Native forest degradation and exotic species alter the ecological interaction between two species in Chile
A research team, with the participation of the Doñana Biological Station – CSIC, has studied how human impact through the introduction of exotic species and habitat transformation, can severely alter ecological interactions between a threatened endemic plant and one of its most important mutualist animals, which has important consequences for the conservation of both species.
The Andean Araucaria, a threatened species, has a particular seed production strategy. During the masting years, it produces high quantities of seeds while in non-masting years, this production is much lower. This strategy allows the plant to feed seed predators, such as the Austral parakeet (Enicognathus ferrugineus), that may also act as dispersers and they can, therefore, ensure that some seeds will prevail. However, in fragile ecosystems, the introduction of exotic species can alter these ecological processes.
In this new work, the researchers have observed that in masting years, the large seed crop allows massive use of these resources by the Austral parakeet. However, in non-masting years, this species especially feeds on exotic plants. "This is because, in non-masting years, this resource is entirely consumed by livestock and other mammals introduced by humans, forcing Austral parakeets to use other resources", explains Pedro Romero Vidal, a researcher at the Doñana Biological Station. "The disappearance of the native forest forces Austral parakeets to move to anthropogenic habitats and exploit field crops". The mutualistic interactions between the two species are so fragile that any alteration can have negative consequences for both species and also for the ecosystem functioning.
This change in diet, from consuming native species to exotic species, especially those cultivated by humans, may even lead to a change in people's perception of this parakeet species. Farmers may consider it a harmful species that cause economic losses, as it occurs with other parrot species in other Neotropical areas due to the damage they cause to crops. "This perception, sometimes based on minimal impacts, can lead to direct persecution or an increase in illegal hunting, conservation problems that would add to those already experienced by this species due to habitat loss and changes in land use", says Romero Vidal.
This study was carried out in the northern Patagonian Andes over four years. To reach these results, the team conducted surveys to estimate the abundance of parakeets and recorded the food plants consumed by them. This work highlights the importance of mutualistic interactions between plants and animals and how they can be altered by anthropogenic activities. However, it is important to continue investigating the implications of the losses of these interactions on species, especially considering the threats that suffer such specific ecosystems, such as Araucaria forests.
These studies are essential to promote appropriate conservation strategies. The huge changes due to human action in ecosystems make it all the more important to understand the new ecological interactions, how they can affect native species and how human impact on threatened species can be minimized. Moreover, it will allow reducing the impact that these changes in the behavior of some species can have on humans and social perception they have of them.
Guillermo Blanco, Pedro Romero Vidal, José L. Tella, Fernando Hiraldo. Novel food resources and conservation of ecological interactions between the Andeand Araucaria and the Austral parakeet. Ecology and Evolution. https://doi.org/10.1002/ece3.9455https://doi.org/10.1002/ece3.9455
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