The effect of exotic pasture development on floristic diversity in central Queensland, Australia (original) (raw)

Abstract

Floristic diversity was compared across boundaries where the trees have been cleared in semi-arid brigalow (Acacia harpophylla), gidgee (A. cambagei) and eucalypt (Eucalyptus populnea, E. melanophloia) woodland and forest in central Queensland. The cleared treatments included Exotic pasture (uncultivated, exotic grasses having more than 10% total cover) and Native pasture (uncultivated, not dominated by exotic grasses). An ordination of presence±absence data did not distinguish the¯oristic composition of the uncleared pasture and native pasture treatments, however, these treatment types were¯oristically distinct from the exotic pasture treatment in all three land types. Declines in species richness and diversity were substantial between uncleared and exotic pastures for brigalow and eucalypt lands. Dierences were far less substantial for the same comparison in gidgee lands, and between uncleared and native pasture for all three land types. These trends re¯ected dierences in most perennial lifeform groups and the species that show signi®cant declines are identi®ed. There was no signi®cant relationship between native diversity and the age of clearing. This study draws attention to the negative impacts on plant diversity posed by deliberate and inadvertent spread of exotic perennial grasses in tropical forests and woodlands. #

Key takeaways

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  1. Exotic pasture establishment significantly reduces floristic diversity in brigalow and eucalypt lands.
  2. Native species richness in uncleared pasture is 295% higher than in exotic pasture in brigalow lands.
  3. This study analyzes the impact of tree clearance and exotic pasture on plant diversity in central Queensland.
  4. Over 85% of original brigalow and gidgee lands were cleared by 1995, exacerbating biodiversity loss.
  5. Cenchrus ciliaris (buel grass) is a major invasive species affecting native plant diversity.

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FAQs

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What significant changes occur in floristic diversity due to exotic pasture development?add

The study reveals a substantial decline in native species richness, with averages showing 295% less in exotic than in uncleared brigalow lands.

How does exotic pasture affect native plant species in this region?add

Exotic pastures result in a lower frequency of native plant species, as indicated by the 40% of species collected post-1980 showing a substantial decrease.

What methodologies were used to assess differences in floristic composition?add

Fifty-one sites were sampled using paired plots with 3x3 meter sub-plots to record vascular plant species abundance and cover percentages.

How does time since initial clearance impact species richness?add

The analysis showed no significant correlation between species richness and time since clearance across all land types, indicating stability in surviving native species.

Which environmental factors influence floristic variation in cleared and uncleared plots?add

Non-metric multi-dimensional scaling identified at least three environmental factors affecting floristic differences among the land types studied.