Perspectives: State of national forest damage survey programmes in Europe and ways toward improved harmonization and data sharing

Recent increases in forest damage across Europe have challenged national forestry sectors and threatened progress toward Europe's climate and bioeconomy goals. Although developments in remote sensing now allow large-scale wall-to-wall monitoring of forest conditions, reliable damage assessments still require robust terrestrial data. Yet, existing data often remain inconsistent and fragmentarily distributed across institutions and countries. Based on consultations with national experts, we here provide an evaluation of national forest damage survey programmes in 19 European countries, identify obstacles that hinder more effective use of data, and formulate recommendations to overcome these barriers. We examined five aspects of national forest damage surveys: (i) legal and institutional frameworks, (ii) data acquisition methods, (iii) damage attribution, (iv) data quality and consistency, and (v) data accessibility. We found that half of the examined programs have changed protocols since 2000 and only 53 % of countries currently have survey programs covering their entire forest area. In 26 % of countries, legal constraints hamper data accessibility to the broader international community, while in 89 % data are available only in the respective national languages. In 84 % of countries, the absence of adequate metadata hinders the usability of the data without inside knowledge. Some of Central European countries operate the most consistent and open systems, while western and northern countries generally exhibited lower levels of openness and consistency. The implementation of coordinated structural changes in national programs that would enable consistent monitoring of forest damage at European level is unrealistic in the foreseeable future. However, certain critical gaps in data coverage, completeness, and consistency can be addressed through extensive data post-processing and integration with remote sensing. Overcoming barriers, such as limited awareness of the importance of transnational assessments, requires improved communication efforts and targeted funding programs. Establishing a coordination unit by leveraging existing policy processes in Europe appears essential to advancing these efforts.