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

Abstract

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.

Harmonizing forest inventories and forest condition monitoring - the rise or the fall of harmonized forest condition monitoring in Europe?

“…This also mean common training, and Quality Assu rance/Quality Control (e.g., Bussotti et al 2009, Gasparini et al 2009). With the simple harmonization of assessment/measurement methods, datasets will be harmonized in terms of attributes and measurements, but not necessarily they can be integrated to ob tain a single population estimate.…”

Consistency of defoliation data of the national training courses for the forest condition survey in Germany from 1992 to 2012

“…Innes (1993), Ferretti et al (1999), and Solberg and Strand (1999) came to similar results during field checks in Great Britain (1988), Italy (1996), and Norway (1990–95), respectively. In contrast, Bussotti et al (2009) found that more than or equal to 90 % of the assessments during the field control in Italy from 1999 to 2004 fell between ±10 % with respect to the reference team. In recent times, the prescribed aim (data quality limit) of ICP Forests for field checks during the forest condition survey was set to at least more than or equal to 70 % of assessments that must not deviate more than ±10 % from one another (Eichhorn et al 2010).…”

“…field checks) are believed to remove a great amount of subjectivity and variation among individual observers (Innes 1993; Köhl 1991; Schöpfer 1985b). For instance, a rapid and steady improvement of defoliation data consistency in Italy following the adoption of the QA programme was reported by Bussotti et al (2009). …”

“…In fact, pronounced deviations (more than ±20 % defoliation) from the mean were not observed during the last three years. Proportions determined during the national training courses in Italy and the South European training courses between 1996 and 2004 were slightly lower ranging from 80 to 90 %, and a marginal increase in the proportion was observed over time (Bussotti et al 2009). The proportions calculated in the present study are high in comparison to those reported in the literature from the second assessments by a control team during field checks.…”

The conditions of forests in Italy. Results from the extensive surveys of Level I (1997-2010)

“…Infatti nel 1996 è stata operata una profonda revisione dei metodi di lavoro, dei criteri di valutazione, dell'addestramento del personale e della verifica della qualità dei dati (Quality Assurance -QA). La procedura QA applicata è basata sui seguenti punti (Bussotti et al 2009): (i) aggiornamento costante del manuale di valutazione secondo i problemi che emergono di volta in volta; (ii) corso annuale di addestramento per il personale addetto ai rilievi, da tenersi prima dell'inizio dei rilievi; (iii) controllo in corso d'opera di una parte delle aree di saggio per verificare il livello di ripetibilità del dato.…”