Fitness and evolution of resprouters in relation to fire

Abstract

There are many ways that plants may recover vegetatively from dieback caused by fires. Compared with fire-killed species, the presence of woody resprouters in fire-prone floras increases with fire frequency, though this is affected by site productivity that may have opposing correlates along different gradients. Population recovery is enhanced by resprouting when fecundity is low and/or seedling recruitment is not guaranteed. There is resource cycling between vegetative growth and storage but no clear trade-off between fecundity and storage, and more attention needs to be given to the role of somatic mutations in reducing fecundity. Seven fitness benefits of post-fire resprouting are noted that centre around the rapid return to adult growth rates and early flowering and seed set without the risks of recruitment failure. The extent of resprouting at the individual, population, and species levels varies greatly but it is under genetic control. Recent studies on the evolution of resprouting in fire-prone systems have shown that types of resprouting (clonality, rootstocks, epicormic bud strands) are derived from surrounding parent lineages lacking these traits and confined to nonfire-prone environments. The oldest lineages with firerelated resprouting date to at least 61 million years ago, indicating that seed plants have had a long evolutionary relationship with fire. Various genetic mechanisms, including beneficial somatic mutations, have been invoked to explain how speciation of resprouters may keep pace with non-sprouters.

Fire-mediated disruptive selection can explain the reseeder–resprouter dichotomy in Mediterranean-type vegetation

“…These results are consistent with field observation showing that reseeders are more frequent at low fire frequencies whereas resprouters are dominant at higher fire frequencies (Le Maitre and Midgley 1992;Ojeda 1998;Vlok and Yeaton 2000;Lamont et al 2011). Our results also confirm earlier work showing that fire can be a strong structuring force in plant communities (Higgins et al 2000a).…”

“…The clear life-history dichotomy and its appearance in many families raise the question of the evolutionary origin of this dichotomy. Apparently, the trait has been evolutionary labile and repeatedly subject to disruptive selection (Lamont et al 2011). For example, in the protea genus Leucadendron, the two fire-response strategies are not phylogenetically clustered, suggesting multiple switches between the two strategies within this single genus alone (Barker et al 2004).…”

“…Later in post-fire succession, reseeders likely incur lower costs of investing in and maintaining carbon-rich defensive structures such as bark, buds (particularly basal buds that are well insulated) and storage tissues (particularly lignotubers) required to support post-fire shoot growth (Pausas et al 2004;Pratt et al 2012). Even though the generality of this trade-off is not well established (Bond and Midgley 2003), there is evidence that seedlings of reseeders tend to grow faster than seedlings of resprouters (Pausas et al 2004;Lamont et al 2011), and the latter also tend to show slower shoot development (associated with greater root development tied to drought avoidance; Pausas et al 2004). In the fynbos and kongwan, which experience more pronounced summer drought than other Mediterraneantype regions, reseeders appear to have higher seedling survival than resprouters during the summer drought (Ojeda et al 2005;Keeley et al 2012).…”

“…One of the determinants of this diversity is thought to be the occurrence of fire (Cowling 1987;Linder 2003;Barraclough 2006;Lamont et al 2011), which has an intermediate frequency in relation to global ecosystems (return interval of roughly 7-25 years, compared to century time scale in forests and annual to biennial time scale in grasslands and savannas). The dry summer season when fires naturally happen are followed by predictably wet winters, particularly in the west where diversity is greatest (Cowling 1992).…”

Comparison of translocation methods to conserve metallophyte communities in the Southeastern D.R. Congo

“…Cu-Co communities are dominated by perennial species which have evolved to resprout after fire and have a low tendency for seed production and seed bank accumulation (Overbeck and Pfadenhauer 2007a;Fidelis et al 2010;Veldman et al 2015). Moreover, it has been shown that resprouting species generally have low fecundity in comparison to non-sprouting species (Lamont and Wiens 2003;Lamont et al 2011). In both communities, we observed uneven emergence from seed bank which significantly contributed to the lack of similarity of spreading topsoil to reference ecosystems after two years as illustrated by both HAI and CSII.…”