Sustainability

 

Natural Resources

 


 

Tree Planting


Tree planting at Rapanui has been a huge success with designed reforestation helping to control erosion, water logging and salinity while improving the quality of water and aesthetics of the landscape.

Tree planting at Rapanui started seriously in 1984. Problems of soil erosion from wind and rain which was disturbing the soil profile lead to the decision to restore some of the land back to forested vegetation. It was also becoming increasingly evident in WA at this time, that the clearing of trees for agriculture was causing a rise in the water table bringing salt minerals to the surface which would accumulate in the lower profile of the landscape. 

In 1995 the farm underwent a very big plant of 25,000 salt-tolerant local Australian plant species. The project was a part of electricity provider Western Powers’ ‘Greening Challenge’. With support from this project, and over a period of 5 years, 100,000 seedlings were planted at Rapanui. This project also included the establishment of a 140ha block of tree alleys using eucalypts. Alleys absorb rising ground water and provide shelter for sheep as well as allow crops to grow in between.

Tree planting has become a continuous annual event since 1995. Government funded catchment projects to plant seedlings and initiatives to help pay a percentage of the fencing were great incentives.  In 2003, another big plant of 50,000 seedlings was completed under the Conservation and Land Mangement (CALM) ‘Search’ Farm Forestry Development Program.

Also around the time of the ‘greening challenge’ were prospects of value adding with the production of Australian mallee trees. There was the potential for these trees to be harvested every 5-10 years for the production of oil for medicine, fuel, and carbon. In 2006, 37,000 mallees were planted in alleys and along valleys, while in the same year 35,000 seedlings of mixed species were planted for conservation and salt control.

The result of the reforested areas is profound. There has been a noticeable slow-down of running surface water and therefore stream-bank erosion has been reduced and productivity has increased. Salt encroachment has also eased with the increased vegetation cover.

Encouraged by these results our enthusiasm for ongoing conservation works has been supported by specialist local consultants, Landcare officers and Envirofund assistance from the Australian Government.


Planting Specifications

 
A variety of plant species are chosen. All of the plants used are native to the region. A mixture of trees, bush and understorey are used to simulate the type of environment which would naturally occur in the area.

The species chosen and the location in which they are planted is dependent on the soil type and water quality they are best suited to. The main varieties of species are listed:

 

Species

Eucalyptus loxophleba ssp. loxophleba

Eucalyptus loxophleba ssp. Lissophloia 

Eucalyptus astringens

Eucalyptus occidentalis

Callistemon phoeniceus

Melaleuca uncinata

Eucalyptus sargentii

Melaleuca cuticularis

Casuarina obesa

Acacia acuminata

Common name

York Gum

Smoothed Bark York Gum

Brown Mallet

Flat Topped Yate

Fiery Bottlebrush

Broom Bush

Salt River Gum

Salt Water Paperbark

Swamp Sheoak

Jam Tree

Water capture & conservation


Rapanui is a Winter rain-fed system with 350-450mm of rain falling mainly between May to September. It is important that crops have the opportunity to maximise water use during the winter months and it is also important to capture this water in order to carry livestock through the drier months of the year. The prevention of soil erosion is also critical and therefore the main aim is to slow the run-off of water over the landscape.

Contour banks or grade-banks have been vital to water management at Rapanui since the land was cleared for Agriculture in the 1930’s. The bank is constructed across the land slope usually in the middle to upper landscape where there are hill slopes between 2-10%.

The purpose of a contour bank is to:

1. control the volume and velocity of run-off on sloping land to prevent soil erosion and allow crops and pasture the opportunity to extract this water    through their root system;
2. decrease flooding , inundation, and water logging, and reduce the potential for the development of salinity in the lower landscape, by diverting run-off to a safe disposal point; and
3. form a part of a water management system that includes waterways and dams which can store water for livestock such as sheep.

Rainwater is also captured in tanks for human consumption. Several buildings on the farm harvest water via rooftop.