Dynamics of resprouting in the lignotuberous shrub Banksia oblongifolia

Abstract

The resprouting response of different sized Banksia oblongifolia lignotubers (genets) was followed in two field experiments. In the first, the density and speed of resprouting. and the growth in length of the leading shoot from each lignotuber in response to fire and to the time elapsed since the last fire was monitored for 18 months after fire and clipping treatments. In the second, sizes of bud banks were estimated by repeatedly clipping new shoots from individual lignotubers.Density of resprouting (shoots dm^-lignotuber) decreased with increasinglignotuber size, and the length of the leading shoot increased. The direct effect of fire was to reduce shoot density by about 75%. The speed of resprouting (time taken by a cohort of shoots to reach 50% of their peak density) was similar after fire and clipping, but leading shoots grew significantly longer after fire. The elapsed time since lignotubers were last burnt did not influence their density of resprouting, but it did influence the speed of resprouting. Shoots from clipped lignotubers that had burnt 3 years earlier took about 90 days to each 50% of their peak density while shoots on lignotubers las! burnt 5 and 17 years earlier took about 40 days. Death of shoots was unrelated to crowding in any stand. More lignolubersfrom the oldest unbitrnt stand were grazed by herbivores.The number of buds converted into shoots after successive clippings was surprisingly small: for most lignotubers this reserve was less than three times the size of their standing crop of •Present address:

Early Lignotuber Formation in Banksia—Investigations into the Anatomy of the Cotyledonary Node of TwoBanksia (Proteaceae) Species

“…This latter usage of the term`lignotuber' describes the pronounced woody thickening which is often observed at the base of the stem in B. serrata, even from a very early stage (Mibus, 1998). This, however, is unlike the extensive subterranean lignotubers of B. oblongifolia (Zammit, 1988), or the lignotuberous trait observed in B. menziesii. This suggests that the term`lignotuber' is loosely used to describe a combination of macro features (woody swellings at the plant base; latent buds; resprouting) that may be morphologically dierent and substantially dierent from one another with respect to their ontological origins.…”

“…In lignotubers with concealed bud morphology, which are usually found in plants from xeric environments, the cotyledonary node and upper hypocotyl increase in size and bud number, forming large, resprouting structures at ground level (e.g. B. menziesii), or extensive subterranean structures found in other lignotuberous taxa, such as Banksia oblongifolia (Zammit, 1988) and Eucalyptus gummifera (Mullette, 1978). In Banksia species with lignotubers comprising visible super®cial masses of buds, usually from temperate, high rainfall climates, the bud structures are located at ground level (e.g.…”

Satellite Evidence of Decreasing Resilience in Mediterranean Plant Communities after Recurrent Wildfires

“…Decreasing underground reserves may explain this declining response (Canadell and Ló-pez-Soria 1998). Although bud bank depletion after frequent disturbances has been reported (Zammit 1998), further research is needed to investigate if this reduction is effective at the time scale in which fire recurrence occurs in our area. However, long-lived seeder species, such as Pinus halepensis, which is dominant in the region and often shows a very good regeneration after fire, may be sensitive to recurrent fires that limit seed storage (Thanos and Daskalakou 2000).…”

Underground starch storage in Erica species of the Cape Floristic Region – differences between seeders and resprouters

“…†Present address : Department of Botany, University of Western Australia, Nedlands 6709, Western Australia. and a store of carbon as a potential source of energy to support regrowth (Zammit, 1988 ;Lloret & Lo! pez-Soria, 1993 ;.…”