Fencing remnant native vegetation has become a widespread activity for arresting declines in biodiversity in agricultural landscapes. However, few data are available on the effectiveness of this approach.
In June-July 2000, vegetation and soil surveys were undertaken at 47 sites fenced by Greening Australia for 2 to 4 years in southern NSW. Woodlands sampled were dominated by Yellow Box / Blakely’s Red Gum (Eucalyptus melliodora / E. blakelyi), Grey Box (E. microcarpa) or White Cypress-pine (Callitris glaucophylla). The aim of the study was to investigate the short-term effects of fencing to exclude livestock on dominant tree and shrub recruitment, plant species cover, litter and soil characteristics in remnant grassy woodlands
Fenced and unfenced White box woodlands, with greater tree regen. and perennial grasses in fenced area (right)
Significantly greater tree regeneration occurred in fenced remnant woodland sites, with tree recruitment found in 59% of fenced compared to 13% of unfenced sites.
Fenced sites had significantly greater cover of native perennial grasses, less cover of exotic annual species, and less soil surface compaction.
Where tree regeneration occurred, there was more box seedlings where there was greater perennial grass cover as opposed to exotic annuals, and less recruitment where the overstorey crown cover was dense — this particular applied to Callitris pine woodlands.
Few shrubs recruited in most fenced or unfenced areas.
Reduced grazing can lead to improved soil conditions, providing suitable conditions for native plants (Purple burr-daisy shown) to re-establish
Fencing is an important first step for conserving threatened grassy woodlands, but more active management may be needed to enhance woodland recovery. Activities may include thinning of overstorey trees, revegetation (ie shrubs), weed control and further work to develop appropriate grazing regimes within fenced sites, to promote native biodiversity.
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In 2005/06, these sites were re surveyed (supported by Greening Australia (ACT), NSW DEC, NSW Environmental Trust - Better Bush project) to assess long term changes in fenced woodland sites - results out soon.
Total stock exclusion can lead to problems - fenced site invaded by Horehound