Long-term growth-mortality trade-offs of post-harvest silvicultural tending in Amazonian logging gaps

Sustainable timber production under reduced-impact logging (RIL) remains a major challenge in tropical forests because commercial timber stocks often fail to recover within conventional cutting cycles. We evaluated the long-term effects of post-harvest silvicultural tending in logging gaps on three commercial pioneer species ( Goupia glabra , Jacaranda copaia subsp. spectabilis , and Laetia procera ) using a 17-year gap-based experiment in eastern Amazonia. We quantified periodic annual increments in diameter and stem volume, assessed mortality rates and diameter-class structures, and projected the time required to reach a target diameter of 50 cm DBH under tending and control scenarios. Tending significantly increased diameter growth (+0.28 cm yr⁻¹ in G. glabra and +0.24 cm yr⁻¹ in L. procera ) and stem volume accumulation while reducing mortality rates (-3.11% yr⁻¹ in G. glabra and −0.97% yr⁻¹ in L. procera ). However, diameter structures remained strongly dominated by juvenile individuals, and projected recovery times to commercial size exceeded the conventional 25–35-year cutting cycles (97–400 years) even under tending. These results demonstrate that tending improves individual performance and partially shifts the growth-mortality balance for some species. However, it does not overcome the fundamental demographic constraints of low population density and episodic recruitment that characterize pioneer species. Active species-specific silviculture is therefore essential to enhance the long-term sustainability of polycyclic forest management in Amazonian production forests, potentially combined with complementary silvicultural strategies such as enrichment planting to increase stem density and overcome demographic constraints.