Light intensity triggers different germination responses to fire-related cues in temperate grassland species Luis López-Mársico & Lucía Farías-Moreira & Felipe Lezama & Alice Altesor & Claudia Rodríguez Received: 30 June 2018 /Accepted: 4 February 2019 # Institute of Botany, Czech Academy of Sciences 2019 Abstract Fire is a widespread disturbance that affects plant individuals and populations. In fire-prone environ- ments, such as Mediterranean-type ecosystems, many species are stimulated to germinate by fire-related cues, for example heat and smoke. However, little is known about the effect of fire on seed germination of species from herbaceous communities like temperate grass- lands. In this study we assessed the germination re- sponse to direct (heat shock and smoke) and indirect (light intensity) fire-related cues of five herbaceous and one shrubby species that occur in natural grasslands of eastern Uruguay. All species are native and belong to the Poaceae (2 species) and Asteraceae (4 species) families. Seeds were subjected to smoke and heat shock treat- ments (50°C, 100°C) under two light intensities (high- light and low-light). We found that direct fire-related cues did not stimulate germination in any of the species studied. Most of the species showed a reduced percent- age of germination or a delayed mean germination time, relative to the control treatment, when exposed to heat shock at 100°C or smoke. However, the seeds survived the exposure to high temperatures, indicating that they can tolerate a fire event. Light was found to be a key germination cue. Treated seeds responded to fire-related cues mainly when we simulated the high-light environ- ment after fire. Our results contribute to the growing body of evidence that many species of South American grasslands do not rely on recruitment by seeds after a fire event, but rather on the ability to resprout by means of subterranean or protected basal buds. Keywords heat shock . smoke . high light conditions . seed germination . prescribed burning . Uruguay Introduction Fire is a widespread disturbance that affects plant indi- viduals and populations. After a burning event, plants may persist by vegetative regeneration (‘resprouters’), by seed recruitment (‘seeders’), or by combining both strategies (Pausas et al. 2004; Paula and Pausas 2008; Le Stradic et al. 2015; Zupo et al. 2016). Many grassland taxa are hemicryptophytes or geophytes (Raunkiaer 1934) and bear their regenerative buds at or below the soil surface. On the other hand, seeders rely on regen- eration from seeds for post-fire recovery (Pausas et al. 2004; Paula and Pausas 2008). Typically, seeders allo- cate most of their resources to aboveground growth and establish rapidly after fires (Verdú 2000). To achieve successful establishment, seeds must sur- vive during fire, and germination may be stimulated by some fire-related cues, such as heat shock and smoke (Keeley and Fortheringham 2000; Dayamba et al. 2008; Folia Geobot https://doi.org/10.1007/s12224-019-09336-5 L. López-Mársico (*) : L. Farías-Moreira : A. Altesor : C. Rodríguez Grupo de Ecología de Pastizales, Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay e-mail: luislopez@fcien.edu.uy F. Lezama Departamento de Sistemas Ambientales, Facultad de Agronomía, Universidad de la República, Garzón 780, 12900 Montevideo, Uruguay