Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests. Part V. Tree Growth

updated: 05/2010

Hamburg

2010

29 S.

Bandaufführung

10811S

170921

The growth of trees is a key ecological parameter of forests and thus of high importance as an indicator of forest condition. This manual focuses on growth assessment within Level II plots. On Level I plots of the large scale assessment no periodic tree size measurements have yet been made. Increment is defined as the growth of trees (shoots in coppice forests) and stands within a defined period and can be expressed as increment of diameter, basal area, height and/or volume. These parameters can be linked to external as well as internal factors serving as a proxy parameter for the reaction of trees and stands to changes in site and environmental conditions. As the assessments are carried out on fixed plots the calculation of area related estimates is possible. The advantages before other proxies lie in their direct economical and ecological importance. Tree growth is grouped here into periodic increment of all trees on the plot and permanent or continuous tree diameter change of selected trees. In addition to these measurements past growth can be reconstructed using the well developed methods of dendrochronology and may be used as a proxy for past environmental conditions. In addition to growth, stand structure provides information for the interpretation of other assessments carried out, such as development of ground vegetation, crown defoliation, throughfall and others. 2. Scope and application This part of the Manual aims at providing a consistent methodology to collect high quality, harmonized and comparable data at Level II monitoring plots on growth of trees and stands (Table 1). Harmonization of measurements and data processing procedures is essential to ensure comparability of results. To have their data used in the international database and evaluations, National Focal Centres and their scientific partners participating to the UNECE ICP Forests programme should follow the methods described here.