This review focuses on tree health assessment in urban forest, specifically on the methodologies commonly used to detect levels, dimensions, and location of wood deterioration. The acknowledged benefits to the urban forestry area from the application of assessment techniques are also addressed. A summary is presented of the different methodologies, such as visual analyses, acoustic tomography, and digital wood inspection drill, with the underlined importance of the biodeterioration of wood by fungi and termites.

Within-stem variation in the mechanical properties of Portuguese oak wood was analysed, considering different locations (three sites in the centre and north of Portugal—Site 1, Site 2, Site 3) and positions within the tree (two distances to pith—P1, P2). The study comprised compression parallel to the grain, bending strength and modulus of elasticity. Ultimately, this study aims at assuring the building of a body of knowledge on the technological quality and processing options for this species. The results showed for one provenance, Site 1, a significant effect of the distance to pith in the mechanical properties, which can be related to a different soil composition. For this provenance, a decrease in the compression and bending strength was verified from pith to bark. For the other provenances (Site 2 and Site 3), no effect was noticed. The overall behaviour showed noticeable correlations between the mechanical properties and density.

This paper addresses the problem of summer branch drop (SBD) in urban forests, namely through detecting the causes of this unpredictable event, aiming at preventing and increasing the control of this phenomenon, while using the most recent methodologies to detect wood deterioration, namely visual tree assessment (VTA), drilling resistance, and acoustic tomography, in an isolated and associated way. The study considers events in the cities of Arcos de Valdevez in Viana do Castelo district (Site 1), Ponte de Lima in Viana do Castelo district (Site 2), Montemor-o-Novo in Évora district (Site 3), and Paços de Ferreira in Porto district (Site 4), targeting trees of public interest. Given the phytosanitary condition recognized using nondestructive equipment, a set of measures for the preservation of the tree elements and their history are suggested. SBD is mostly related to internal degradation. A VTA diagnosis, applied in isolation, could lead to an incorrect prognosis of the internal degradation. So, it is important to confirm of the presence of biotic agents through equipment (acoustic tomography and drilling resistance). Even with instrumental diagnostics, for reducing the subjectivity of the approach to estimating the SBD, a global analysis is necessary, including dendrometric parameters, predisposing or inciting factors, lower tree defences against internal degradation due to environmental conditions, and biotic agents.

Organização: Adilson Tadeu Basquerote Silva, Érica de Melo Azevedo e Roger Goulart Mello ISBN: 978-65-5364-118-1 Ano: 2022

The structural stability of urban trees can be significantly affected by internal decay and open cavities, highlighting the need for reliable assessment methods. Traditional evaluations often rely on simplified analytical formulas to estimate strength loss caused by trunk defects. In parallel, computational biomechanical models have emerged as powerful tools for simulating tree behaviour under loading and for quantifying failure risk. This study evaluates the agreement between classical empirical strength-loss equations and structural simulations generated by a biomechanical model for 80 urban trees representing 21 species affected by trunk defects. Strength-loss estimates, derived from literature-based equations, were calculated using non-destructive diagnostic data, including tomographic imaging and resistance drilling. These results were then compared with model-based estimates of failure probability under wind loading. The findings indicate that equations incorporating cavity eccentricity, as well as formulations accounting for geometric asymmetry and the residual strength of decayed wood, produced estimates more consistent with the biomechanical simulations obtained for this sample. Overall, the results highlight the importance of considering cavity position and material degradation when estimating strength loss. The integration of tomographic diagnostics, resistance drilling, structural modelling, and refined analytical formulations can improve the mechanical interpretation and transparency of urban tree stability assessments.