Summary

The reference area covered by this paper, the South West Slopes of NSW, is defined in terms of physical location, original natural vegetation and landuse.

Scope and methods for tree and shrub retention, regeneration and re-establishment on farms and other rural land is then outlined, taking into account vegetation and land degradation issues.

Finally, short lists of species suitable for use in retention, regeneration, re-establishment and treating saline areas are provided.

Figure 1. Reference area - South West Slopes of NSW

Defining the Reference Area

There is an inherent difficulty when recommending tree and shrub species for farm use. This arises from the range of factors to be considered.

The specific factors need to be addressed in terms of physical location, purpose of retention or establishment and consideration of the original natural vegetation. These specific factors, such as soil type, slope, climate, land and vegetation degradation issues, all have a part to play in the final recommendation.

Comments made in this paper generally refer to that part of the South West Slopes of NSW delineated in Figure 1. This is confined to the area between the mid-reaches of the Lachlan and Murray Rivers.

The area may also be defined in terms of the original major natural vegetation communities. These have recently been described and mapped (AUSLIG 1990).

In summary, these plant communities can be described as eucalyptus dominated woodlands and open forests with a foliage cover between 10 and 70%.

The lower or understorey strata consisted variously of low trees or shrubs and a grassy herbaceous ground cover layer.

This natural vegetation has largely been cleared and replaced with sown pastures and winter crops, leaving only a small percentage of open woodland in the grazing areas in the east (AUSLIG 1990).

Details and comments on trees and shrubs are generally confined to their use in countering vegetation and land degradation, shade and shelter, conservation and wildlife habitat. Tree establishment for direct economic gain (commercial farm woodlots/agroforestry) is not addressed.

How Much Tree/Shrub Cover per Farm?

A minimum of 5 to 10% cover is a good guide for retaining, regenerating and/or re-establishing trees and shrubs on the farm. This does not mean that there is a corresponding loss in agricultural production. This is because the areas so treated are often those of lower productivity (natural bush, rocky recharge areas, eroded gullies). Additionally, multiple environmental and production benefits will accrue within 5 years of establishment at this level of cover.

Increasing Tree/Shrub Cover by Retention, Regeneration and Re-establishment

The three broad methods for increasing tree and shrub cover on farms and public lands are by retention, regeneration and re-establishment.

The aim is to describe these and then to develop a short species list for each of these categories for the South West Slopes.

1. Retention

There is only a small amount of natural (remnant) vegetation remaining in this area. The process of tree decline has resulted in a tree loss variously estimated at between 90 and 100% of the original on a Shire basis (Wells et al., 1984). This extreme tree loss places the region amongst the worst in Australia.

This remnant vegetation continues to be threatened by grazing and agriculture, forestry and a host of construction and development works.

Landholders are therefore advised to start with what remains, if any, and add to it.

Remnant vegetation is at present a largely unrealised asset. Its values are numerous, but generally relate to it having a diverse range of native tree, shrub and ground covers. One aspect is that these plants are adapted to the original environmental conditions and, in turn, the native fauna is adapted to them for habitat and food provision.

Management of Remnant Vegetation

Management of remnant vegetation relates largely to fencing these areas to limit or exclude livestock grazing, trampling of vegetation and soil compaction damage. Timber removal should also be managed and limited.

Any grazing should be restricted to short periods such as off shears in drier times. This use as short term stock protection can be of value and also aids in reducing fuel build up and subsequent fire risk.

Likely sites where remnant vegetation may exist include partially cleared or uncleared hilltops, along creeks and gullies and unused or "green" roads.

One specific dilemma is the question of retaining the individual paddock trees. These are often older and subject to the various causes of dieback (mistletoe, salinity, waterlogging, insect attack, exposed environment, increased soil fertility) and many will die within our current generation. A current loss of 1-2% per year is evident.

To fence out, retain and hope to regenerate trees from a single parent tree can be expensive from the financial, environmental and management point of view. Success will be reduced because of the changed environmental conditions and the limited genetic base of the seed source. These trees are probably best left to fade away gracefully whilst making the best use of them for shade, seed collection and farm timber.

A list of common local trees and shrubs often growing in remnant areas on the South West Slopes and recommended for retention is provided in Table 1(a).

2. Natural Regeneration

Some potential for natural regeneration to occur exists around the margins of remnant vegetation areas. Although limited in potential, natural regeneration is to be encouraged, especially as a method of extending existing vegetation at low cost.

Conditions most conducive to natural regeneration are:

- a shallow, fine surface seed bed so seeds are variably buried ideally to a depth approximately two times their diameter. Such a seed bed can be provided following a drought or a fire;

- rising ground temperature and generally in the order of 20oC to promote optimal seed germination;

- adequate soil moisture for germination and initial seedling establishment;

- a viable seed source either in the ground or from a recent seed fall from parent trees;

- low competition from other plants, especially introduced pastures and weeds;

- native pastures favour regeneration due to lower competition and soil fertility.

Natural regeneration occurring alongside remnant vegetation is generally adapted to the pre-European settlement environmental conditions and will be protected by it to some extent.

However, the many environmental changes now evident may cause natural regeneration to be less successful. These changes relate largely to vegetation and land degradation and include tree decline and loss, salinity, soil acidity, soil structure decline, and soil erosion. Additionally, the higher nutrient status of soils generally from the use of improved pastures, fertilisers and nutrient transfer by stock is making some regeneration and some native tree species more prone to insect attack.

One approach may be to allow natural regeneration of species known to be susceptible to these factors to occur, then let individual trees self-select for survival, as an alternative to planting.

Blakelys red gum (Eucalyptus blakelyi), for instance, is susceptible to insect attack. However, its natural regeneration has been prolific given the right conditions. This young regeneration appears less subject to insect attack with most individuals surviving. However, will it only be a matter of time before insects adapt and severely attack the majority of individual trees with a small number surviving?

Experience with red stringybark (Eucalyptus macrorhyncha) following the 1982/83 drought highlights the value of natural regeneration when the right conditions occur.

Although this species was widely killed, especially on rocky areas during the drought, it has been able to regenerate extremely well especially where livestock have been excluded.

Encouraging Natural Regeneration

When considering an area for natural regeneration, include the area at least two times the height of the parent trees out from these same trees. Seed will be dispersed this distance, but generally will not establish directly under the parent tree.

If natural regeneration is to be encouraged on the farm those natural conditions previously listed need to be simulated.

This can be done by:

- selecting areas of unfertilised native pasture near a remnant vegetation seed source;

- reducing weed competition by selective grazing, cultivation, burning and/or herbicide use;

- cool burning to stimulate the germination of seed, especially wattles (Acacia species) and provide a seed bed (Passalaqua, 1991).

Natural regeneration can be slow and sporadic. The eventually wide range of species may not be evident for several years. However, understorey shrubs and ground plants will gradually emerge either from buried hard seed or by seed transported by birds and other fauna.

One method of assisting natural regeneration may be to plant, at low density, the local tree species. These will act both as nurse plants and as an additional seed source for natural regeneration in 5 to 10 years time.

A short list of trees and shrubs likely to successfully regenerate is provided in Table 1(a).

3. Re-establishment

Given the shortage of remnant vegetation and the limited potential for natural regeneration, farmers will have to establish large areas and numbers of trees and shrubs if they are to achieve the suggested 5-10% cover on farms.

They will need to decide what trees and shrubs to establish, by what methods and for what purposes.

Choices will relate to previous experience, land, vegetation and habitat degradation issues to be addressed, the economic costs and production benefits.

Species Selection

In recommending species to establish, guiding principles and methods of establishment are briefly presented. A short species list, compiled from several sources, is provided in Table 1(b).

Readers are referred to more comprehensive species lists for specific locations and uses, which exist for this and other areas (NSW Forestry Commission, 1981-85; Nicholls, 1986; Oates and Clarke, 1987; Kalma, 1989; Ive, 1990; Cremer, 1990).

Brief mention is made of species for use in and around waterlogged and saline areas with species also listed (Table 2).

Use of Local Species

From the previous comments, it follows that local native tree and shrub species should be chosen for establishment where possible. This gives the potential for improved survival beyond the planted generation by potential natural regeneration.

However, as previously mentioned, there are now situations where the original species will no longer grow well because the site has been so modified.

Additionally, many introduced native and exotic species will do very well and can be used in many situations.

The question is asked as to whether they survive more than the one generation. River She Oak (Casuarina cunninghamiana) is one such local species widely planted and acclaimed. But will it survive away from its natural river bank habitat? Taylor (1991) suggests that, because we don't have the long term experience with this and other species, we just don't know the answer on long term survival.

There is therefore a need to select species suited to a particular site and purpose.

Nevertheless, Greening Australia recommends selecting species where possible in the following order of preference:

1. indigenous (local) species

2. other Australian species

3. exotic (non-Australian) species (Youl, 1991).

The values of local species are outlined by Cremer (1990) and include the following:

- they form an integral part of the natural landscape and are adapted to the original local environment;

- they have the greatest value for native wildlife;

- they maintain local species diversity;

- they often have mechanisms to survive fire and will mostly regenerate naturally given the right conditions.

What to Look for in a Species

Cremer (1990) further lists the points to consider when choosing a species or species mix for a particular purpose and/or site.

These include:

- size and form of species

- value for timber and related products

- possible effects of vegetation and land degradation on the species

- potential for the species becoming a weed

- food value - livestock or human

- opportunity for natural regeneration

- longevity and growth rate

- habitat created for wildlife or vermin

- tolerance to insects and diseases in the area

- cost of establishment and maintenance

- compatibility with existing vegetation

- possible effects of trees on adjacent pastures and crops

Methods of Establishment

Methods of tree and shrub establishment have been widely considered elsewhere (Sharpe and Bellingham, 1989; Campbell et al., 1990; Bell and Nicholls, 1990). They are briefly referred to here with some emphasis on the newer techniques of using open rooted stock and direct seeding.

Natural regeneration - as previously outlined

Tube stock plantings - This is the traditional method of using seedlings 10-40 cm high raised in pots. Establishment costs range from $1.00 to $5.00 per tree depending on site preparation, protection provided and seedling source.

Open rooted stock - This method uses seedlings raised in beds with roots and tops periodically pruned. They are then planted bare rooted. They are being used selectively and are cheaper than tube stock although the species range is limited and they require a more sensitive establishment management. Establishment costs are from 50c to $4.50 per seedling.

Direct seeding - This method uses tree and shrub seed sown directly into the ground by hand or machine. Shortage of local experience in implementing this technique and availability of local species seed in the quantities required to cover broad scale areas are seen as limitations to this method.

These limitations are currently being addressed. Direct seeding machines are now being used and trialled in this area.

Knowledge about seed collection is being enthusiastically spread and received at workshops run by groups including Tree Planters Wagga Wagga, Greening Australia, and Landcare groups.

There still remains an opportunity for professional seed collectors and the establishment of seed orchards to increase seed availability.

Rising Water Tables and Dryland Salinity

The rapidly emerging major issue of rising water tables and associated development of dryland salinity affecting sustainable land use is forcing consideration of ways to address this problem. This includes the role that trees and shrubs will play.

What species and where to establish in relation to recharge and discharge areas within or alongside saline areas, at what densities and the relative merits of deep rooted perennial pasture species are all being given consideration.

The technique of mounding, raising beds on which to plant, to initially keep roots out of saline water, is currently being trialled (Bell, 1991).

Experience in these areas is limited but developing. However, the species listed in Table 2 are salt tolerant for use or trial in saline areas..

End Comment - Farmer Experience

Farmer participants in the cooperative Riverina Trees on Farms program were asked to list their favourite tree species for establishment (Bray et al., 1990).

It is interesting to note that they often selected a local species from their area, another non-local Australian native species and an exotic species in about equal proportions. For the South West Slopes area, yellow box (Eucalyptus melliodora), River She Oak (Casuarina cunninghamiana) and Allepo pine (Pinus halepensis) were the most popular and on about a par.

Acknowledgements

The author wishes to acknowledge the many helpful comments on content and species lists provided by the following people: Charles Bell (Conservation and Land Management, Wagga Wagga), Ted Nicholls (Forestry Commission, Narrandera), N. Marcar (CSIRO), Noel Passalaqua (Jayfields Nursery, Holbrook), and Ian Taylor (Taylor's Nursery, Cookardinia).

References

1. AUSLIG (1990). Atlas of Australian Resources, Vol.6 - Vegetation - Dept. of Administrative Service, Canberra.

2. Bell, C. (1991). Pers. Comm.

3. Bell, C. and Nicholls, E. (1990). Establishing Trees on Farms - A General Planting Guide. Trees on Farms Newsletter, NSW Govt., Wagga Wagga.

4. Bray, S. et al. (1990). Trees on Farm Program - Riverina Region 1985-89 Report. NSW Govt. Wagga Wagga.

5. Campbell, R. et al. (1990). Victoria Felix - Improving Rural Land with Trees. 2nd Ed. Dept. of Conservation and Environment, Melbourne.

6. Costermans, L. (1983). Native Trees and Shrubs of South Eastern Australia. Rigby, Sydney.

7. Cremer, K.W. (1990) (Ed.) Trees for Rural Australia. CSIRO Canberra. Inkata Press.

8. Frankenberg, J. and Rose, S. (1990). Some Native Tree and Shrub Species in the West Hume Landcare Group Area - Howlong.

9. Green, R. Some Native Tree and Shrub Species to Collect in the Wagga Wagga Area. Greening Australia, Wagga Wagga.

10. Hansen, A. and Green, R. Some Native Tree and Shrub Species in the Cootamundra Area. Greening Australia, Wagga Wagga.

11. Ive, J. (1990). Recommended Native Species for Planting in the Yass Valley. Yass River Valley Revegetation Project.

12. Kalma, M. (1989). Planting Trees on the Southern Tablelands. Greening Australia, Canberra.

13. Nicholls, E. (1986). Species Recommendation Lists (various). Forestry Commission of NSW, Narrandera.

14. Nicholls, E. (1991). Pers. Comm.

15. NSW Forestry Commission (1981-85). Species Recommendation Lists (various) - Narrandera.

16. Oates, N. and Clarke, B. (1987). Trees for the Back Paddock. Goddard and Osbson, Melbourne.

17. Passalaqua, N. (1991). Pers. Comm.

18. Sharpe, G. and Bellingham (1989). Trees on Farms - Getting Started. Greening Australia, Sydney.

19. Taylor, I. (1991). Pers. Comm.

20. Wells, K., Wood, N. and Launt, P. (1984). Loss of Forest and Woodlands in Australia. Technical Memorandum 84/4 CSIRO Div. of Water Resources and Land Resources.

21. Youl, R. (1991). "The Right Tree in the Right Place". Greening Australia Newsletter No. 1, July 1991. Canberra.

Table 1(a). Indigenous Tree and Shrub Species for Retention, Regeneration and Re-establishment - South West Slopes of NSW

Larger Trees

Apple box - Eucalyptus bridgesiana
Black Cypress Pine - Callitris endlicheri
Blakelys Red Gum - Eucalyptus blakelyi
Bull Oak - Allocasuarina leuhmannii
Fuzzy Box - Eucalyptus conica
Kurrajong - Brachyton populneus
Grey Box - Eucalyptus microcarpa
Hill Gum - Eucalyptus dwyeri
Long Leaf Box - Eucalyptus goniocalyx
Mugga Ironbark - Eucalyptus sideroxylon
Red Box - Eucalyptus polyanthemos
Red Stringybark - Eucalyptus macrorhyncha
River Red Gum - Eucalyptus camaldulensis
River She Oak - Casuarina cunninghamiana
Tumbledown Gum - Eucalyptus dealbata
White Box - Eucalyptus albens
White Cypress Pine - Callitris glaucophylla
White/scribbly Gum - Eucalyptus rossii
Yellow Box - Eucalyptus melliodora

Smaller Trees

Cootamundra Wattle - Acacia baileyana
Currawong - Acacia doratoxylon
Drooping She Oak - Allocasuarina verticillata
Golden Wattle - Acacia pycnantha
Hakea Wattle - Acacia hakeoides
Hickory/Lightwood - Acacia implexa
River Bottlebrush - Callistemon sieberi
Silver Wattle - Acacia dealbata
Yarran - Acacia omalophylla

Shrubs

Australian Indigo - Indigofera australis
Bent-Leaf Wattle - Acacia flexifolia
Box Leaf Wattle - Acacia buxifolia
Bursaria - Bursaria spinosa
Bush Peas - Pultenaea species
Coil Pod Wattle - Acacia pravifolia
Common Fringe Myrtle - Calytrix tetragona
Daphne Heath - Brachyloma daphnoides
Dean's Wattle - Acacia deanei
Drooping Wattle - Acacia difformis
Gold Dust Wattle - Acacia acinacea
Spider Flowers - Grevillea species
Guinea Flowers - Hibbertia species
Kangaroo Thorn - Acacia paradoxa
Mallee Wattle - Acacia montana
Parrot Peas - Dillwynia species
Peach Heath - Lissanthe strigosa
Prickly Moses - Acacia unicata
Prickly Tea Tree - Leptospermum juniperinum
Red Stem Wattle - Acacia rubida
Rough Wattle - Acacia aspera
Round-Leaf Wattle - Acacia rotundifolia
Silver Banksia - Banksia marginata
Spreading Wattle - Acacia genistifolia
Streaked Wattle - Acacia lineata
Wedge Leaf Hopbush - Dodonea viscosa spp. cuneata
Western Silver Wattle - Acacia decora
Woolly Wattle - Acacia lanigera

Note: Seedlings or seed supplies of some of the above species, especially shrubs, are unavailable commercially at present. This may necessitate seed collection, direct sowing and/or propagation of tube stock.

Some of the shrubs listed are prickly and unpalatable to livestock and may be considered as rabbit harbour. However, they have potential as wildlife habitat species including in unfenced areas where stock and predators are kept at bay.

Compiled by R. Green with the assistance of J. Frankenberg, A. Hansen, S. Rose and J. Webb.

Table 1(b). Non-Indigenous Tree and Shrub Species for Establishment - South West Slopes of NSW

Allepo Pine - Pinus halepensis
Black Sally - Eucalyptus stellulata
Blackwood - Acacia melanoxylon
Blue Mallet - Eucalyptus gardeneri
Boree/Myall - Acacia pendula
Canary Island Pine - Pinus canariensis
Flinders Range Wattle - Acacia iteaphylla
Giant Honey Myrtle - Melaleuca armillaris
Green Mallee - Eucalyptus viridis
Green Wattle - Acacia decurrens
Gungunnu - Eucalyptus caesia 'Silver Princess'
Heath Banksia - Banksia ericifolia
Hybrid Belah - Casuarina cristata x cunninghamiana
Manna Gum - Eucalyptus viminalis
Moonah - Melaleuca lanceolata
Narrow Leaved Peppermint - Eucalyptus nichollii
Native Willow - Acacia salicina
Orange Wattle - Acacia saligna
Paddy's River Box - Eucalyptus macarthurii
Pepper Tree - Schinus areira
Red Flowering Yellow Gum- Eucalyptus leucoxylon rosea
Rosemary Grevillea - Grevillea rosmarinifolia
Round Leaved Moort - Eucalyptus platypus
Silky Oak - Grevillea robusta
Steedman's Gum - Eucalyptus steedmanii
Swamp Gum - Eucalyptus ovata
Swamp Mallet - Eucalyptus spathulata
Swamp Yate - Eucalyptus occidentalis
Tagasaste - Chamaecytisis proliferus
Tall Sand Mallee - Eucalyptus eremophila

Note: The purpose(s) and site location for which trees and shrubs are required need to be assessed before species selection is made.

Table 2. Salt Tolerant Trees and Shrubs for use on the South West Slopes of NSW

Athel Tree - Tamarix aphylla
Bluebushes - Maireana species
Blakelys Red Gum - Eucalyptus blakelyi
Gippsland Mallee - Eucalyptus kitsoniana
Grey Bulloke - Casuarina obesa
Native Willow - Acacia salicina
Old Man Saltbush - Atriplex nummularia
Orange Wattle - Acacia saligna
Paddy's River Box - Eucalyptus macarthurii
Prickly Paper Bark - Melaleuca stypheloides
Prickly Tea Tree - Leptospermum juniperinum
River Red Gum - Eucalyptus camaldulensis
River Red Gum - Eucalyptus camaldulensis spp.
Lake Albacutya
River Red Gum - Eucalyptus camaldulensis
(Silverton Gum) - subcinerea
River Red Gum - Eucalyptus camaldulensis spp.
(Blunt Budded) obtusa
River Saltbush - Atriplex amnicola
River Cooba - Acacia stenophylla
Salt Paperbark - Melaleuca halmaturorum
Sargents Mallet - Eucalyptus sargentii
Stocking Gum - Eucalyptus kondininensis
Swamp Gum - Eucalyptus ovata
Swamp Oak - Casuarina glauca
Swamp Paperbark - Melaleuca ericifolia
Swamp Yate - Eucalyptus occidentalis

Compiled by R. Green with the assistance of C. Bell, N. Marcar and N. Passalaqua.

Note: The above is a current suggested list of species for use in and around dryland salinity sites. Each species' response can be a complex interaction of salt tolerance and tolerance to waterlogging. Each species will thus exhibit a low, moderate or high tolerance, dependent on site location, the species and its trueness to type. Some species listed may be unsuitable in specific locations due to other factors including frost, drought and insect susceptibility.