Journal of the Royal Society of New Zealand abstracts
Biodiversity of indigenous tussock grassland sites in Otago,
Canterbury and the central North Island of New Zealand
IV. Vegetation and the effect of disturbance by agricultural
development and fire
P. R. Espie1 and B. I. P. Barratt2
1AgScience, P.O. Box 1475, Dunedin,
New Zealand. pespie@agscience.co.nz
2AgResearch Invermay, Private Bag
50 034, Mosgiel, New Zealand.
Abstract The
effect of disturbance by agricultural development on plant biodiversity
was assessed on a broad development gradient in three major New Zealand
tussock grassland types. We compared undeveloped, semi-developed, and
pastorally developed snow tussock (Chionochloa rigida)
grasslands in Otago; fescue tussock (Festuca novae-zelandiae)
grasslands in Canterbury; and red tussock (C. rubra)
grasslands in the central North Island volcanic plateau. Plant
diversity and structure were measured using height-frequency transects.
The effect of disturbance by spring and summer burning was similarly
assessed in coastal and inland Otago snow tussock grasslands.
Non-metric multidimensional scaling ordination showed agricultural
development had the greatest effect on plant communities, reducing
indigenous plant species diversity and dominance, and increasing
adventive plant species dominance. Spring and summer burning
significantly reduced indigenous plant species diversity in the montane
coastal Otago snow tussock grassland, but spring burning did not
significantly decrease total or indigenous plant diversity in the
inland alpine grassland. For biodiversity conservation in tussock
grasslands it is critical that representative lower altitude areas are
retained, and that tall tussock grasslands should only be burnt when
retaining sufficient moisture to minimise fire impact. The quantitative
determination of the effects of these disturbance factors will assist
further investigation of vegetation-fauna interactions, and tussock
grassland ecosystem studies.
Keywords tussock
grasslands; plant biodiversity; fire; agricultural development;
burning; gradients
R05014: Received 28 November 2005; accepted 16 May 2006;
Online publication date 9 June 2006
Journal of the Royal Society of New Zealand
Volume 36, Number
2, June, 2006, pp 69–82
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