QEII National Trust Southland representative Jesse Bythell, of Wairio, in Western Southland, said the planting was at Kowhai Reach, a rare ecosystem protected for more than 40 years by local farmers.
Supplementary planting would give the forest a boost to ensure it had a long and healthy future, Ms Bythell said.
Planting was planned between 10am and 1pm on Friday, October 27.
Access to the planting area was at the milking shed, 1km north of Chris and Charleen Withy's farm at 134 Benmore-Kauana Rd.
"We will park near the shed and then car-pool to reduce the number of vehicles crossing the farm. Please bring a four-wheel-drive if you can, as the paddock could still be a bit sticky this time of the year."
She hoped the event would be well attended.
"Tell all your friends, the more the merrier."
Volunteers should bring their own spade, work gloves and lunch.
"Please do not bring dogs and if bringing any children they need to supervised at all times, as we will be on a working farm with the usual hazards and are planting along a steep-sided stream bank."
- The event is open to anyone who is interested. Anyone who intends to attend is advised to contact their catchment group co-ordinator or Jesse Bythell on 0204003-2109 or email jbythell@qeii.org.nz.
