Planting methods matter for cost-effective rainforest restoration

Forest restoration efforts in Australia's Wet Tropics establish <100 ha/year, compared with 20-year average clearing rates of 1661 ha/year. Establishment costs are serious impediments to restoration efforts. Costs range from $25,000 to $67,000/ha, compared with less than $5,000/ha in other areas using other methods. Some of this difference stems from methods used to plant trees. Augered holes are used commonly in environmental plantings, whereas planting spades are used mostly in forestry plantings. To determine the most cost-effective planting method between auger and spade planting methods, we compared the planting costs and the survival and growth of seedlings of local rainforest species, The speed of planting with a spade is on average four times quicker than with an auger, whereas the survival (range = 89–94%, spade vs auger respectively), and growth (slightly greater height growth for auger planted individuals) rates were only marginally different. Given these results, using planting spades is a cost-effective alternative to augering holes.