Research Highlights: Data indicated that fire severity modulates natural regeneration of Cytisus scoparius and Salix atrocinerea communities and drives much stronger effects on the germination of the dominant species. Background and Objectives: Previous studies demonstrated that fire severity induces different behaviours in plant species. Mother plant age is an important feature that must also be considered in plans of forest restoration. The objectives were to determine, in field studies, the effect of fire severity on the natural regeneration of C. scoparius and S. atrocinerea communities, to know the role of mother plant age on the germination of seeds of C. scoparius and S. atrocinerea, and to quantify their germination response at different levels of fire severity, in laboratory settings. Material and Methods: We have analysed the role of fire severity on the natural regeneration of C. scoparius and S. atrocinerea communities considering cover and height. Forty 30 × 30 m plots were randomly located in C. scoparius and S. atrocinerea communities. Fire severity on the germination of dominant species was tested through different levels of smoke, charcoal, ash, and heat. Results: High severity reduced the vertical cover and growth in height of the two communities and favoured the increase of cover of woody species in the C. scoparius community and herbaceous species in the S. atrocinerea community. Mother plant age determined germination percentages of C. scoparius seeds. Germination of C. scoparius was increased by moderate heat, and heat and smoke; and fire severity greatly reduced germination of S. atrocinerea. Conclusions: The regeneration responses after fire were largely controlled by interactions between the fire severity and the individual species regeneration strategies. For restoration purposes, C. scoparius seeds should be treated with 80 °C and smoke for 10 min, in order to increase germination; however, Salix seeds should be used without treatment and immediately after dispersion.

Mixed mountain forests with an uneven-aged structure are characterized by a high tree-growth variability making traditional age-dependent growth models inapplicable. Estimating site productivity is yet another impediment for modelling tree growth in such forests. Uneven-aged mixed-stand forests are known for their high resilience, resistance and productivity, and are being promoted as a suitable alternative to even-aged, pure plantations for climate change adaptation and mitigation. However, their growth must be accurately measured and predicted, but diameter at the breast height (dbh) increment models specifically designed for uneven-aged mixed mountain forests are still rare. Using permanent sampling network data and 465 increment cores, we built two age-independentdbhincrement ( $${i}_{d}$$id ) models for the main species of the study area, namely Norway spruce (Picea abies(L.) Karst.), silver fir (Abies albaMill.) and European beech (Fagus sylvaticaL.). Mixed effects models and the algebraic difference approach were employed to develop $${i}_{d}$$id models based on empirical and commonly used theoretical growth functions. A past growth index was further developed and introduced in the model in order to explain the $${i}_{d}$$id variability. Several mixed effects calibration strategies were assessed in order to obtain the most accurate localized curve for new plots. Tree size, competition and biogeoclimatic variables were found to explain the $${i}_{d}$$id through the empirical growth function, while the growth index significantly improved the theoretical growth function for Norway spruce. The optimization of the calibration strategy for the mixed effects modelling framework enables the growth index implementation in forest practice as an accurate method for estimating site productivity. The accuracy of the two $${i}_{d}$$id models was similar: the root mean squared error of the empirical growth function varied between 0.940 and 1.042 cm for spruce, beech and fir, while the root mean squared error obtained through the theoretical growth function for spruce only was 1.105 cm. The basal area increment prediction at the plot level based on the theoretical growth function reached a root mean squared error of 0.043 m²while using the empirical growth function the root mean squared error is 0.047 m². The high accuracy obtained using age-independent models underlines their suitability for predicting growth in mixed uneven-aged forests. The developed models can be easily integrated into forest practice to accurately obtain $${i}_{d}$$id estimates.

Key message: Divergent patterns of small-scale topsoil organic matter (OM) indicators were identified in mixed vs. monospecific pine forests: tree species identity drives OM quantity, while the C/N ratio is additionally shaped by both overstory and understory diversity. The greater diversity of litter inputs in mixed stands likely accounts for their higher topsoil quality. Context: Mixed forests are increasingly recognized for their potential to enhance soil carbon storage compared to monospecific stands. However, the underlying mechanisms, particularly the combined roles of overstory and understory vegetation, remain poorly understood, especially in Mediterranean pine forests. Aims: We examined how stand type, overstory and understory species composition, and understory richness affect forest-floor biomass and the quantity and quality of topsoil organic matter (OM) in mixed vs. monospecific pine forests at a small scale. Methods: Across six triplets in central-northern Spain (44–151 years old), we established 180 subplots, including monospecific stands of Pinus sylvestris (PS), P. pinaster (PP), and mixed stands (MM). We measured topsoil properties (0–5 cm), forest-floor biomass (25 × 25 cm), understory species composition and richness (1 m ² ), and overstory composition (4 m radius). Results: OM quantity (total organic carbon) followed the stand-scale pattern (PS > MM > PP), driven primarily by tree species identity. However, OM quality (C/N ratio) differed (PS ~ MM > PP), suggesting a combined effects of overstory and understory diversity at small scale. A priming-effect linked to diverse understory litter inputs in MM may partly explain this pattern. Conclusion: Integrated small-scale assessments of all vegetation layers can guide forest management strategies that couple understory conservation with improved soil carbon sequestration in Mediterranean pine forests.

Urbanisation and climate change have intensified the Urban Heat Island (UHI) effect in European cities, increasing thermal stress and health risks, especially for vulnerable people. Nature-based Solutions (NbS), such as green infrastructures (GI), offer effective mitigation strategies. A notable example is the Horizon 2020 URBAN GreenUP project in Valladolid, Spain, where a green shade shelter infrastructure was installed and monitored between 2019 and 2022 to evaluate its cooling performance and its effects on temperature-based urban heat indicators through the use of Key Performance Indicators (KPIs). Local thermal conditions were monitored across two adjacent narrow streets—one with the green shade shelter and one as a control. The installation of the green shade shelter in Valladolid produced measurable thermal benefits. During summer peaks, it reduced ambient temperatures by approximately 0.9 °C, with daily maximum temperatures decreasing by 1.0–3.0 °C. In winter, daily minimum temperatures dropped by around 1.0 °C, while autumn saw an increase of 0.7 °C. Summer minimum temperatures varied, ranging from a 0.2 °C decrease in early summer to a 0.7 °C increase in late summer, with a 0.3 °C rise during peak summer in mid-July. The intervention also reduced the frequency and delayed the onset of days exceeding 35 °C and nights above 20 °C, although the delay in peak tropical nights was limited to seven days. These findings indicate that green shade shelters can contribute to improving street-level thermal conditions and reducing temperature-based heat exposure indicators in dense urban environments.