To resist or to germinate? The effect of fire on legume seeds in Brazilian subtropical grasslands

Fidelis, Alessandra; Daibes, L. Felipe; Martins, Aline Redondo

doi:10.1590/0102-33062015abb0187

Cited by 26 publications

(17 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A lack of fire-stimulated germination has also been shown for fire-prone Brazilian subtropical grasslands, the Argentinean Chaco and the Chilean matorral (Overbeck et al, 2006;Jaureguiberry and Díaz, 2015;Fidelis et al, 2016;Gómez-González et al, 2017). Irrespective of germination, seed traits were important predictors of seed mortality under the hottest treatment.…”

Section: Discussionmentioning

confidence: 87%

Fire and legume germination in a tropical savanna: ecological and historical factors

et al. 2019

Self Cite

View full text Add to dashboard Cite

Background and Aims In many flammable ecosystems, physically dormant seeds show dormancy-break patterns tied to fire, but the link between heat shock and germination in the tropical savannas of Africa and South America remains controversial. Seed heat tolerance is important, preventing seed mortality during fire passage, and is usually predicted by seed traits. This study investigated the role of fire frequency (ecological effects) and seed traits through phylogenetic comparison (historical effects), in determining post-fire germination and seed mortality in legume species of the Cerrado, a tropical savanna–forest mosaic. Methods Seeds of 46 legume species were collected from three vegetation types (grassy savannas, woody savannas and forests) with different fire frequencies. Heat shock experiments (100 °C for 1 min; 100 °C for 3 min; 200 °C for 1 min) were then performed, followed by germination and seed viability tests. Principal component analysis, generalized linear mixed models and phylogenetic comparisons were used in data analyses. Key Results Heat shocks had little effect on germination, but seed mortality was variable across treatments and species. Seed mortality was lowest under the 100 °C 1 min treatment, and significantly higher under 100 °C 3 min and 200 °C 1 min; larger seed mass decreased seed mortality, especially at 200 °C. Tree species in Detarioideae had the largest seeds and were unaffected by heat. Small-seeded species (mostly shrubs from grassy savannas) were relatively sensitive to the hottest treatment. Nevertheless, the presence of physical dormancy helped to avoid seed mortality in small-seeded species under the hottest treatment. Conclusions Physical dormancy-break is not tied to fire in the Cerrado mosaic. Heat tolerance appears in both forest and savanna species and is predicted by seed traits (seed mass and physical dormancy), which might have helped forest lineages to colonize the savannas. The results show seed fire responses are better explained by historical than ecological factors in the Cerrado, contrasting with different fire-prone ecosystems throughout the world.

show abstract

Section: Discussionmentioning

confidence: 87%

Fire and legume germination in a tropical savanna: ecological and historical factors

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…() and Van Klinken & Goulier () for four tropical legume species in Australia, and by Fidelis et al . () for some tropical legume species in Brazil, where dry heat (even at 150 °C) did not break PY. Erickson et al .…”

Section: Discussionmentioning

confidence: 94%

Sensitivity cycling in physically dormant seeds of the Neotropical tree Senna multijuga (Fabaceae)

Rodrigues-Junior

Baskin

et al. 2018

Plant Biol J

View full text Add to dashboard Cite

Cycling of sensitivity to physical dormancy (PY) break has been documented in herbaceous species. However, it has not been reported in tree seeds, nor has the effect of seed size on sensitivity to PY-breaking been evaluated in any species. Thus, the aims of this study were to investigate how PY is broken in seeds of the tropical legume tree Senna multijuga, if seeds exhibit sensitivity cycling and if seed size affects induction into sensitivity. Dormancy and germination were evaluated in intact and scarified seeds from two collections of S. multijuga. The effects of temperature, moisture and seed size on induction of sensitivity to dormancy-breaking were assessed, and seasonal changes in germination and persistence of buried seeds were determined. Reversal of sensitivity was also investigated. Fresh seeds were insensitive to dormancy break at wet-high temperatures, and an increase in sensitivity occurred in buried seeds after they experienced low temperatures during winter (dry season). Temperatures ≤20 °C increased sensitivity, whereas temperatures ≥30 °C decreased it regardless of moisture conditions. Dormancy was broken in sensitive seeds by incubating them at 35 °C. Sensitivity could be reversed, and large seeds were more sensitive than small seeds to sensitivity induction. Seeds of S. multijuga exhibit sensitivity cycling to PY-breaking. Seeds become sensitive during winter and can germinate with the onset of the spring-summer rainy season in Brazil. Small seeds are slower to become sensitive than large ones, and this may be a mechanism by which germination is spread over time. Sensitive seeds that fail to germinate become insensitive during exposure to drought during summer. This is the first report of sensitivity cycling in a tree species.

show abstract

“…Reproduction from seed clearly plays a role in old-growth grassland plant population dynamics (Keeley & Fotheringham, 2000;Medina & Fernandes, 2007), but few old-growth tropical grassland plant populations rely on persistent seed banks for post-fire regeneration (Duvigneaud & Denaeyer-De Smet, 1963;Overbeck et al, 2005;Kolbek & Alves, 2008;Lamont & Downes, 2011;Fidelis et al, 2012). Instead, many species flower profusely (Conceição et al, 2013;Fidelis & Blanco, 2014) after resprouting from bud banks, and then produce seeds, most of which never establish (Overbeck et al, 2006;Dayamba et al, 2008Dayamba et al, , 2010Neves & Conceição, 2010;Fichino et al, 2012Fichino et al, , 2016Le Stradic et al, 2015;Delhaye et al, 2016;Fidelis, Daibes & Martins, 2016).…”

Section: Resilience (1) Endogenous Disturbances and Plant Resproumentioning

confidence: 99%

Resilience and restoration of tropical and subtropical grasslands, savannas, and grassy woodlands

et al. 2018

Self Cite

View full text Add to dashboard Cite

Despite growing recognition of the conservation values of grassy biomes, our understanding of how to maintain and restore biodiverse tropical grasslands (including savannas and open‐canopy grassy woodlands) remains limited. To incorporate grasslands into large‐scale restoration efforts, we synthesised existing ecological knowledge of tropical grassland resilience and approaches to plant community restoration. Tropical grassland plant communities are resilient to, and often dependent on, the endogenous disturbances with which they evolved – frequent fires and native megafaunal herbivory. In stark contrast, tropical grasslands are extremely vulnerable to human‐caused exogenous disturbances, particularly those that alter soils and destroy belowground biomass (e.g. tillage agriculture, surface mining); tropical grassland restoration after severe soil disturbances is expensive and rarely achieves management targets. Where grasslands have been degraded by altered disturbance regimes (e.g. fire exclusion), exotic plant invasions, or afforestation, restoration efforts can recreate vegetation structure (i.e. historical tree density and herbaceous ground cover), but species‐diverse plant communities, including endemic species, are slow to recover. Complicating plant‐community restoration efforts, many tropical grassland species, particularly those that invest in underground storage organs, are difficult to propagate and re‐establish. To guide restoration decisions, we draw on the old‐growth grassland concept, the novel ecosystem concept, and theory regarding tree cover along resource gradients in savannas to propose a conceptual framework that classifies tropical grasslands into three broad ecosystem states. These states are: (1) old‐growth grasslands (i.e. ancient, biodiverse grassy ecosystems), where management should focus on the maintenance of disturbance regimes; (2) hybrid grasslands, where restoration should emphasise a return towards the old‐growth state; and (3) novel ecosystems, where the magnitude of environmental change (i.e. a shift to an alternative ecosystem state) or the socioecological context preclude a return to historical conditions.

show abstract

To resist or to germinate? The effect of fire on legume seeds in Brazilian subtropical grasslands

Cited by 26 publications

References 39 publications

Fire and legume germination in a tropical savanna: ecological and historical factors

Fire and legume germination in a tropical savanna: ecological and historical factors

Sensitivity cycling in physically dormant seeds of the Neotropical tree Senna multijuga (Fabaceae)

Resilience and restoration of tropical and subtropical grasslands, savannas, and grassy woodlands

Contact Info

Product

Resources

About