Synchronisms and correlations of spring phenology between apical and lateral meristems in two boreal conifers

Abstract

Phenological synchronisms between apical and lateral meristems could clarify some aspects related to the physiological relationships among the different organs of trees. This study correlated the phenological phases of bud development and xylem differentiation during spring 2010-14 in balsam fir (Abies balsamea Mill.) and black spruce [(Picea mariana Mill. (BSP)] of the Monts-Valin National Park (Quebec, Canada) by testing the hypothesis that bud development occurs after the reactivation of xylem growth. From May to September, we conducted weekly monitoring of xylem differentiation using microcores and bud development with direct observations on terminal branches. Synchronism between the beginning of bud development and xylem differentiation was found in both species with significant correlations between the phases of bud and xylem phenology. Degree-day sum was more appropriate in assessing the date of bud growth resumption, while thermal thresholds were more suitable for cambium phenology. Our results provide new knowledge on the dynamics of spring phenology and novel information on the synchronisms between two meristems in coniferous trees. The study demonstrates the importance of precisely defining the phases of bud development in order to correctly analyse the relationships with xylem phenology.

Warming counteracts defoliation‐induced mismatch by increasing herbivore‐plant phenological synchrony

“…For spruce budworm, the optimal phenological matching occurs when larval emergence precedes balsam fir and white spruce budburst by about 2 weeks (Lawrence, Mattson, & Haack, ). In general, bud phenology in black spruce occurs 2 weeks after that of balsam fir (Antonucci et al, ); this delay is a major factor explaining the lower damage of black spruce relative to balsam fir. However, this 2 week delay in black spruce budburst decreased with warming.…”

“…Photoperiod was maintained at 18 hr during the experiment. A 12°C temperature with a photoperiod of 18 hr is representative of conditions during the budbreak phase in the southern limit of the boreal forest in Quebec (Antonucci et al, ; De Barba, Rossi, Deslauriers, & Morin, ). We installed a white net (Proteknet 60 g, 1.9 mm × 0.95 mm) in the middle of each chamber.…”

Tree Height-Diameter Relationships in the Alpine Treeline Ecotone Compared with Those in Closed Forests on Changbai Mountain, Northeastern China

“…It has been reported that when soil temperature is lower than 5 • C, a very small reduction in soil temperature may lead to a dramatic increase in the time required for mitotic division of plant cells and a doubling in the time needed for cell reproduction [27]. Moreover, resource allocation from storage tissues to a tree's apical meristems (height growth) yields a relatively lower reward relative to xylem (radial growth) due to the longer transport pathway [28]. Therefore, an abrupt change in tree stature at a temperature threshold seems to be possible.…”

“…This indicates that stature change of treeline birch is size-specific. Previous research has shown that the susceptibility of the apical meristem to cold conditions is the underlying cause of height limitation [28]; however, once the low temperature limit is broken (i.e., climate conditions become warmer), shrubby forms with multiple meristems are expected to display more hysteresis than upright forms. Saplings may also be less sensitive to warmer air temperature, because they are constrained more by ground temperature.…”

The onset of xylogenesis is not related to distance from the crown in Smith fir trees from the southeastern Tibetan Plateau

“…11 However, a direct relationship between the timing of budburst and xylem formation 12 has not always been detected. In conifers, the onset of xylem formation can occur 13 either before or after bud break (Fahn and Werker 1990, Rossi et al 2009, Cuny et al 14 2012, Zhai et al 2012, Antonucci et al 2015. 15 Auxin is transported basipetally from the developing buds into the subjacent stem, 16 inducing the production of xylem cells.…”