Designing a Farm Forest / Design - Balancing multiple goals /
Timber plantations for salinity control
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Designing a Farm Forest

Timber plantations for salinity control

Revegetation of recharge areas is widely acknowledged as being a possible means of controlling the rising watertables that contribute to dryland salinity. Hydrological surveys often identify the principal recharge areas as the cleared well-drained hillslopes where water easily penetrates. To control the recharge farmers are often advised to establish a canopy of evergreen perennial vegetation that can dry the soils to a suitable depth or intercept subsoil drainage. The trees or shrubs do not necessarily need to be indigenous, or even native, but they must be able to grow well on the site and survive droughts and/or other threats. The costs associated with revegetation and the subsequent loss of agricultural production from the planted area represent a real and substantial investment, whereas the environmental return is often uncertain, not immediate and difficult to describe in dollar terms.

Depending on a farmer's other interests, he/she might consider establishing a commercial plantation on the recharge site. If an industrial forestry company is offering a commercial joint venture or lease, they may be able to negotiate for a plantation to be established on the site. To be effective in controlling salinity, the plantation must be located correctly, remain productive and be harvested in a way that doesn't allow recharge to return to the pre-planting levels. This may mean that conventional plantation species or management methods are inappropriate. For instance, Blue Gum (E. globulus) is susceptible to drought deaths on dry, well-drained sites so alternative, although less vigorous, species such as Sugar Gum (E. cladocalyx) may be more suitable. If such areas are also difficult to access and expensive to harvest, growing low value products like pulpwood would be unviable, whereas sawlogs may be viable to harvest due to higher log values.

Although the site may not be ideal for high value timber production, a farmer may be willing to accept a lower return, in order to achieve salinity control. This may mean lower lease payments or lower prospects of deriving a profit from the timber. Where the costs of establishing a non-commercial forest are prohibitive, the multipurpose option reduces a farmer's exposure to risk while meeting their most critical environmental concerns. The fact that the plantation is not viable to establish on the basis of timber production alone is not critical. What is important for timber production is that the trees are viable to harvest at some time in the future.

Waterlogging and salinity
Planting trees to reduce waterlogging and salinity



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