Non-native and invasive woody trees are increasingly recognized as a major threat to biodiversity, especially after major land-use disturbances. A new multinational analysis examines how these species behave as tropical secondary forests regrow on abandoned agricultural land—an ecological recovery pathway that can either suppress or enable biological invasions depending on conditions on the ground.
Using an unusually broad dataset, researchers assembled 1,561 forest plots and 58 chronosequences across ten Neotropical countries. In total, 3,735 woody species were classified by both origin and invasiveness, allowing the team to focus specifically on non-native species (while assessing native potentially invasive groups separately).
The study reveals that non-native woody species are widespread during succession. They appeared in 81% of chronosequences and formed a substantial fraction of forest composition, representing 18% of woody plots in dry forests and 41% of plots in moist forests.
Timing matters. During early succession—the first 10–20 years—non-native species achieved their highest relative density and richness. In moist forests they accounted for 28% of stems and 22% of species, while in dry forests the contributions were smaller but still notable (9% of stems and species).
Crucially, both metrics declined sharply during the same early-to-mid timeframe, yet non-native species did not disappear. They remained detectable into late succession, indicating that forest maturation reduces but does not fully eliminate invasion pressure.
The decline parallels the trajectory of native pioneer species, suggesting shared ecological constraints. As canopies close and shading intensifies, light-dependent colonizers—whether native or non-native—are increasingly outcompeted.
The analysis also disentangles spatial drivers. Non-native richness rose with the Human Development Index, consistent with higher propagule pressure near more human-influenced regions. In contrast, density and richness were negatively linked to surrounding forest cover, agricultural proximity, and precipitation gradients.
At the soil level, soil organic carbon showed a generally positive association with non-native retention. This points to biogeochemical conditions that may stabilize or favor non-native establishment even as competition intensifies overhead.
Overall, the findings suggest that nature-based solutions are feasible: allowing forests to regrow and maintaining relatively intact surrounding landscapes can curb non-native spread, protecting native biodiversity, ecosystem integrity, and local livelihoods.
Subject of Research: Tropical secondary forest succession; non-native and invasive woody species; ecological drivers of invasions
Article Title: Non-native and invasive tree species are abundant in neotropical secondary forest but decline over time
Article References: Resende, A.F., Poorter, L., Matos, F.A.R. et al. Non-native and invasive tree species are abundant in neotropical secondary forest but decline over time. Nat. Plants (2026). https://doi.org/10.1038/s41477-026-02327-3
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41477-026-02327-3
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