RETRACTED ARTICLE: Fire and summer temperatures work together breaking physical seed dormancy

Abstract

Fire and high summer soil temperatures can break physical seed dormancy in Mediterranean fire-prone ecosystems. Their independent effect is somewhat recognized but both factors may act together with a synergistic effect yet unknown. This study aims to determine the isolated and combined effects of fire and summer temperatures on the release of physical seed dormancy in Cistaceae species. Fire and summer temperature treatments were applied in a factorial experiment to seeds of 12 species of Cistaceae. Seeds previously exposed or not to a heat shock (fire simulation) were kept for 1 or 2 months at constant or alternating temperatures (summer temperatures simulation). Additionally, I compared the effect of exposing the seeds to a heat shock before or after they had been subjected to the summer temperatures. Heat shock increased germination of all species, but summer temperatures produced different results. When seeds were exposed to summer temperatures after heat shock, germination decreased. This negative effect disappeared when heat shock was simulated at the end of the summer temperatures. Fire and summer temperatures modulate timing of germination in Cistaceae with a joint control on post-fire regeneration. Cycling of sensitivity to physical dormancy release may be the mechanism to explain this fine-tuning, which would ensure germination when environmental conditions are suitable for growth. These results contribute to our understanding of vegetation dynamics and postfire regeneration in Mediterranean ecosystems.

Influence of the Storage of Cistus ladanifer L. Bales from Mechanised Harvesting on the Essential Oil Yield and Qualitative Composition

“…In the Mediterranean region, it has dominant nature, with adaptation to extreme environmental factors such as the ability to survive in low hydric and high solar exposition conditions [3][4][5]. Moreover, it is a pyrophyte plant [6,7] and often forms dense scrub communities that produce phytotoxic compounds (likely allelopathic) that may have inhibitory effects on the herbaceous understorey [3,[8][9][10][11]. Therefore, Cistus ladanifer can eliminate competition and become a colonising species.…”

“…W is the main producer [15], but there is great potentia dura, Castilla La Mancha and Castilla y León (Wester Wildland fire is one of the major disturbance factors in Mediterranean ecosystems [7] and shrub clearings, together with other actions, have been shown to be an effective method to control fires and improve the land management of abandoned areas [14]. In this sense, and considering that Cistus ladanifer is a fire-prone plant species [6,7], clearings in areas where this plant is dominant and form dense and continuous shrubs could prevent fires and generate substantial amounts of sustainable raw material to obtain high added value products and bioenergy within the biorefinery concept.…”

Fire and seed maturity drive the viability, dormancy, and germination of two invasive species: Acacia longifolia (Andrews) Willd. and Acacia mearnsii De Wild

“…Arán et al (2017) demonstrated in seeds of A. melanoxylon soil bank that not all seeds of soil bank respond to fire; there remains a part of dormant seeds that could break dormancy through other mechanisms, such as scarification by friction with soil particles or the expansion and contraction caused by summer temperatures. This loss of dormancy can be added to that caused by fire in some species (Santana et al 2010(Santana et al , 2013Luna 2020), generating extensive germination in mature seeds. Also, heat was the only fire factor studied in this paper that produced significant effects on the germination of A. longifolia and A. mearnsii.…”

“…Fire also plays an important role shaping plant communities in many ways, driving their diversity (He et al 2019), shaping plant traits (Keeley et al 2011), creating open gaps, and modifying the dormancy and germination of many species (Auld and O'Connell 1991;Reyes and Casal 2008). Fire and summer temperatures work together breaking seed dormancy (Luna 2020), opening the possibility for new species to establish in natural communities or even become dominant. Since germination is the most critical stage in the life cycle of many plants, the influence of fire on seed dormancy breaking and germination may be decisive for the establishment of native (Reyes et al 2000) and invasive alien species (IAS) (Arán et al 2017).…”

“…Viability and dormancy of some species either remain constant for many years or vary during the first year of maturation (Orscheg and Enright 2011). Seed maturation can interact with fire and/or with summer temperatures (Luna 2020) by modulating the dormancy and germination response to fire (Reyes and Casal 2001;Ooi 2010). Specifically, Arán et al (2017) found that 2-year-old Acacia melanoxylon R. Br.…”