Fencing farm dams increases vegetation cover, water quality and
macroinvertebrate biodiversity
Abstract
In many farming landscapes, aquatic features such as wetlands, creeks
and dams provide water needed for stock and irrigation, while also
acting as habitat for a range of plants and animals. Indeed, some
species threatened by land use change may otherwise be considerably
rarer – or even extinct – in the absence of these habitats. Therefore,
a critical issue for the maintenance of biodiversity in agricultural
landscapes is the extent to which the management of aquatic systems can
help promote the integration of agricultural production and biodiversity
conservation. We completed a snapshot cross-sectional study in southern
New South Wales (south-eastern Australia) to quantify the efficacy of
simple management practices – partial revegetation and stock reduction
via fencing – for improving vegetation structure, water quality, and
macroinvertebrate assemblages. We found that even short-term livestock
exclusion resulted in increased vegetation cover. Relative to dams that
were unfenced, those that had been partially or completely fenced for
many years were characterized by reduced turbidity and nutrient levels
and contained fewer thermotolerant (faecal) coliforms. They also
supported increased richness and abundance of macroinvertebrates. In
contrast, control (unfenced) dams tended to have high abundance of a few
macroinvertebrate taxa. Notably, differences remained between the
macroinvertebrate assemblages of fenced dams and nearby ‘natural’
waterbodies. Our results show how management interventions can improve
water quality in farm dams and provide a valuable reference and baseline
for longer term studies of farm dam improvement.