2026/07/30 by Rebecca J. Cole, Christine J. Pardo Dewald, Francis H. Joyce +3
paper · doi:10.15517/7jtv6t72
Introduction: Zingiber spectabile, a shade-tolerant ornamental ginger native to Southeast Asia, is invading tropical wet forest understories in Central America. This shade-tolerant species is of concern, yet no ecological impact or management assessment exists. Objective: To examine the invasion patterns of Z. spectabile in primary and secondary forests, reproductive capacity, effects on understory vegetation, and the effectiveness of control efforts. Methods: Field trials were conducted in 30-year-old secondary forest and in primary forest remnants in southern Costa Rica that were invaded by Z. spectabile, which was introduced to the region in the early 1990s. Control efforts consisted of aboveground biomass removal and herbicide application to rhizomes. Results: Both primary and secondary forests showed substantial invasion, but stem and inflorescence densities and aboveground biomass were three-fold higher in secondary forests, suggesting that secondary forests are more susceptible to invasion. Z. spectabile exhibited high reproductive capacity via prolific nodal sprouting (all cut stems producing 5.8 ± 0.3 rooted sprouts); inflorescences produced 64.3 ± 7.9 seeds each, yielding approximately 104 717 to 312 314 seeds/ha across invaded sites. Seed germination rates were similarly high in primary (58 %) and secondary (47 %) forests but lower in pasture (3 %). With one year of control efforts, Z. spectabile reinvaded, regaining over 35 % of aboveground biomass. During the first year following control, native herbaceous plant density increased by 61.5 % in secondary forest; there were no significant responses of woody seedlings or saplings in either forest type. Conclusions: These findings suggest that Z. spectabile invasion affects some components of understory plant communities, especially in secondary forests, and underscores the need for longer-term studies of invasion impacts and understory responses to control. Given the labor-intensive nature of biomass removal and the limited effectiveness of herbicides, improved and scalable management strategies are urgently needed.