Compacted soils in urban areas suffer from reduced porosity, impairing plant growth, water infiltration, and gas exchange, thus exacerbating other potential environmental issues. Amending soil with organic matter can reduce bulk density and increase permeability, thereby enhancing soil fertility and functionality. This study evaluated the effects of two organic soil amendments (i.e., chipped cork and municipal waste compost) on soil functionality and the physiology of Quercus ilex trees, following a soil compaction treatment. Five soil treatments were compared: control (no compaction and amendments), soil compaction without amendments, and compaction with amendments including cork, compost, or a combination of both. Soil and plant physiological responses were analyzed during the summer months, focusing on soil gas exchange, temperature, moisture, microbial respiration, enzymatic activity, leaf gas exchange, leaf chlorophyll fluorescence, chlorophyll content, and maximum daily trunk shrinkage. The results showed that amended soils exhibited increased soil gas exchanges, lower temperatures, and higher microbial activity than non-amended compacted soils, thereby reducing the detrimental effects of soil compaction on plant physiology. These findings suggested that incorporating organic amendments into urban soils, especially those subjected to frequent trampling, could make them more resistant/resilient to compaction, supporting healthier green spaces and more sustainable urban ecosystems.

Climate change is increasingly exposing sweet chestnut (Castanea sativa Mill.) to more frequent and prolonged drought events, which can compromise growth and nut production, particularly in Mediterranean environments. Understanding how trees respond physiologically to ecological and environmental constraints requires a detailed analysis of their architectures. The aim of this study was to investigate how the shoot vigour and leaf water status of mature chestnut trees vary with height within the canopy. Three mature chestnut trees with distinct crown architectures were selected in a traditional chestnut orchard in Central Italy; the differences in crown structure reflected individual tree development under comparable pruning practices. Morphological traits, leaf water status, and physiological parameters related to chlorophyll were measured directly within the canopy by professional tree climbers, allowing access to both lower and upper shoots during the growing season of 2020. One tree, called “Tree 1,” characterised by low bifurcation, with all epicormic shoot cluster (complexes) located on the two main branches and none on the main stem, showed partial vertical differences, mainly in water status and chlorophyll traits. “Tree 2”, characterised by high bifurcation and shoots running along the main stem, exhibited clear vertical gradients: lower-canopy shoots had larger leaf areas and more dry mass, higher relative water content, and better photosynthetic performance index e values than upper shoots. At the end, “Tree 3”, with the same architecture as Tree 1, displayed no consistent vertical trends. These findings indicate that individual tree architecture modulates hydraulic constraints and shoot vigour, even in hydraulically efficient epicormic branches. Although canopy access constraints limited the number of trees and measurements, this study—among the few to conduct in-canopy measurements on large, mature trees—provides valuable guidance for pruning and crown management, suggesting that lowering and simplifying the crown can enhance water-use efficiency, shoot vigour, and drought resilience in traditional and low-input chestnut orchards.

In the Mediterranean basin, extreme drought events are expected to become more frequent due to climate change. Consequently, selecting and registering forest reproductive material (FRM) adapted to such conditions is crucial to support effective forest restoration. This study aims to identify whether certain seed sources of Quercus exhibit traits potentially advantageous under ongoing climate change. An initial screening of seedlings from five ecologically diverse species from Puglia (southern Italy) was performed to evaluate early-stage responses to drought conditions simulating extreme Mediterranean summer events. Under semi-controlled conditions in a nursery, we evaluated the effect of water removal for 21 days on the growth, physiological, and metabolomic performance of FRM of two seed sources per five Mediterranean Quercus species. Morphological, physiological (SPAD, chlorophyll fluorescence), and metabolic traits (pigments and malondialdehyde) were measured throughout the experimental period and at its end. All Quercus species and their seed sources survived the water deficit and exhibited positive morphological and physiological responses. The effects of seed source were more pronounced in the “Cerris” section than in the evergreen “Ilex” section, making the former species good candidates for afforestation or restoration in Mediterranean areas and valuable material for further research. The high performance of Q. cerris, a species generally considered less drought-tolerant, highlights the Puglia region as a promising source of southern Mediterranean provenances with enhanced resistance to arid conditions.

Urban areas typically experience higher temperatures and reduced precipitation compared to periurban environments, conditions that may strongly influence tree performance. To assess these effects, we studied Pinus pinea in Firenze and Pisa, integrating dendroecological and stable isotope analyses. Ring-width index data did not reveal significant differences in radial growth between urban and periurban trees, suggesting that growth responses alone may underestimate urban stress. In contrast, isotopic analyses provided clearer evidence: δ ¹³ C and δ ¹⁸ O values indicated marked water stress in urban trees, particularly in Firenze, while δ ¹⁵ N and F ¹⁴ C suggested minimal incorporation of traffic-derived nitrogen or fossil CO ₂ , likely due to the protective role of urban parks. These findings highlight an apparent discrepancy, where tree growth suggests resilience, while physiological signals reveal stress linked to urban microclimates. This emphasizes the value of combining multiple indicators to capture tree responses in complex environments. Overall, our results suggest that urban climate exerts a stronger influence on P. pinea than localized traffic emissions, with implications for tree vitality and ecosystem services. Species selection for urban forestry should therefore account for microclimatic constraints to ensure long-term tree performance under ongoing urbanization and climate change.