Gianfranco Fabbio

Changes in foliar carbon isotope composition and seasonal stomatal conductance reveal adaptive traits in Mediterranean coppices affected by drought

We estimated water-use efficiency and potential photosynthetic assimilation of Holm oak (Quercus ilex L.) on slopes of NW and SW aspects in a replicated field test examining the effects of intensifying drought in two Mediterranean coppice forests. We used standard techniques for quantifying gas exchange and carbon isotopes in leaves and analyzed total chlorophyll, carotenoids and nitrogen in leaves collected from Mediterranean forests managed under the coppice system. We postulated that responses to drought of coppiced trees would lead to differential responses in physiological traits and that these traits could be used by foresters to adapt to predicted warming and drying in the Mediterranean area. We observed physiological responses of the coppiced trees that suggested acclimation in photosynthetic potential and water-use efficiency: (1) a significant reduction in stomatal conductance (p<0.01) was recorded as the drought increased at the SW site; (2) foliar δ13C increased as drought increased at the SW site (p<0.01); (3) variations in levels of carotenoids and foliar nitrogen, and differences in foliar morphology were recorded, and were tentatively attributed to variation in photosynthetic assimilation between sites. These findings increase knowledge of the capacity for acclimation of managed forests in the Mediterranean region of Europe.

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.

Monitoring managed forest structure at the compartment-level under different silvicultural heritages: An exploratory data analysis in Italy

ABSTRACT The more and more diffused multifunctional role addressed nowadays to public forests, calls for targeted analysis aimed at highlighting the overall outcome of different practices implemented on the same forest compartment, according to the locally prevailing function. This study was carried out in four Italian beech forests across a latitudinal gradient representative of multiple management history, stand structure, and dominant stand age. We analyze forest structure at the compartment scale before and after silvicultural practices. We aim to explore relationships and similarities between 10 stand attributes (mensurational and structural variables) to identify relevant indicators for the monitoring and management of forest ecosystems. Results indicate changing patterns of correlation and similarity among mensurational variables following practice implementation. A sensitivity gradient to silvicultural practice was finally identified within the four sites investigated as a result of the diverging stand structure. Our approach suggests a way and provides an insight for the design of adaptive forestry management practices required to meet environmental targets, in addition to the already acknowledged supply of primary goods and services.

Exploratory analysis of structural diversity indicators at stand level in three Italian beech sites and implications for sustainable forest management

The present study introduces an exploratory data analysis based on structural indicators with the aim to assess the effect of silvicultural practices on tree stand structure. The study was carried out in three Italian beech forests of different ages with stand structures that originated from dissimilar regeneration and cultivation techniques (Cansiglio, northern Italy, Chiarano, central Italy, and Mongiana, southern Italy). Ten structural indicators were considered when investigating the latent multivariate relationship between stand structure attributes before and after thinning operations by using a multiway factor analysis (MFA). The MFA results identified the older stand at Cansiglio as more homogeneous for cultivation regimes, and more stable to practices when compared with the younger sites (Chiarano and Mongiana). Heterogeneous stands were sensitive to silvicultural practice thus suggesting their possible impact on forest attributes. The proposed approach proved to be an operational tool to evaluate comprehensively the response of forest structure to planned interventions.