EFFECTS OF ENVIRONMENTAL-FACTORS ON THE SHOOT DEVELOPMENT OF QUERCUS-PETRAEA SEEDLINGS - A METHODOLOGICAL APPROACH

The objective of this study was to determine if various morphological components of height growth were sensitive to environmental factors (i .e., grass root competition, frost and shading) and to see if these co mponents could be used to quantify the effect of environmental stress on the height growth of sessile oak (Quercus petraea Liebl.) seedlings . The following components were measured: number of flushes produced o n the main stem, length of the growth unit (GU) developed during each flush, annual GU length, number of nodes per GU, and state of the term inal bud of each GU. The number of flushes produced was reduced by all environmental treatments. The annual GU length was positively related to the number of flushes produced. Grass competition reduced GU lengt h in each flush and therefore reduced annual GU length. On the other h and, partial shading increased GU length in each flush and annual GU l ength. Number of nodes was not apparently affected by environmental fa ctors and was positively related to GU length. Where factors that affe ct terminal bud mortality were partially controlled (i.e., in grass co mpetition and shading experiments), mortality rate was low (5% for GUs of the first flush in grass competition experiment), but in the frost experiment terminal bud mortality rate was higher (64% for GUs of the first flush). The sensitivity of the different morphological componen ts to environmental factors and the quantification of the effects of t he factors using generalized linear models were discussed. (C) 1997 El sevier Science B.V.