Ecological restoration on a tropical island: Removing invasive plants boosts seed-predator insect biodiversity
- A recent study led by researchers from the Institut Mediterrani d'Estudis Avançats (IMEDEA, CSIC-UIB) conducted on the island of Mahé, Seychelles, has revealed that the removal of non-native plants not only enhances biodiversity, but also generates important changes in the interactions between plants and insect seed predators. The research, conducted in a large-scale experiment, showed that ecological restoration drove a sharp increase in the abundance and diversity of these seed predators, which is key to healthy ecosystem functioning.
As humans alter ecosystems, either accidentally or through interventions such as ecological restoration, biotic interactions respond rapidly to these changes. This study specifically evaluated how insect seed predator communities respond when invasive plants are removed. Results show an 81% increase in abundance and 50% increase in species richness of predator species at restored sites, confirming the positive impact of these interventions on biodiversity.
Imagen: Chrysobalanus icaco, one of the invasor species part of the study. Author Malcon Manners
Importance of diversity and frequency of interactions
Although restoration resulted in more diverse seed predator communities, the study reveals that the removal of non-native plants was not sufficient to eradicate non-native seed predators, suggesting the need for additional control measures. In addition, a low predation rate was detected compared to studies on the mainland and nearby islands, suggesting a less important role of insect seed predators in native plant regeneration. However, the impact of predation on the plant community can be positive, neutral or negative, depending on other ecological factors controlling seedling survival and growth.
A model for island restoration
The study underscores the importance of considering not only mutualistic interactions, such as pollination, but also antagonistic ones, such as seed predation, in ecological restoration efforts. In addition, the results confirm that restored communities experience increased specialization in predator-plant interactions, which could be due to the removal of invasive species that supported generalist predators.
Restoration not only improves diversity, but also increases species turnover and interactions within communities, generating greater heterogeneity in restored landscapes. This finding suggests that ecological restoration is key to maintaining seed predator insect diversity, which in turn helps to preserve native plant communities.
Implications for Conservation
From a conservation perspective, the researchers recommend continuing invasive plant control efforts and conducting periodic monitoring to prevent reinvasions. This approach will allow the preservation of ecological interactions critical to the maintenance of biodiversity. However, it is also necessary to implement specific measures to control non-native predators that could continue to threaten the stability of local ecosystems.
This study highlights the importance of carefully managing biotic interactions in the restoration of island ecosystems and offers valuable insights for biodiversity conservation on islands threatened by biological invasions.
Access the full publication here:
https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2664.14781