Invasive plants are changing ecosystems in the tropics more quickly than they can be studied or documented, with powerful effects across three continents. Research led by Avinash Mungi and Jens-Christian Svenning highlights the pervasive spread of species such as Lantana and Prosopis juliflora, which are transforming landscapes in countries like India, Australia, and the United States. Scientists from Brazil, Ethiopia, India, and the US worked together on this study. More importantly, it demonstrates the competitive interactions between invasive species and native ecosystems.
Once native to the tropical Americas, Lantana has now invaded over 30 million hectares in India alone. This invasive plant species suffocates native nutritious food plants in forest and savanna ecosystems. It doesn’t take long for the herbivore populations to crash, creating even more obstacles for carnivores. The repercussions sweep through landscapes and seascapes, affecting biodiversity and disrupting species interactions.
In Australia, lantana is declared a noxious weed on over 4 million hectares of land. Invasive water hyacinth has invaded a village-owned pond in a remote village of northern India. Water crisis — This disruption is severely impacting the local water systems. At the same time, Prosopis juliflora has spread over great swathes of dry grasslands, where it is used as an alternative feedstock for biochar.
Invasive species are not the exception, rather the rule. Indeed, about 10,000 non-native plants flourish across the expanded tropics. Indeed, most of the species we focus on today have been introduced due to their practical benefits. As Mungi points out, “Many alien species are imported for their usefulness and value, but few escape and become invasive with undesirable impacts.”
The local communities have written plays, songs and cookbooks to address the challenges posed by these invasive species. They manufacture value added furniture from Lantana and utilize water hyacinth to produce commercial products. Mungi emphasizes this adaptation: “In many places across the greater tropics, the locals have started using invasive plants… They have, in other words, adapted to a new reality.”
Yet for all their usefulness, there are substantial hurdles to controlling invasive plants. As Mungi explains, “The problem with managing widespread invasive plants is that it’s very costly to completely eradicate them.” Variable eradication success makes eradication more complicated for these species, as reinvasion often occurs.
As Svenning notes, alien plants can be either beneficial or detrimental, and often both at the same time. He states, “While invasive species need focused management, other more neutral alien species can sometimes offer a positive ecological role.” Such complexity requires an intentionally nuanced strategy to ecosystem management, especially as climate change makes ongoing impacts to native biodiversity increasingly inevitable.
“Since invasive plants have spread across the natural areas, they simply can’t just be bulldozed, as that can have several undesirable impacts on the ecosystems. A sustainable alternative is urgently needed.” – No specific author mentioned
Both researchers emphasize the need to work with local communities to determine the best management strategies. “Local communities are often more aware about the local ecosystem and about creative ways of management,” notes one of the researchers.