Inter- and intra-annual patterns of seed rain in the black spruce stands of Quebec, Canada

Abstract

Divergent reproductive strategies of tree species generate differences in the dynamics of seed production and dispersion. The spatial and temporal variability in seed rain abundance and viability was monitored during the period 2000-2007 in four boreal stands in Quebec, Canada. The aim was to compare the inter-and intra-annual patterns of seed dispersal between species with diverging adaptive characteristics and reproductive strategies by testing the hypothesis that sympatric species can exhibit different patterns of seed dispersal according to specific ecological adaptations. The coefficient of variation (CV), representing the inter-annual variability in seed rain, was close to or higher than 1 in balsam fir (Abies balsamea [L.] P. Mill.) and white birch (Betula papyrifera Marsh.) and confirmed the mast seeding habit of the two species. In contrast, CV in black spruce (Picea mariana [Mill.] BSP) ranged between 0.24 and 0.54, indicating a more homogeneous inter-annual amount of seed dispersal because of its semiserotinous cones that preserve seeds for an indefinite period of time. The species showed divergent intra-annual patterns of seed dispersal. Most seed dispersal of the companion species was observed in September-November, while black spruce concentrated seed rain in spring, when the proportion of germinated seeds was higher. Boreal stands experience annual seed rains constituted by a gradual dispersal of seeds of different ages and originating from cones belonging to multiple cohorts. However, asynchronous seed rains in terms of quantity and quality can occur if companion species are associated to the dominant black spruce.

Persistence of balsam fir and black spruce populations in the mixedwood and coniferous bioclimatic domain of eastern North America

“…This contrasts with black spruce, which requires higher numbers of parental trees than does balsam fir. This can be explained by lower black spruce seed inputs compared to those of balsam fir, due the smaller semi‐serotinous cones that are form an aerial seed bank for former, which can release small quantities of seed continuously but episodically with the occurrence of fire (Messaoud, Bergeron, & Asselin, ; Rossi, Morin, Gionest, & Laprise, ). Another explanation may be related to higher seedling mortality within the low light understory for the less shade‐tolerant black spruce.…”

Complexity of Regeneration Dynamic at the Ecocline between Mixedwood and Coniferous Domains of the Southernmost Boreal Zone in Eastern North America

“…This contrasts with black spruce, which requires higher numbers of parental trees than does balsam fir, although the percentage was slightly lower in coniferous bioclimatic domain, especially in clay soil. This might be explained by lower black spruce seed inputs compared with those of balsam fir, due the smaller semi-serotinous cones constituting an aerial seed bank for former, which can release small quantities of seed continuously but episodically with the occurrence of fire [9,46]. Another explanation may be related to higher seedling mortality within the low light understory for the less shade-tolerant black spruce.…”

Factors influencing black spruce reproductive potential in the northern boreal forest of Quebec

“…As with other serotinous species, black spruce has one of the lowest coefficients of variation of temporal seed production of any tree species (cf. Koenig and Knops 2000) as well as relatively lower coefficients of variation of temporal seed dispersal (Rossi et al 2016). Therefore, there are always viable seeds in the aerial multi-cohort seed bank once sexual maturity has been reached.…”