Ecosystem response to management of an invasive N2-fixing tree in Hawaiʻi
| Authors: | Flint F. Hughes, Caitlin Morrison, Edward Bufil, James Leary |
| Year: | 2025 |
| Type: | Scientific Journal |
| Station: | Pacific Southwest Research Station |
| DOI: | https://doi.org/10.1016/j.tfp.2025.100932 |
| Source: | Trees, Forests and People |
Abstract
Many non-native tree species are recognized as problematic to ecosystems they have invaded, and subsequent control efforts have met with varying levels of success. Falcataria falcatais a fast-growing, N-fixing tree that has aggressively invaded landscapes across the Hawaiian Archipelago. Due to their ability to alter Hawaiʻi’s native forest ecosystems, large stature at maturity, and potential for catastrophic tree fall, F. falcatastands pose threats to Hawaiʻi’s native forests, residential communities, and agricultural lands. We investigated responses to chemical control of F. falcatastands immediately after control and during ensuing initial stages of succession. Herbicide treatment of F. falcatastands increased litter inputs of N and P that translated to increased soil nutrient availability. Such increases were exploited by extant understory vegetation consisting of non-native grasses and forbs that formed a continuous layer to severely limit the documented maximum potential germination of nearly 8 million F. falcataseedlings per hectare. Although trajectories of post-control vegetation development were dominated by non-native species in this case, control strategies could be employed to incorporate purposeful plantings of native Hawaiian species, non-native but bio-culturally important species, or desired agricultural species. In the absence of such interventions, however, non-native vegetation dominance following F. falcatacontrol presents a daunting barrier to any hope for native species establishment. Overall, findings indicated that F. falcatacontrol is possible and feasible where understory vegetation is allowed to respond to increased light and nutrient resources and limit potential seedbank recruitment that would otherwise lead to F. falcatastand reestablishment.