PDF 3954.pdf | Request a copy Full text restricted Available under University of Tasmania Standard License.

Abstract

In temperate Australia, sustainability of biodiversity in poorly-reserved woodland remnants
within agricultural landscapes is a priority. Cornerstone species, such as those comprising
the tree overstorey, are essential as a seed source for regeneration and for
microclimate amelioration, soil erosion prevention and habitat provision in woodland ecosystems.
However, trees within many woodland remnants are rapidly deteriorating in
health. This has been attributed to several causes, including three decades of below average
rainfall in temperate Australia. However, instances where trees are healthy and declining
on either side of a management boundary indicate a key role of management in the
condition of woodland remnants. We investigated the effects of past management on soil
properties and vegetation understorey, and linked these with overstorey tree health across
49 sites within the agricultural Midlands of Tasmania, Australia. Sixty percent of the variation
in overstorey tree health was associated with the cover of native shrubs, litter, moss
and lichen in healthy sites and with cover of exotic pasture species in declining sites. Soil
attributes explained 72% of the variation in tree health, with healthy sites having lower soil
total nitrogen and pH, and higher soil organic carbon. A combination of soil and understorey
vegetation attributes entirely separated healthy, declining and poor sites in a canonical
analysis. Regression tree analysis indicated that grazing history (fencing, grazing frequency
and intensity) was the primary management history factor in separating healthy and poor
sites, whilst patch size, fire frequency and wood gathering were secondary, but significant,
factors. Sites that were only lightly, if at all, grazed, had a fire frequency >10 years, and did
not have coarse woody debris removed were healthy, indicating that the drying and warming
climate of the past three decades is within the bioclimatic envelope of the species
examined.

Item Type:	Article
Authors/Creators:	Davidson, NJ and Close, DC and Battaglia, M and Churchill, K and Ottenschlaeger, M and Watson, T and Bruce, J
Keywords:	Grazing; Fire; Patch size; Eucalyptus; Tree dieback; Tree decline
Journal or Publication Title:	Biological Conservation
Publisher:	Elsevier BV
ISSN:	0006-3207
DOI / ID Number:	https://doi.org/10.1016/j.biocon.2007.07.019
Additional Information:	The definitive version is available at http://www.sciencedirect.com
Item Statistics:	View statistics for this item

Actions (login required)

Item Control Page