Quality Assurance and measurement errors in monitoring tree crown conditions in Italy.

The adoption of a comprehensive Quality Assurance (QA) programme for tree condition monitoring resulted in a rapid and steady improvement of data consistency in crown transparency assessment. On the other hand, the assessment of damage due to insects and fungi remains problematic and requires further training and control efforts. While our findings demonstrated the benefits arising from a QA programme and even the need to reinforce it, recent financial constrains have resulted in a severe reduction of the field checks. This will render it difficult to obtain a sound estimate of data quality and will jeopardize the results of any statistical analysis aimed at identifying status and trends of tree conditions in Italy.