Archive

Archive for August, 2019

Fire, grasses, and buds

August 26th, 2019 No comments

The traditional view is that C4 grasses are more efficient in open, dry, and warm habitats because they are able to fix more carbon under warm and sunny environments than C3 grasses. However, these habitats are also likely to be fire-prone, and thus their survival may depend on the bud protection mechanisms. Using data from a previous postfire resprouting experiment [1] we show that plant mortality and resprouting response are better explained by the location of the buds than by the photosynthesis pathway (C3 vs C4) [2]. Grasses with aerial buds (stolons) are more exposed to fire and have higher mortality and less resprouting than those with belowground buds (rhizomes); those with buds in the root-crown show an intermediate response (Fig. 1 below). This suggests that carbon reserves are not the only limiting factor for resprouting. The first requirement for initial resprouting is the survival of the bud bank, which depends on the degree of bud protection [3]. Once the initial resprouting occurs, the carbon reserves and the new photo-assimilates should determine the resprouting vigour [4]. In conclusion, to fully understand the variability in postfire resprouting in grasses we need to consider the location and the degree of protection of the bud bank [3]. The bud bank could also had a role, together with C4 photosynthesis, in the massive C4 grass expansion during the Late Miocene (3-8 Ma).

Fig. 1. Mean proportion of postfire tillers in relation to prefire tillers in Australian grasses across treatments aggregated by the species that have different bud locations (stolons, crown, rhizomes), and by the different photosynthetic pathway (C3, C4). From [2].

References

[1] Moore NA, Camac JS, Morgan JW. 2019. Effects of drought and fire on resprouting capacity of 52 temperate Australian perennial native grasses. New Phytologist 221:1424–1433.

[2] Pausas J.G. & Paula S. 2019. Grasses and fire: the importance of hiding buds. New Phytologist [doi | pdf]

[3] Pausas J.G., Lamont B.B., Paula S., Appezzato-da-Glória B. & Fidelis A. 2018. Unearthing belowground bud banks in fire-prone ecosystems. New Phytologist 217: 1435–1448. [doi | pdf | suppl. | BBB database]

[4] Moreira B., Tormo J, Pausas J.G. 2012. To resprout or not to resprout: factors driving intraspecific variability in resprouting. Oikos 121: 1577-1584. [doi | pdf]