Burning grasses, poor seeds: post-fire reproduction of early-flowering Neotropical savanna grasses produces low-quality seeds

Fontenele, Hudson G. V.; Cruz-Lima, Letícia F. S.; Pacheco-Filho, José L.; Miranda, Heloísa S.

doi:10.1007/s11258-020-01080-7

Cited by 17 publications

(19 citation statements)

References 41 publications

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“…The ability of germinants to reach the surface falls linearly to be negligible once this same depth is reached (Fig. 4D, E), and is usually negatively related to seed size (Fontenele et al ., 2020; Tangney et al ., 2020). The depth to which species are buried is a function of time, seed characteristics (size, surface texture, shape), soil properties (litter thickness, soil texture and density, which also affect heat transfer), and the extent to which seeds are buried by dispersal agents (Saatkamp, Pochlod & Lawrence, 2014; Fig.…”

Section: Fire As a Dormancy‐release Mechanismmentioning

confidence: 99%

Fire‐released seed dormancy ‐ a global synthesis

Pausas

Lamont

2022

Biological Reviews

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Seed dormancy varies greatly between species, clades, communities, and regions. We propose that fireprone ecosystems create ideal conditions for the selection of seed dormancy as fire provides a mechanism for dormancy release and postfire conditions are optimal for germination. Thus, fire-released seed dormancy should vary in type and abundance under different fire regimes. To test these predictions, we compiled data from a wide range of fire-related germination experiments for species in different ecosystems across the globe. We identified four dormancy syndromes: heat-released (physical) dormancy, smoke-released (physiological) dormancy, non-fire-released dormancy, and non-dormancy. In fireprone ecosystems, fire, in the form of heat and/or chemical by-products (collectively termed 'smoke'), are the predominant stimuli for dormancy release and subsequent germination, with climate (cold or warm stratification) and light sometimes playing important secondary roles. Fire (heat or smoke)-released dormancy is best expressed where woody vegetation is dense and fires are intense, i.e. in crown-fire ecosystems. In such environments, seed dormancy allows shade-intolerant species to take advantage of vegetation gaps created by fire and synchronize germination with optimal recruitment conditions. In grassy fireprone ecosystems (e.g. savannas), where fires are less intense but more frequent, seed dormancy is less common and dormancy release is often not directly related to fire (non-fire-released dormancy). Rates of germination, whether controls or postfire, are twice as fast in savannas than in mediterranean ecosystems. Fire-released dormancy is rare to absent in arid ecosystems and rainforests. The seeds of many species with fire-released dormancy also possess elaiosomes that promote ant dispersal. Burial by ants increases insulation of seeds from fires and places them in a suitable location for fire-released dormancy. The distribution of these dormancy syndromes across seed plants is not randomcertain dormancy types are associated with particular lineages (phylogenetic conservatism). Heat-released dormancy can be traced back to fireprone floras in the 'fiery' mid-Cretaceous, followed by smoke-released dormancy, with loss of fire-related dormancy among recent events associated with the advent of open savannas and non-fireprone habitats. Anthropogenic influences are now modifying dormancy-release mechanisms, usually decreasing the role of fire as exaptive effects. We conclude that contrasting fire regimes are a key driver of the evolution and maintenance of diverse seed dormancy types in many of the world's natural ecosystems.

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Section: Fire As a Dormancy‐release Mechanismmentioning

confidence: 99%

Fire‐released seed dormancy ‐ a global synthesis

Pausas

Lamont

2022

Biological Reviews

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“…About 25% of Cerrado grass species exhibit post‐flowering fire dependency (Fidelis & Zirondi, 2021). Several factors can trigger flowering, such as the removal of above‐ground biomass, which would explain the flowering of grasses in firebreaks that used mechanical removal (as observed by Fontenele et al, 2020). However, Fidelis and Blanco (2014) found that twice as many species flowered in burned than in mowed plots, and so other factors might also be related to post‐fire flowering, such as increased soil nutrients and removal of the litter layer (Curtis & Partch, 1948, 1950; Daubenmire, 1968; Kucera & Ehrenreich, 1962; Pyke, 2017), increased micro‐habitat temperatures and light availability (Fidelis & Blanco, 2014), as well as the direct effect of heat on buds (Curtis & Partch, 1950).…”

Section: Discussionmentioning

confidence: 99%

Fire stimulates grass flowering in the Cerrado independent of season

Fidelis

Zirondi

Rossatto

et al. 2022

J Vegetation Science

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Fire regimes play an important role in the flowering of several plant species. Frequent fires may have a positive impact by reducing dormancy levels, while fire exclusion may lead to decreased flower abundance due to competition (Coates et al., 2006). Post-fire flowering is a fire-adaptive trait that has been primarily described for Mediterranean-climate vegetation (Lamont & Downes, 2011). However, it is present in several families in different flammable ecosystems, although mostly described among monocots, such as orchids and grasses (Lamont & Downes, 2011). Grasses are less studied in this regard and may have their flowering affected by fire (Monasterio & Sarmiento, 1976), although it is not clear how fire stimulates grass flowering and how interaction between fire season (wet-and dry-season fires) and history affect grass phenology.Post-fire flowering may occur through the direct effect of heat on

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“…Up to 80% of T. spicatus seeds can be empty (i.e., embryoless; Zanetti et al, 2020), clarifying its low germination and emergence rates in field conditions (Pellizzaro et al, 2017). Poor seeds and strong dormancy are common in Cerrado grasses (Le Stradic et al, 2015;Fontenele et al, 2020). It is, therefore, fundamental to improve seed quality control and enhancement techniques to establish key ground-layer species when direct seeding is chosen as the main restoration method (Buisson et al, 2021).…”

Section: Cerrado's Major Seed Suppliers Have Unique and Complementary...mentioning

confidence: 99%

Toward diverse seed sourcing to upscale ecological restoration in the Brazilian Cerrado

et al. 2022

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Seed markets are vital to scaling up ecosystem restoration in the Brazilian Cerrado, home of the world’s most species-rich grasslands and savannas. We compiled lists of species traded by four major Cerrado seed supply systems to investigate the representativeness of the species currently available for seed-based restoration. We also identified whether dominant ground-layer species are being sourced for seed production. Seeds from 263 Cerrado species can be purchased for restoration, of which 68% are trees, particularly legumes (24%). 63% of the traded species were found in only one seed supply system. The five most dominant graminoids of the Cerrado ground layer were available for sale, but two additional species uncommon in old-growth areas represented 44% of the sales of a key seed trader in Central Brazil. The expansion of Cerrado seed supply systems should be supported to further increase the number of species on the market. Sourcing seeds from a diversity of herbaceous species is central to facilitating the restoration of species-rich grasslands and savannas in the Cerrado. Recovering the diversity and functioning of old-growth open ecosystems through seeds will depend on increasing the supply and demand for species typical of Cerrado’s ground layer.

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Burning grasses, poor seeds: post-fire reproduction of early-flowering Neotropical savanna grasses produces low-quality seeds

Cited by 17 publications

References 41 publications

Fire‐released seed dormancy ‐ a global synthesis

Fire‐released seed dormancy ‐ a global synthesis

Fire stimulates grass flowering in the Cerrado independent of season

Toward diverse seed sourcing to upscale ecological restoration in the Brazilian Cerrado

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