SPROUTING SUCCESS OF SHRUBS AFTER FIRE - HEIGHT DEPENDENT RELATIONSHIPS FOR DIFFERENT STRATEGIES

The sprouting success of co-occurring populations of shrub species in a temperate woodland of semi-arid Australia was investigated and relat ed to population survival strategies. Straw was added to 21 x 15 m plo ts in the woodland, burnt and the pre-fire characteristics of shrubs w ere used to determine the basis for sprouting success. Species differe d widely (4-94%) in sprouting success; a high percentage of establishe d seedlings of all species were killed by lire but survival increased with height reaching a maximum at 25-60 cm (depending on the species). Thickness of bark at stem bases increased with height growth but spro uting success was not related to bark thickness; sprouting success of shrubs at similar thickness varied greatly between species. All specie s were able to initiate sprouts after cutting through their basal stem s, so lack of active meristems was not a limitation. Species differed in the height at which shrubs began flowering but this was always afte r maximum sprouting success was reached. It is proposed that differenc es between individual shrubs in supply of nutrients, carbohydrates, an d/or water to activated meristems would account for patterns of inter- and intra-specific sprouting success. The data are consistent with re cognised fin survival strategies. 'Sprouters', the species relying mor e on sprouting than recruitment for population persistence, maintained maximum sprouting success with height growth and gained sprouting abi lity along stems once they reached Im in height. In contrast, 'non-spr outers', the species largely relying on recruitment from seed to maint ain populations, were either not able to sprout after seedling establi shment or steadily lost the ability to maintain sprouts with growth be yond 60 cm and did not develop axillary buds along stems at any height .