Technical and financial evaluation of enrichment planting in logging gaps with the high-value species Swietenia macrophylla and Handroanthus serratifolius in the Eastern Amazon

Enrichment planting in logging gaps is an important silvicultural treatment to ensure long-term wood production in tropical forests. Knowledge on environmental and economic aspects of enrichment planting with high commercial value timber species in logging gaps is scarce, which creates uncertainty for decision makers about the method effectiveness. To contribute to the debate, this work aimed to evaluate technically and financially enrichment planting of Swietenia macrophylla and Handroanthus serratifolius in logging gaps to serve as a model in the recovery and production increase of these species in future cutting cycles. An experiment on enrichment planting was established in 46 logging gaps in 2009 and measurements of planted individuals were done in 2011, 2014, and 2017. A cost-benefit analysis using net present value (NPV) and a sensitivity analysis were carried out on different interest rates for the production of roundwood and sawnwood. Eight years after planting, individuals of Swietenia and Handroanthus presented a diameter at breast height of 7.88 +/- 1.41 cm and 5.20 +/- 1.00 cm, and a Periodic Annual Increment (PAI) of 0.98 +/- 0.38 cm year- 1 and 0.65 +/- 0.22 cm year- 1, respectively. At the last measurement, Swietenia and Handroanthus individuals had a survival percentage of 51% and 24% and a mortality rate of 8% and 16% year- 1, respectively. NPV was positive for Swietenia in roundwood and sawnwood harvested at 60 and 90 years after planting (2nd and 3rd cutting cycles) and for Handroanthus in sawnwood harvested 90 years after planting. Once increasing PAI in 10% and 20%, Swietenia presented the highest NPVs and Handroanthus was profitable with harvest in 60 years and PAI increasing 20%. Based on these results, a model of Swietenia and Handroanthus production and conservation through enrichment planting in logging gaps was built.

Automated summary

Enrichment planting in logging gaps is essential for long-term wood production in tropical forests. This study evaluated the technical and financial aspects of planting Swietenia macrophylla and Handroanthus serratifolius in logging gaps, showing positive growth and economic benefits over time. Based on the results, a model for production and conservation of these species through enrichment planting was established.