Seed dormancy responses to temperature relate toNothofagusspecies distribution and determine temporal patterns of germination across altitudes in Patagonia

Abstract

Summary Seeds integrate environmental cues that modulate their dormancy and germination. Although many mechanisms have been identified in laboratory experiments, their contribution to germination dynamics in existing communities and their involvement in defining species habitats remain elusive. By coupling mathematical models with ecological data we investigated the contribution of seed temperature responses to the dynamics of germination of three Nothofagus species that are sharply distributed across different altitudes in the Patagonian Andes. Seed responsiveness to temperature of the three Nothofagus species was linked to the thermal characteristics of their preferred ecological niche. In their natural distribution range, there was overlap in the timing of germination of the species, which was restricted to mid‐spring. By contrast, outside their species distribution range, germination was temporally uncoupled with altitude. This phenomenon was described mathematically by the interplay between interspecific differences in seed population thermal parameters and the range in soil thermic environments across different altitudes. The observed interspecific variations in seed responsiveness to temperature and its environmental regulation, constitute a major determinant of the dynamics of Nothofagus germination across elevations. This phenomenon likely contributes to the maintenance of patterns of species abundance across altitude by placing germinated seeds in a favorable environment for plant growth.

Environmental stress, future climate, and germination of Myracrodruon urundeuva seeds 1

“…The germination rate (GR) has commonly been used to obtain the germination limits of seeds of several species (Covell et al, 1986;Bradford, 2002;Arana et al, 2016;Seal et al, 2017Seal et al, , 2018Castillo-Lorenzo et al, 2019) due to its linear relation with temperature (Covell et al, 1986). On account of that, the temperature limits, as well as the sub-and supraoptimum thermal times (Figure 4) could be calculated for germination of M. urundeuva seeds.…”

Temperature and storage time strongly affect the germination success of perennial Euphorbia species in Mediterranean regions

“…Among the endogenous factors, several studies have shown that seed germination is genetically determined and the phylogenetic signal may be a significant constraint to interspecific variation within a genus (Zhang, Du, & Chen, 2004). This was found, for example, for some Romulea species in Mediterranean habitats (Carta, Hanson, & Müller, 2016), even though a contrasting behavior was observed with other genera, such as Stellaria and Nothofagus, which showed considerable interspecific variability in germination behavior (Arana et al, 2016;Vandelook, Van de Moer, & Van Assche, 2008).…”

Adaptation of Forest Trees to Rapidly Changing Climate

“…European beech (Fagus sylvatica L.) is an example of an expansive tree species, and ongoing changes in climate conditions could expand its potential range. Beech stand vitality is high, and its regeneration is well adapted to different site conditions at the limit of the species' distribution; thus, European beech will probably reach its northeastern limit in the future [143].…”