tailieunhanh - Báo cáo khoa học: "growth in a sweet chestnut (Castanea sativa Mill.) coppice"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài:"growth in a sweet chestnut (Castanea sativa Mill.) coppice. | 301s Ann. Sci. For. 1989 46 suppl. 301s-304s Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Fine root growth in a sweet chestnut Castanea sativa Mill. coppice p. Montpied Laboratoire d Ecologie Végétale CNRS URA121 Université Paris-Sud Orsay France Introduction The root growth and turnover of fine roots are known to be a major carbon pathway in forest ecosystems Fogel 1985 . Dubroca 1983 showed that the carbohydrate reserves play a major role in both above- and belowground growth of a sweet chestnut Castanea sativa Mill. coppice. The aim of this study was to examine fine root phenology of a chestnut coppice with an emphasis on the influence of coppicing. weekly until early August and then every 2 wk until November by means of mapping all roots visible behind the glass on a transparent plastic sheet. A distinction was made between long roots and laterals the former being defined as the ones bearing the latter. Results The patterns of fine root growth in the older coppices 5 and 16 yr coppices can be divided into 4 overlapping phases. Materials and Methods This study took place in a sweet chestnut coppice 30 km sw of Paris growing on an illuvi-ated acid soil. 5 vertical rhizotrons 40 cm wide 50 cm deep were built in March 1985 each of them facing a stump of average size at a distance of 1 m. One of them faced a stump entering its 1st year after coppicing no. 1 2 others faced 5 yr stumps nos. 5 and 5 and the last 2 faced 16 yr stumps nos. 16 and 16 . As soon as the first roots appeared root growth was recorded Phase I initiation of long roots June This phase began when the first roots appeared in early June viz. mo after bud burst and was completed in late June the destruction of roots during that period in rhizotrons 5 and 16 when a rodent dug a gallery behind the glass prevented the root system from fully developing until the end of the growing season Fig. 1 . Since the destroyed roots were not replaced after that period it appeared to be critical. .