Annual-shoot growth and branching patterns in Nothofagus dombeyi (Fagaceae)

Abstract

During the growing seasons 1994-1995 and 1995-1996, weekly measures of length and number of internodes and morphological observations were made on annual shoots of 11- to 21-year-old Nothofagus dombeyi (Mirb.) Blume trees growing in northern Patagonia, Argentina. Growth period and shoot size at the end of the extension period were highly variable. Four main types of annual shoots could be identified according to the death or persistence of the apical meristem and the development or not of axillary branches during the growth season of main stem extension. For all shoots the maximum growth rate took place in late November and was followed by a slower growth rate or cessation of growth in early December to early January. For those shoots with a long growth period, a second growth peak took place in late January-February, and only those shoots with a growth rate higher than 35-40 mm/week developed axillary branches as they elongated. Results from bud dissections suggest that the early growth rate peak corresponded to the development of those structures preformed at the time of bud break. The death of the apical meristem of a shoot affected both the position and the relative size of axillary branching on that shoot.Key words: Nothofagus, annual shoot, growth dynamics, branching pattern.

Shoot development and dieback in progenies of Nothofagus obliqua

“…The abscission of the terminal bud of the first-year shoot without dieback in N. obliqua proved to impact negatively on the size of the second shoot. This result contrasts with that of a study on N. dombeyi saplings, in which shoots of terminal and distal axillary origin reached similar sizes [24]. This discrepancy may indicate a difference between these species regarding the allocation of resources among the distal buds of a shoot; age differences between the plants included in both studies may also be implicated.…”

“…Specific trees might be more suited as seed sources depending on the region of forestry establishment. The extension period of long shoots of this and other Nothofagus species proceeds until late summer and early autumn [24]. These shoots might be more susceptible than shorter shoots to early frost hazards.…”

Biomass accumulation and allocation in seedlings of three Nothofagus species at the edges of a light gradient in canopy gaps of a Subantarctic forest

“…Para el análisis de la edad de los renovales de Nothofagus (diá-metro a la base del tallo < 5 mm), se extrajeron de cada especie y en forma aleatoria 30 plantas intactas del norte y 30 del centro de los sectores planos de los claros seleccionados (3 especies × 4 claros × 2 posiciones × 30 renovales = 720 renovales en total). Estas plantas se herborizaron y se les determinó la edad mediante la técnica del conteo de las cicatrices dejadas por las escamas de la yema anual (Puntieri et al, 1998). Cuatro renovales del norte de N. nervosa y tres renovales de N. obliqua (2 del norte y 1 del centro) se deterioraron durante la herborización.…”

Effects of artificial damage on the branching pattern of Nothofagus dombeyi (Nothofagaceae)

“…(Nothofagaceae) is a relatively abundant evergreen, forest tree species from temperate South America. The basic architecture of this species has been studied in recent years [39,42,43,45]. By mid-summer, at the end of its extension period, each shoot of N. dombeyi bears one axillary bud at all but its most proximal nodes (sylleptic branches may be borne by the most vigorous shoots, usually those of the trunk).…”

“…By mid-summer, at the end of its extension period, each shoot of N. dombeyi bears one axillary bud at all but its most proximal nodes (sylleptic branches may be borne by the most vigorous shoots, usually those of the trunk). A terminal bud may also develop but spontaneous apex deaths are very frequent [39]. Each bud of a shoot generates an offspring shoot in the spring following that in which the parent shoot extended; the size of the offspring shoots derived from a common parent shoot usually decreases as the parent shoot's proximal end is approached, as in many other tree species [6,9,39,41,42,45].…”