Silviculture and fire effects on understorey flowering in jarrah forest

Abstract

ABSTRACT Long-term forest monitoring undertaken by Forestcheck since 2001 has examined the effects of silvicultural treatment on floral diversity and assemblage composition in the jarrah forest of southwest Western Australia. Both prescribed burns and wildfires have overlain the network of Forestcheck monitoring sites, providing the opportunity to examine fire and silviculture interactions in natural experiments and allowing experimental control of time-since-fire effects on the flora. We report here two opportunistic experiments. First, the early effects of prescribed burns in spring on the flowering of the vascular flora were compared with closely paired sites that were long unburnt. Second, the early effects of a wildfire in summer on the flowering of the vascular flora were compared between silvicultural treatments. Flowering richness tended to be less on burnt grids in the non-peak period in the first two years after fire in one experiment, but there were no differential effects of silviculture on flowering assemblages arising from interaction with wildfires. Flowering assemblages varied from year to year and the extent to which they varied differed between locations but not as a result of silvicultural treatments. We conclude that no special management with respect to plant flowering is required to remedy outcomes of interaction between wildfire and silvicultural treatments. Further information is needed to understand the long-term implications of variability in flowering assemblages and how it affects the reproductive viability of understorey species and their interactions with pollinator networks in the face of a changing climate.