Key words: restoration, planting, riparian, revegetation
Development of the long-stem planting method in Australia has seen an increase in the survival rates of seedlings of a range of species planted in many different environments. While research to test the value of the method for a broader number of species is currently ongoing (see Trials and Results below) the technique has now been successfully used on subsets of species in riparian, rainforest, coastal and saline environments. The advantages of this method are no post-plant watering, increased growth and increased survival rates.
The approach. The long-stem planting method is a way of planting that can result in enhanced survival with minimal post planting care. Seedlings are grown in pots for 10-18 months so that they develop long woody stems. These seedlings are then planted with about three quarters of their long woody stem below ground. Once planted the buried stem develops roots and leaf nodes resulting in the development of a robust root network which gives the seedling a greater chance of survival. This method challenges two long held horticultural practices: (i) that large plants should not be grown in small containers as they will become root bound and will hinder full growth of the plant; and (ii)stems of seedling should not be planted below the surface of the soil as it subjects them to fungal attack and disease.
Trials and results to date: The method was originally pioneered by Bill Hicks in the Hunter Valley to reduce the use of willows in the riparian environment and has now expanded and proved successful in a range of environments and with a variety of plant species. Experimental field trials on the application of the method on particular species have been carried out by researchers at the School of Environmental and Life Sciences, University of Newcastle, and Gosford City Council since 2005 Knowledge of the species that suit this technique is building as more bushcare groups and individuals across Australia continue to trial the technique.
The Environmental Trust funded Gosford City Council and the Australian Plants Society to pull together the current anecdotal and researched information on the use of this technique into a Guide for use by practitioners. (See full Guide at: www.environment.nsw.gov.au/grants/dissemination.htm#longstem). This project found that the main benefit within the riparian environment is that the roots of the seedlings are planted deeply in to the river bank making it harder for them to be washed away. Eucalyptus camaldulensis is one of many species that has show enhanced performance in this environment. In rainforest environments, the long-stem seedlings will often not grow to the suggested one meter prior to planting, but a range of plants such as Glochidion ferdinandi show increased growth once planted.
In the coastal environment this method has shown promise, possibly due to the potential for the deep rooting to reduce root competition, provide additional anchoring (therefore reducing the impacts of sand movement), greater access to soil moisture and reduced impact from heat. Acacia longifolia is one example of a species that has been successfully used in coastal environments. With regards to the saline environments, again the deep rooting is a major advantage as the plants roots are below the salt encrusted upper soil layer. A large range of species have been found to successfully grow using the long-stem technique in this environment such as: Eucalyptus botryoides, Eucalyptus tereticornis, Eucalyptus robusta, Melaleuca styphelioides, Melaleuca linarifolia, Melaleuca quinquenervia, Acacia binervia, Acacia saligna, Casuarina glauca and Casuarina cunninghamiana.
Lessons learned and future directions: Plants need to be grown in pots placed in potting racks so that the roots are air pruned if they protrude from the pot. This will allow the roots to spread out in to the surrounding soil when planted. Soaking the seedlings the night before you intend to plant out the long-stemmed plants assists with their survival. Whilst the long-stem planting technique has been shown to be successful particularly in environments where the surface soil conditions are not favorable for planting, the costs of this technique do need to be considered. Long-stem plants are kept in the nursery for longer than traditional tubestock or direct seeding so there is some increased cost per plant. However, if balanced against the other advantages in environments where establishing vegetation is more challenging, the additional costs can be minor when offset against increased survival.
Stakeholders and Funding bodies: NSW Government’s Environmental Trust, Australian Plants Society – Central Coast Group, Gosford City Council
Contact: Leah Andrews, Senior Project Officer, Environmental Trust 02 8837 6081