Environmental filtering drives the shape and breadth of the seed germination niche in coastal plant communities

Abstract

Environmental filters shape the germination niche to prevent emergence in the season of highest threat for seedling establishment. The germination niche breadth is narrower in the communities with stronger environmental filters, but only in beaches. This study provides empirical support to a community-level generalization of the hypotheses about the environmental drivers of the germination niche. It highlights the role of germination traits in community assembly.

Variation in the seasonal germination niche across an elevational gradient: the role of germination cueing in current and future climates

“…Moreover, stratification increased the range of temperatures for germination in high‐elevation populations, consistent with results of Fernandez et al. (). However, stratification is not an appropriate germination cue for low‐elevation populations, since waiting until after winter chilling would vastly shorten the time for growth and reproduction before the onset of summer drought.…”

“…Instead, lower‐elevation populations germinated across a broad range of temperatures, with or without stratification. These results also correspond with the expectation that germination niches are narrower when cues are more reliable or more predictive of approaching favorable conditions (Barga et al., ; Fernández‐Pascual et al., ). It is interesting that precipitation variability seems more important for predicting levels of maximum germination (i.e., dormancy), but that we saw strong plasticity in response to temperature cues, suggesting that temperature could be a more reliable cue of seasonal conditions than precipitation for these populations.…”

“…However, the optimal response to temperature cues may vary with climate among populations. Although clinal within‐species variation in dormancy and germination traits is often reported (Montesinos‐Navarro et al., ; Vidigal et al., ; Barga et al., ; Fernández‐Pascual et al., ; Hernández et al., ; López et al., ), fewer studies have examined intraspecific variation in seed chilling responses, particularly across climatic gradients (Cavieres and Arroyo, ; Debieu et al., ; Rubin and Friedman, ). Our results demonstrate extensive variation in stratification (chilling) requirements and ambient temperature responses in S. tortuosus populations across elevation.…”

“…For example, dormancy may be gradually released in response to experiencing a period of after-ripening at warm temperatures, which can act to prevent germination of summer-dispersed seeds until favorable fall conditions (Baskin and Baskin, 2014;Huang et al, 2016;Vidigal et al, 2016;Finch-Savage and Footitt, 2017). Conversely, seed dormancy may also be released by exposure to low temperatures, which may prevent germination from occurring until spring (Penfield and Springthorpe, 2012;Fernández-Pascual et al, 2017). As dormancy is lifted by these cues, germination can be induced by additional cues such as light under an increasing range of temperature and water availability.…”

The functional trait spectrum of European temperate grasslands

“…However, our knowledge of plant trait ecology is largely focused on few traits concerning aboveground vegetative growth and morphology, and very few studies have assessed the potential role of regeneration traits (Jiménez‐Alfaro, Silveira, Fidelis, Poschlod, & Commander, ; Larson & Funk, ; Poschlod et al., ; Saatkamp et al., ). Regeneration traits have been long acknowledged as relevant to the natural maintenance of biodiversity (Grubb, ), and have been found to be important for both species coexistence and species sorting (Bernard‐Verdier et al., ; Fernández‐Pascual, Pérez‐Arcoiza, Prieto, & Díaz, ; Pierce, Bottinelli, Bassani, Ceriani, & Cerabolini, ). Processes captured by regeneration traits including flowering, seed production, clonal growth, dispersal, germination, and growth rates are relevant to community assembly, species turnover, survival and persistence (Klimešová, Tackenberg, & Herben, ; Pohl, Stroude, Buttler, & Rixen, ; Poschlod et al., ).…”