side of the western border of Italy. The results indicate that Rickettsia spp. is widely distributed throughout these areas, with the greatest prevalence in the central part of the FVG region. The prevalence of Rickettsia spp. was 4.5% during 2005 and 6.1% during 2006. By sequencing the 16S rRNA gene, we show for the first time the presence of Rickettsia helvetica in I. ricinus ticks in the FVG region and the presence of R. monacensis in ticks in both areas. Furthermore, we detected a sequence with a high homology with that of R. limoniae in a tick obtained from the alpine zone.