The tortoise and the hare? Post-fire regeneration in mixed Eucalyptus - Callitris forest

Abstract

Abstract. Seedling regeneration after a high intensity wildfire was assessed in a mixed forest dominated by Eucalyptus species and Callitris endlicheri (Parl.) F.M. Bailey. Patterns were compared against the 'slow seedling' or 'tortoise-and-hare' theory of competitive interactions between gymnosperms and angiosperms. Browsing effects were documented using fenced plots, and seedling density, mortality and height were assessed over 6 years, from 2004-10. Consistent with expectations, Eucalyptus seedlings grew faster than Callitris seedlings in most situations. Callitris seedlings grew faster and produced seed cones sooner in plots with fewer Eucalyptus seedlings compared with plots with dense Eucalyptus seedlings. The local growth rates of Callitris seedlings were not associated with long-term site suitability for Callitris, as many plots with diminutive Callitris seedlings and dense Eucalyptus seedlings were dominated by Callitris trees before the 2003 fire. Contrary to expectations, few Callitris seedlings died during the 6-year period, so competition during the regeneration phase did not regulate co-existence. Strong drought tolerance and the ability to persist in dense, unthinned stands may enable Callitris to persist beneath dense Eucalyptus regeneration. Nevertheless, Callitris seedlings growing with dense Eucalyptus seedlings have a longer primary juvenile period than seedlings in sites with fewer seedling or adult eucalypts, which places these stands at greater risk of mortality in future fires and greater risk of browsing in the meantime.

Improved simulation of fire–vegetation interactions in the Land surface Processes and eXchanges dynamic global vegetation model (LPX-Mv1)

“…We assess the relationship between bark thickness and stem diameter based on 13 297 measurements from 1364 species (see Supplement for information on the studies these were obtained from). The species were classified into PFTs based on their leaf type, phenology and climate range (Table S1 in the Supplement); in cases where this was not provided by the original data contributors, we used information from trait databases, floras and the literature (e.g Kauffman, 1991;Greene et al, 1999;Bellingham and Sparrow, 2000;Williams, 2000;Bond and Midgley, 2001;Del Tredici, 2001;Pausas et al, 2004;Paula et al, 2009;Lunt et al, 2011). The climate range was based on the overall range of the species, not derived from the climate of the sites.…”

“…Aerial resprouting is found in both tropical and temperate trees, regardless of phenology (Kaufmann and Hartmann, 1991;Bellingham and Sparrow, 2000;Williams, 2000;Bond and Midgley, 2001;Del Tredici, 2001;Paula et al, 2009). It is very uncommon in gymnosperms (Del Tredici, 2001;Paula et al, 2009;Lunt et al, 2011) and does not seem to be promoted by fire in deciduous broadleaf trees in boreal climates (Greene et al, 1999). We therefore introduced resprouting variants of four PFTs in LPX-Mv1: tropical broadleaf evergreen tree (TBE), tropical broadleaf deciduous tree (TBD), temperate broadleaf evergreen tree (tBE), and temperate broadleaf deciduous tree (tBD).…”

Two climate‐sensitive tree‐ring chronologies from Arnhem Land, monsoonal Australia

“…Individuals of the species growing in monospecific stands generally reach maturity later than isolated individuals that also have a faster growth rate (Lunt et al . ; Lawes et al . ).…”

The foliar characters in Callitris (Callitroideae, Cupressaceae s. str.) and their evolutionary and ecological significance

“…In a study of C. endlicheri it was considered their strong drought tolerance (Lunt et al. ) which is linked to their reduced leaf morphology and their ability to establish between fires enabled Callitris to survive in competition with eucalypts and under particular fire regimes may lead to its dominance. The reduced leaf morphology and anatomical attributes such as transfusion tissue and mesophyll sclereids along with the development of serotiny in some species and relatively shade tolerant seedlings (Harris and Kirkpatrick ; Lunt et al.…”