A canonical model of tree resource allocation after defoliation and bud consumption

This paper presents a model of resource allocation in mountain birch (Betul a pubescens ssp. czerepanovii (Orlova) Hamet-Ahti), and uses the model to s imulate tree responses to defoliation and bud consumption. The model simula tes growth of mountain birch individuals that renew by basal sprouting afte r being severely attacked by geometrid larvae. The model was constructed by using a canonical approach that takes into account only qualitative inform ation on the processes that govern plant growth. Although the model was par ameterised with data from intact trees, it reproduced qualitatively correct and quantitatively reasonable numerical responses to different types of he rbivory. In general, the responses were in good agreement with experimental held results, although some of the long-term responses could not be verifi ed due to lack of appropriate data. This study demonstrated that, if suffic ient qualitative information is available, canonical modelling can be used to successfully simulate tree functioning in a mechanistic way even though the physiological processes behind the yearly nitrogen budgets and shoot nu mbers of whole trees are not explicitly included in the model. (C) 2000 Els evier Science B.V. All rights reserved.