Resilience of a high-conservation-value, semi-arid grassland on fertile clay soils to burning, mowing and ploughing
-
Published source details
Lewis T., Reid N., Clarke P.J. & Whalley R.D.B. (2010) Resilience of a high-conservation-value, semi-arid grassland on fertile clay soils to burning, mowing and ploughing. Austral Ecology, 35, 464-481.
Published source details Lewis T., Reid N., Clarke P.J. & Whalley R.D.B. (2010) Resilience of a high-conservation-value, semi-arid grassland on fertile clay soils to burning, mowing and ploughing. Austral Ecology, 35, 464-481.
Summary
To help advise management of grassland dominated by native perennial Mitchell grass Astreblaelymoides and bluegrass Dichanthium sericeum at Kirramingly Nature Reserve (29°43′40.6″S, 149°40′40.1″E; 1,296 ha) in New South Wales (Australia), experiments were undertaken to determine the impact of fire, kangaroo grazing, mowing and disc-ploughing on plant species richness and composition.
In 1996 when the area became a nature reserve, domestic livestock were removed. In 2002 within a homogeneous area (dominated by Mitchell grass and bluegrass with scattered needle bush Vachellia farnesiana) 18 (200 x 200 m) plots were established, each randomly assigned to one of three treatments: control, spring (September) or autumn (May) burn. Within each plot, vegetation was recorded in two permanent quadrats at intervals over 2-years. Kangaroo grazing was prevented by fencing (exclusion) of some areas in September 2002 (immediately after spring burning and 5 months after autumn burning). Kangaroo grazing activity was assessed by dung pellet counts.
To separate burn plots and to prevent fire from spreading, strips were disc-ploughed in April-May 2002, removing above-ground plant material. To determine the effect of this, quadrats were established in which vegetation was recorded prior to and after (1 and 2 years later) treatment.
Mowing experiments (cutting in September 2002, and April 2003 when cut twice) were also under taken (cutting once or twice to 10 cm height; once or twice to 30 cm; and not an unmown control).
In the experiments, 104 plant taxa were recorded (87% native, 13% introduced). Prior to treatments in autumn 2002, species richness varied from 30 to 45 species per quadrat.
Species composition varied greatly between sampling times, being correlated with rainfall which had a far greater influence than any treatment effect. In the burn plots, species richness and composition recovered more rapidly after spring than autumn burning, but were similar to control sites within 12 months of burning; likewise mown plots. Two burns (separated by 3 years) and post-fire kangaroo grazing had only minor influence (negligible reduction in species richness). Disc ploughing likewise caused only a small reduction in native richness.
Plants recovery after treatment was rapid (within 12 moths) due to the high proportion of perennial species present able to resprout. There appears to be little conservation benefit from fire, mowing or disc-ploughing of these semi-arid grasslands.
)_2023.JPG)
