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Doctoral thesis, 2011

Monitoring forest damage

Wulff, Sören;


The aims of the work this thesis is based upon were to assess past and current methods of monitoring forest damage in Sweden and to propose key components of a new monitoring system that would be better adapted to the information requirements. A utilitarian perspective is adopted in the thesis, thus forest damage is defined as anything that reduces the vitality of trees in a forest or their economic value. Similarly, the term forest condition is used to describe the extent to which damage has reduced the vitality of trees, as assessed (largely) through crown defoliation. Evaluation of the accuracy of large-scale monitoring of forest condition showed significant differences between observer teams, although on average their assessments did not significantly differ from a national standard. The results indicate that the long-term development of forest condition is the most important information that can be obtained from these kinds of inventories. Short-term fluctuations are difficult to interpret, since they may be due to extreme weather events or assessment variability. Large-scale monitoring, such as that performed in national forest inventories, has good potential for estimating geographical distributions, areas, and causes of extensive damage outbreaks. In major outbreaks even gradual changes of damage levels can be estimated with relatively high precision. However, large-scale monitoring also has limitations. To meet current information needs, assessments of forest damage must be timely and be made at several spatial scales. Thus, in addition to broad monitoring programmes that provide time-series information on specific type of damage and their causes, there is a need for local and regional inventories adapted to specific damage events. In this way data can be obtained to support not only general strategic decisions but also specific regional and local mitigation programmes which are likely to become increasingly important following anticipated climate changes. To meet the information needs a new Swedish forest health assessment system is proposed that includes several interacting components targeting the information requirements for strategic and operational decision-making, and accommodates a mechanism for continuously expanding the knowledge base.


forest pathology; plant condition; plant diseases; monitoring; forest inventories

Published in

Acta Universitatis Agriculturae Sueciae

2011, number: 2011:97
ISBN: 978-91-576-7641-2
Publisher: Department of Forest Resource Management, Swedish University of Agricultural Sciences

Authors' information

Swedish University of Agricultural Sciences, Department of Forest Resource Management

UKÄ Subject classification

Forest Science

URI (permanent link to this page)