Habitat specialization through germination cueing: a comparative study of herbs from forests and open habitats

Abstract

Annual changes in temperature and light regime in temperate forest delimit windows of opportunity for germination and establishment. Germination strategies of forest plants are adaptations to utilize such narrow windows in time. Conversely, lack of fit between germination ecology and environment may explain why species of open habitats generally fail to establish in forests. Germination strategy should be considered an important mechanism for habitat specialization in temperate herbs to forest habitats. The findings strongly suggest that phases in the plant life cycle other than the established phase should be considered important in adaptive specialization.

Exploring the effects of pasture trees on plant community patterns

“…Seeds were expected to germinate better outside compared to beneath canopies (Ten Brink et al., ). In contrast, we found no clear negative effects of canopy presence on germination success in general, but only for the light‐dependent species Galium verum and Filipendula vulgaris .…”

“…Germination success is driven both by the environmental context and species traits, especially seed mass, which contribute to the wide range of responses among grassland species to environmental conditions (Wagner et al., ). Large‐seeded species have a germination advantage over small‐seeded species in relation to canopy shading (Bruun & Ten Brink, ; Ten Brink, Hendriksma, & Bruun, ; Westoby, Falster, Moles, Vesk, & Wright, ). In addition, other environmental factors related to specific tree species, e.g., nutrient shortage, drought and litter cover, have more pronounced effects on small‐seeded species (Dzwonko & Gawroński, ; Westoby et al., ).…”

“…Nevertheless, a laboratory experiment by Ten Brink et al. () showed that forest species tend to have greater germination success in dark compared to open habitat species among species with seeds smaller than ~1 mg, suggesting a stronger link between light requirement for germination and shade tolerance for the mature plant in small‐seeded species. In another experiment, Silvertown () found that 17 out of 27 species had a lower germination success under leaf canopies compared to darkness, due to how leaves change light transmittance and the red/far red ratio of light (Smith, ).…”

“…We combine this experiment with an analysis of understorey plant communities of wooded pastures in the same region, including the pastures used in the seed sowing experiment. We hypothesise that: (a) seeds of the selected species generally germinate better outside tree canopies (Ten Brink et al., ); (b) the effect of canopy presence on germination success depends on tree species (Thomaes et al., ); (c) germination success is positively affected by species’ shade tolerance as adults (Bruun & Ten Brink, ; Ten Brink et al., ); (d) large‐seeded species have greater germination success under canopies compared to small‐seeded species (Bruun & Ten Brink, ; Ten Brink et al., ); and (e) few species show similar response to canopy cover at the germination stage as they do in the mature plant community due to weak links between how canopy cover affects germination success and occurrence in the understorey plant community (Figueroa & Lusk, ).…”

Habitat Differentiation Between Drosera anglica and D. rotundifolia in a Post-Mined Peatland, Northern Japan

“…The establishment of D. anglica requires higher water-table levels compared with D. rotundifolia (Nordbakken 1996; seedling survival determine the habitat preference and distribution (Poorter 2007;ten Brink et al 2013), with ecologically 'safe' sites showing differences between seed germination and seedling growth (Dalling et al 2001;Eriksson 2002). In wetlands, seed germination rates are often determined by water levels (Keddy 2010), whereas seedling growth is inhibited by environmental stress, such as drought and inundation (Coops and van der Velde 1995; Anderson et al 2009).…”