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

Chapter 4 Retrogressive Succession and Restoration on Old Landscapes 79
and sediment to the floodplain. In addition, NSF as currently implemented is in
areas that previously had chains of ponds. Nevertheless, the broad principles in
NSF that focus on improving soil organic matter and moistening surface soils
rather than drying them out, follow the proposed end-points of restoration in
the salinized landscapes outlined in 4.3.
4.4.5 Boosting Soil Organic Matter
The importance of organic matter and diverse soil biota in the restoration of
salinized areas is poorly represented in the literature. Yet organic matter can become
a major regulator of water movement into the subsoil. Higher surface-soil
moisture levels will also improve the function of soil biota in regulating hydraulic
properties and in biochemical cycling. The importance of soil microbes
and fauna in regulating many ecosystem functions is well articulated by Neher
(1999), Lavelle (1997), and Lavelle and Spain (2001; also see Chapter 3). Developing
the means to adjust soil microbe populations to help restore hydraulic
functions in old landscapes is a key research need. In production farming systems
the use of mechanical methods to sow crops into stubble and reuse the
stubble as mulch, have been developed over many years.
Our conclusion is that no single approach is likely to improve landscape
health in all situations and in most cases a combination of approaches aimed
at the belowground systems (abiotic restoration) is the most likely approach to
succeed. In particular, building up the water retention capacity of the surface
50 cm of soil is essential.
4.5 A Possible Restoration Scenario
The broad objectives outlined earlier to reduce the impact or spread of salinity
in southern Australia involve the initial use of broad-acre herbaceous species
as rotations of crops and pastures or salt-tolerant shrubs in discharge areas
to stabilize the initially degraded system. Current activities need to be coupled
with soil organic matter conservation strategies (e.g., managing grazing
pressures, stock exclusion, stubble retention, and composting) to improve soil
moisture retention. Where terrain allows, shallow drains can harvest surface
water, especially after storms. This water should have a low salt content and
can be stored for reuse or to supplement environmental flows down-stream.
Belts of deep-rooted perennial shrubs or legumes around the shallow drains
can increase soil nitrogen, increase soil organic matter, and reduce soil movement.
Planting belts of trees of varying areal extent and species composition
can achieve a range of objectives including reduced run-off and sediment movement,
improved surface soil properties, specialized timber production, honey
production, establishing specific habitats, and wildlife corridors. On crests and
upper slopes pasture species used initially to stabilize the system can be replaced
with deep-rooted shrubs and trees. Species selection should take into
account habitat requirements of local fauna and wildlife corridor needs. Halophytes
can be established in discharge areas and will persist if salt inputs from
the surrounding landscape are reduced.
The conceptual temporal (successional) stages that fulfill the above restoration
scenario for a production landscape are shown in Fig. 4.5. The design is an
elaboration of the “use water where it falls” concept described by McDonagh