**Preface**

A present and urgent challenge is to follow the major guidelines set out for forest resource sustainability management in the context of both ecosystem-related global warming threats and green economy needs. For instance, we may need to pay special attention to threatened species and lesser-known endemic species, as well as to invasive species that may be profitable when managed, so as to avoid the overexploitation of current forest species. Additionally, the full resource use approach requires consideration of the residual materials from forest management and related industries, taking into account different tree components and non-wood products that present enormous diversity.

Specific knowledge on these diverse materials regarding their structure, anatomy and properties is, therefore, an essential tool in assessing the potential and suitability of these different forest resources. For the most profitable forest species, research over the years has produced a number of studies related to general wood growth tendencies and characteristics. However, different species might need to be involved in the framework of new ecosystem-oriented approaches for sustainable resource management. The high diversity within and between species also requires careful study of their variability, which may contribute toward a better understanding their properties and potential applications, thereby supporting improved tree selection and breeding programs.

This Special Issue aims to gather research-based data on wood and on non-wood forest products, with a special emphasis on bark—specifically, its anatomical, physical and chemical properties and their relationships—to provide tools and background information to assess the forest resource potential of different species. Our aim is twofold, as we look to contribute to efforts to increase forest sustainability and diversity through preserving species with potential for high-quality end use and to diversify wood supply using knowledge related to wood and non-wood characteristics and their diversity.

## **Vicelina Sousa, Helena Pereira, Teresa Quilh ´o, and Isabel Miranda** *Editors*
