Linking Restoration and Ecological Succession (Springer ... - Inecol

78 Joe Walker and Paul Reddell
discounted simply by their failure to reduce all leakage to the groundwater.
Other benefits accrue because in Australia many perennial pastures contain a
legume, such as lucerne that adds nitrogen to the system; rotations of crops
and pastures are generally employed for weed control and to reduce the use of
pesticides; and critically, well-managed crop-pasture rotations can build up soil
organic matter.
4.4.4 Engineering Solutions
The perceived limitations of revegetation solutions using trees alone have led
to more effort being put into engineering solutions. These focus on reshaping
landforms, surface water removal, salty water removal, and enhanced discharge
from the ground water system (McFarlane and Cox 1990, Cox and McFarlane
1995). Drainage options at local scales usually take the form of shallow drains
to intercept overland flow (interceptor drains) and soil interflow, moving the
water quickly off-site (Hatton 2002). The main issues with moving salty water
off-site are that first, salt loads are exported further down the catchment, and
second, if the water is of good quality (e.g., storm water), then it is lost from
the farm. Interceptor drains have little impact on deeper ground waters moving
through the landscape and can be combined with tree planting immediately
down slope to try and use up this water. The impact of tree belts combined with
drains can provide a localized impact on the shallow ground waters (Hatton
2002). An alternative to shallow interceptor drains is groundwater pumping
combined with deep, open drains. This method is widely used at local and
regional scales to remove saline waters and dispose of them into the stream
networks of the region (Otto and Salama 1994). Draining and pumping can be
effective in reducing the impacts of land-based salinization on urban and rural
infrastructure and in maintaining an area under crops and pastures. However,
moving large volumes of salty water off farm has impacts on stream biota and
industries that depend on good quality water.
Natural sequence farming (NSF) is an engineering approach to manipulate the
local hydrologic regime to reuse and store water within the floodplain elements
of a landscape (Newell and Reynolds 2005). Small structures are used to spread
stream flows out across the floodplain and to dam incised stream channels at
a number of points. Small banks are also constructed at the break of slope
where the surrounding hills meet the floodplain. This break reduces the velocity
of water moving through the floodplain and increases aquifer water storage.
Sedimentation gradually refills the incised channels and is also deposited on the
floodplain, adding nutrients to the system from areas upstream. In effect, NSF is
an approach to moisten the surface soils and return the floodplain to the original
“chain of ponds” drainage system. The ponds are colonized by dense stands of
reeds that retain nutrients and help regulate water movement off the property.
To date, the NSF method has been applied extensively to a single property and
there is insufficient data to quantify the impacts. However, the method does
appear to improve soil organic matter, slow down deep drainage, and reduce
export of salt from the property. NSF appears to include many hydrogeological
and ecological principles and there is visual evidence of improved productivity,
especially during drought periods. But potential applications elsewhere have
several restrictions: NSF will be limited to local groundwater systems with low
salt content and to landscapes that have surrounding hills to supply fresh water