Invasive plants are radically transforming ecosystems across the greater tropics, bringing profound ecological shifts and reshaping human interactions with nature. A comprehensive study led by Danish ecologists Ninad Avinash Mungi and Jens Christian Svenning from Aarhus University reveals how alien plant species have spread extensively, often outcompeting native flora and triggering cascading effects throughout tropical and subtropical landscapes. This systematic review synthesizes scientific evidence from multiple continents, illustrating not only the scale of biological invasions but also offering nuanced insights into their ecological consequences and management challenges.
The greater tropics, encompassing the planet’s tropical and subtropical zones, harbor roughly ten thousand foreign plant species, a staggering figure that highlights the magnitude of human influence on global biodiversity. Islands within this vast area have emerged as particularly vulnerable hotspots, sometimes supporting more alien plants than native species. The effects transcend botanical displacement; these invasive plants alter critical ecosystem functions, threatening the delicate balance upon which indigenous wildlife and human populations depend. Despite the alarm these numbers might cause, it is crucial to recognize that the majority of alien species do not exert harmful impacts, reflecting a complex interplay of ecological variables.
One emblematic invasive species detailed by the researchers is Lantana camara, a plant native to tropical Americas that has proliferated throughout much of the world’s tropical regions. Introduced initially as an ornamental during the colonial era, Lantana now dominates millions of hectares of land, notably in India’s Western Ghats. Its unchecked spread has triggered substantial social and ecological disturbances, including the displacement of native vegetation and disruption of wildlife food chains, with dire consequences for forest-dependent communities such as the Soliga people. These impoverished populations often find their traditional livelihoods under threat, compelling them to migrate and seek new means of subsistence.
The historical context of invasive species highlights a pattern as old as agriculture itself. Humans have long transported plants and animals across natural boundaries for economic, cultural, and aesthetic reasons. However, the scale and speed of these exchanges have skyrocketed, especially during the colonial era and post-World War II globalization, intensifying species introductions across continents and islands alike. This accelerated mobilization is compounded by modern factors such as deforestation, habitat fragmentation, pollution, and climate change, which weaken ecosystems’ inherent resistance to invasions while amplifying the consequences of alien species establishment.
A critical insight from this review is the role of human-induced environmental disturbances as both facilitators and beneficiaries of invasive plant spread. Deforestation and land-use changes disturb native ecosystems’ checks and balances, diminishing natural competitors, predators, and herbivores that otherwise regulate plant populations. Climate change further exacerbates these dynamics by favoring particular invasive species that thrive under elevated temperatures and altered precipitation regimes. In the Amazon, for instance, invasive grasses ignite wildfires that degrade forest canopies, impede native regeneration, and escalate carbon emissions, fueling a feedback loop of environmental degradation.
Paradoxically, rising atmospheric CO2 concentrations create conditions beneficial for woody invasive plants in savannas, where fire suppression and the loss of large herbivores tilt the balance away from native grasses. This shift in plant community composition signals not merely a biological invasion but a fundamental restructuring of ecosystem architecture with broad repercussions for biodiversity, nutrient cycling, and carbon storage. The expansion of these novel ecosystems challenges traditional conservation and restoration paradigms that emphasize returning landscapes to historical baselines.
The researchers emphasize the importance of distinguishing between alien plant species provoking negative impacts—termed invasive—and those that exhibit neutral or even beneficial roles within contemporary ecosystems. As native species decline under pressures from habitat loss and climate change, some alien plants can temporarily fill ecological voids, maintaining ecosystem functions or providing services such as soil stabilization or habitat structure. This nuanced understanding calls for adaptive management frameworks that leverage the ecological potential of certain alien species while controlling those that imperil native biodiversity and local livelihoods.
Despite growing awareness of invasive plants’ complex roles, effective management remains a formidable challenge. Complete eradication efforts are often prohibitively expensive, ecologically damaging, and logistically unfeasible given the widespread extent of invasions. Moreover, invasive plants frequently rebound following removal attempts due to resilient seed banks or reinvasion from neighboring areas. The researchers advocate for nature-based solutions that integrate biological, ecological, and social dimensions to control invasions sustainably, such as reintroducing native large herbivores like elephants or buffalo that naturally suppress invasive plant populations through grazing.
In regions where invasive plants have irreversibly replaced native species, or where resources for rigorous management are limited, a pragmatic approach involves adapting to the new ecosystem realities. Local communities exemplify innovative strategies, utilizing invasive plant species for economic benefit and cultural practices. Crafts and furniture made from Lantana, biochar production from Prosopis juliflora, and commercial products derived from water hyacinth showcase human resilience and creativity in response to shifting ecological conditions. These grassroots adaptations underline the significance of community engagement and indigenous knowledge in designing context-sensitive management plans.
The study sheds light on the profound socio-ecological interdependencies that invasive species create, transforming not only landscapes but also human-nature relationships. In regions of high reliance on ecosystem services for food, medicine, and cultural identity, invasive plants can drive wildlife conflicts, jeopardize food security, and necessitate livelihood shifts. Understanding these dynamics through interdisciplinary inquiry is essential for crafting policies that balance conservation goals with social justice and economic development.
Looking ahead, the surge in global connectivity, climate volatility, and environmental degradation signals that invasive species issues will intensify unless addressed through coordinated, science-informed strategies. Continuous monitoring, integrative modeling, and collaborative research spanning multiple countries are imperative to anticipate invasion trajectories and devise effective interventions. The study by Mungi and Svenning marks a pivotal contribution to this endeavor, synthesizing knowledge that can guide policymakers, conservationists, and local stakeholders towards innovative, equitable, and resilient approaches to managing alien plants in the greater tropics.
In conclusion, the interplay of biological invasions, environmental change, and human adaptation reveals the dynamic nature of tropical ecosystems confronting unprecedented challenges. Alien plant species function as both disruptors and potential stabilizers within these evolving landscapes. By embracing complexity and promoting partnership with local communities, this research points toward a future where management of invasive plants aligns ecological integrity with sustainable livelihoods—an urgent mandate as the world navigates the Anthropocene’s uncertainties.
Subject of Research: Not applicable
Article Title: Alien plants and novel ecosystems in the Greater Tropics
News Publication Date: 14-Jul-2025
Web References: http://dx.doi.org/10.1038/s44358-025-00068-3
References: Mungi, N. A., & Svenning, J. C. (2025). Alien plants and novel ecosystems in the Greater Tropics. People and Nature. https://besjournals.onlinelibrary.wiley.com/doi/10.1002/pan3.70073
Image Credits: Ninad Avinash Mungi
Keywords: invasive species, alien plants, greater tropics, Lantana camara, ecological impact, ecosystem change, climate change, biological invasion, nature-based solutions, local communities
