Germination in five shrub species of Maritime Pine understory—does seed provenance matter?

Abstract

& Context Maritime Pine forests cover important mountain areas in Portugal and are known to be a particularly fireprone forest type. Understory composition plays an important role in maintaining biodiversity and ecosystem services after recurrent wildfires. & Aims This study aims to improve the knowledge on the germination ecology of understory species of Maritime Pine forests, focusing on the importance of seed provenance, including in relation to germination enhancement by heating. & Methods The selected species were Cistus ladanifer L., Erica australis L., Erica umbellata L., Pterospartum tridentatum L. (Willk), and Genista triacanthos Brot. Seeds were collected from two or three distant populations. Besides a control treatment, two heating regimes were applied, i.e., 100°C during 5 min and 80°C during 30 min. & Results Heating treatments significantly enhanced germination in four out of the five species. Differences between provenances were most evident for C. ladanifer and E. australis, especially following the heating treatments. Overall, the seeds from the southern provenances germinated better and, at the same time, were smaller. & Conclusion The present results confirmed that seed provenance should not be ignored as a key factor in germination ecology, so that further work is needed to untangle the roles of environmental and genetic factors in the observed differences between provenances.

Germination response of woody species to laboratory-simulated fire severity and airborne nitrogen deposition: a post-fire recovery strategy perspective

“…Meanwhile we found no differences in the average time of seed germination of P. tridentatum between the two heat shocks and the control treatment, but significantly greater germination time for H. lasianthum after exposure to both the moderate-and high-severity thermal shocks. Contrary to our expectations and other findings (Rivas et al 2006;Vasques et al 2012), P. tridentatum, a facultative-seeder species with high-resprouting ability, had heat-stimulated germination rates just after submission of the seeds to the highest temperatures (120 °C for 5 min) under laboratory conditions, but equal average germination times. This may indicate that the light thermal shock (60 °C for 5 min) applied to simulate a moderate-severity fire was insufficient to promote significantly greater percentages and faster times of seed germination of this species consistent with Valbuena and Vera (2002).…”

Local climate controls among-population variation in germination patterns in twoEricaspecies across western Iberia

“…E. australis, E. umbellata) (González- Rabanal and Casal, 1995;Trigueros-Vera et al, 2010), although not all populations respond in this way (Valbuena and Vera, 2002). Exposing the seeds of these species to a heat pulse or moderate temperatures for long periods has shown to significantly increase germination in some cases (González-Rabanal and Casal, 1995;Cruz et al, 2003;Trigueros-Vera et al, 2010;Vasques et al, 2012), but, again, not all populations studied responded similarly, and other studies reported no such effect (Valbuena and Vera, 2002;Moreira et al, 2010;Vasques et al, 2012). Erica australis is a resprouter species which forms a soil seed bank (Torres et al, 2012), but recruitment after fire is minimal (Céspedes et al, 2014).…”

Provenance and seed mass determine seed tolerance to high temperatures associated to forest fires in Pinus pinaster

“…The maritime pine (Pinus pinaster Aiton) is a very inflammable conifer species with high resin content that constitutes one of the principal fire-prone forest ecosystems of the Iberian Peninsula (Vasques et al 2012). During 2012, 41 large wildfires (ranging from 511 to 28,879 ha) were recorded in Spain, which burned 135,580 ha in total (representing 63 % of the total forested area burned in that year, a surface 300 % higher than the average of the last decade), primarily affecting many large P. pinaster stands (Ministerio de Agricultura, Alimentación y Medio Ambiente 2014).…”

“…Court-Picon et al 2004;Ganatsas et al 2008;Liu et al 2013;Parker et al 2006). Seed mass is often positively associated with post-fire seedling establishment, growth, and survival (Álvarez et al 2007;Bladé and Vallejo 2008;Escudero et al 2000), but no consensus exists on the relationship between seed mass and germination rates following fire (Escudero et al 2002;Hanley et al 2003;Casal 1995, 2004;Vasques et al 2012). In the case of P. pinaster, heavier and larger seeds are less sensitive to high temperatures and more resistant to fire (Escudero et al 1999(Escudero et al , 2000Casal 1995, 2001) and are, therefore, thought to experience lower mortality during severe fires.…”