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In 1985 and 1989, two studies examined the effects of time since fire, topography and resprouting eucalypts on the composition of understorey species in mallee vegetation at Yathong Nature Reserve, in semi-arid New South Wales. Emphasis was on ephemerals. Species richness was significantly higher at 2.5 years after fire. Species present five years after fire were a subset of those occurring earlier. Twodimensional ordination based on ranked similarity measures of species and analysis of similarities indicated discrete time since fire groups. Short-lived species dominated early groups (< 2.5 years) i.e. Haloragis odontocarpa, Convolvulus erubescens, Sclerolaena parviflora and Solanum coactiliferum. All these species had disappeared at > 5 years. The perennials Triodia scariosa, Amphipogon caricinus and Halgania cyanea, dominated at > 5 years post-fire. Species composition was significantly affected by topographic position (upper, mid, lower dune) but not by mallee eucalypts (under canopy, in gap). Two-dimensional ordination based on ranked similarity measures of species and ANOSIM indicated that upper and lower topographic positions were significantly different. Most common species in upper topographic positions were Haloragis odontocarpa, Bracteantha viscosa and Sclerolaena parviflora and in the lower Stipa scabra, Haloragis odontocarpa and Chenopodium sp. Species richness was not significantly affected by topography or eucalypts (17.45/10m2 +/- 0.16). The number of ephemeral species (10 m-2) was higher in the lower topographic positions (7.87 +/- 0.66) than the upper (4.88 +/- 0.44). There was no significant effect of eucalypts on the number of ephemeral or perennial species.
In Australia, the Proteaceae are a diverse group of plants. They inhabit a wide range of environments, many of which are low in plant resources. They support a wide range of animals and other organisms, and show distinctive patterns of distribution in relation to soils, climate and geological history. These patterns of distribution, relationships with nutrients and other resources, interactions with animals and other organisms and dynamics of populations in Proteaceae are addressed in this review, particularly for the Sydney region.
The Sydney region, with its wide range of environments, offers great opportunities for testing general questions in the ecology of the Proteaceae. For instance, its climate is not mediterranean, unlike the Cape region of South Africa, south-western and southern Australia, where much of the research on plants of Proteaceae growing in infertile habitats has been done.
The diversity and abundance of Proteaceae vary in the Sydney region inversely with fertility of habitats. In the region’s rainforest there are few Proteaceae and their populations are sparse, whereas in heaths in the region, Proteaceae are often diverse and may dominate the canopy. Research in the region has led to an understanding of their various responses to fire, dynamics of their populations in fire-prone landscapes, interactions with animals in pollination and dispersal, and of their breeding systems. This review examines results of this research and shows that ecological research has been uneven in Australian Proteaceae, with little work done on rainforest and alpine Proteaceae.
The review reveals an enormous range of interesting features of the Proteaceae of the Sydney region. It also identifies a large number of questions about ecological and evolutionary processes that are at the cutting edge of our current knowledge. The diversity of taxa of Proteaceae, the range of habitat, soil and climatic zones they occupy, the variety of life-histories (even among populations within species), fire responses, floral morphologies, pollinator types and breeding systems combine to make this family in the region a rich ‘test bed’ for many of these questions.