How the Environmental Humanities Are Reshaping Invasion Science
Imagine a world where cane toads march relentlessly across Australian landscapes, where prickly pear conquers vast territories, and where crocodiles reclaim waterways they once vacated. These aren't mere ecological incidents; they are profound cultural stories about how we relate to nature, about our fears of the unfamiliar, and about what we value in the natural world.
Introduced in 1935 to control beetles, these amphibians have become a symbol of unintended ecological consequences.
This cactus species transformed over 240,000 km² of Australian land before biological control was established.
For decades, scientists have studied "invasive species" primarily as biological problems to be solved through eradication and control. But what if we've been missing a crucial piece of the puzzle? What if the very language of "invasion" reflects deep-seated cultural anxieties rather than objective ecological reality?
A revolutionary collection of essays titled Rethinking Invasion Ecologies from the Environmental Humanities, edited by Jodi Frawley and Iain McCalman, challenges us to reconsider biological invasions through a more nuanced lens.
This emerging perspective argues that nature cannot be separated from culture, history, and human values. As historian Alison Bashford notes, this work represents "a major turning point" in how we understand relationships between ecology, history, and politics 7 . The environmental humanities approach doesn't discard scientific understanding but enriches it by asking different questions: Why do we fear some newcomers and welcome others? How do our cultural frameworks shape which species we label as "invaders" and which we protect as "native"? This article explores how bridging scientific and humanistic approaches offers more effective and ethical ways to navigate our increasingly mixed-up biological world.
The environmental humanities represent an interdisciplinary field that brings together history, philosophy, cultural studies, and ethics to examine environmental issues. Unlike traditional sciences that often treat nature as separate from human culture, this approach recognizes that our understanding of nature is always filtered through cultural frameworks, values, and histories.
This perspective reveals that our language about introduced species often carries unexamined cultural baggage. The very term "invasion" evokes military metaphors, framing species as enemies to be defeated. As one researcher notes, this can reflect a form of "ecological xenophobia" that may say more about human fears of the foreign than about actual ecological impacts 1 .
Interdisciplinary Approach
Connecting ecology with humanitiesTraditional invasion biology often draws clear lines between "native" species (which belong) and "invasive" ones (which don't). The environmental humanities complicate this binary by showing that:
While the environmental humanities provide crucial conceptual frameworks, understanding real-world impacts requires rigorous scientific investigation. A compelling experiment conducted in Brazil examined how the invasive ginger lily (Hedychium coronarium) affects water cycles in riparian forests—critical ecosystems along waterways that provide numerous ecological services 8 .
Researchers designed a carefully controlled study to measure evapotranspiration (ET)—the process by which water moves from soil and plants into the atmosphere—under different invasion scenarios. They created three distinct experimental treatments using specially designed lysimeters (containers that measure water balance):
Containing only H. coronarium
Featuring four native riparian species
Combining both invasive and native species
The experiment ran for 14 months in greenhouse conditions, with pressure transducers recording water levels every 15 minutes to calculate daily evapotranspiration rates across seasonal variations 8 . This extended timeframe allowed researchers to capture how water use changed with temperature fluctuations and different growth patterns.
The findings demonstrated that invasion by H. coronarium significantly alters hydrological processes, but not necessarily in the ways researchers might have predicted:
| Treatment | Minimum ET (mm/day) | Maximum ET (mm/day) | Accumulated ET (mm) |
|---|---|---|---|
| Invasive (H. coronarium only) | 0.59 | 17.16 | 2,172.53 |
| Native species only | 1.07 | 18.27 | Not reported |
| Mixed (invasive + native) | 0.99 | 18.50 | 2,540.16 |
| Source: Adapted from Pimenta et al. (2023) 8 | |||
Evapotranspiration Patterns
Visualization of water cycle impactsThe data reveals several important patterns. The monodominant invasion scenario showed the lowest minimum and maximum daily ET values, as well as the lowest accumulated ET over the study period. This suggests that when H. coronarium completely replaces native vegetation, it reduces the total amount of water returned to the atmosphere through plant processes.
Perhaps counterintuitively, the mixed community (containing both native and invasive species) showed the highest evapotranspiration rates. Researchers attribute this to the "combination effect" where the invasive ginger lily adds its water use to that of the native trees rather than replacing them. In natural settings, this mixed scenario might represent an early stage of invasion, while the monodominant scenario reflects a later stage after natives have been eliminated 8 .
| Treatment | Temperature Range (°C) | Correlation (ρ) with ET |
|---|---|---|
| All treatments combined | 16.5-30.5 | 0.49 (moderate) |
| Source: Adapted from Pimenta et al. (2023) 8 | ||
This experiment demonstrates that invasive species impacts are neither simple nor uniform. The ginger lily's effect on water cycles depends critically on the context of invasion:
Initially increase water loss to atmosphere
Reduce overall water consumption
Potential impact on local rainfall patterns
The researchers conclude that "the decreased evapotranspiration in monodominant stands reflects a decreased amount of water in the air which consequently decreases the rainfall, affects the energy balance, and ultimately changes the climate along time and space" 8 . This illustrates how a single species introduction can trigger cascading effects throughout ecosystems, potentially altering fundamental processes like the water cycle.
Contemporary researchers investigating biological invasions employ an increasingly sophisticated array of technologies that allow them to detect and monitor species with unprecedented precision and scale. These tools range from molecular techniques to remote sensing, each providing unique insights into how species move and interact in changing environments.
| Tool | Function | Application Example |
|---|---|---|
| Environmental DNA (eDNA) | Detects genetic traces left by species in soil, water, or air | Monitoring invasive rodents on islands without trapping 5 |
| Lysimeters | Measure evapotranspiration by tracking water loss from contained systems | Quantifying water use differences between native and invasive plants 8 |
| Gene Drive Technology | Genetically modifies populations to reduce reproductive success | Experimental approach for potentially eliminating invasive rodents 5 |
| Metacommunity Theory | Analyzes how dispersal between habitats structures ecological communities | Understanding why some communities resist invasions while others succumb |
| Resurrection Ecology | Revives dormant stages from sediment to study historical populations | Tracking how species have evolved in response to past environmental changes 6 |
Each of these tools exemplifies how scientific innovation continues to transform our understanding of biological invasions. The emergence of eDNA analysis is particularly revolutionary, enabling researchers to detect species at extremely low densities—crucial for early intervention when invasions are most manageable.
This method has proven especially valuable in vulnerable habitats like islands where traditional monitoring might be intrusive or impractical 9 .
Meanwhile, frameworks like metacommunity theory provide conceptual tools for understanding invasions across scales. This approach emphasizes that local invasion success depends not just on conditions in immediate habitat but also on regional processes like dispersal—helping explain why some introduced species remain harmless for decades before suddenly becoming problematic .
The environmental humanities don't offer easy answers to the challenges posed by biological invasions. Instead, they provide more sophisticated questions and a more honest acknowledgment of the complexities we face in a globally mixed world. By recognizing that our responses to "invasive species" are shaped by cultural values as much as ecological data, we can develop more transparent and democratic processes for making difficult decisions about which ecological changes to resist and which to accept.
The scientific evidence clearly shows that some introduced species cause genuine ecological damage—displacing native species, altering ecosystem processes like water cycles, and disrupting ecological relationships that have evolved over millennia 8 . Yet the humanities remind us that ecological purity is illusory in a world where human influences are ubiquitous and many ecosystems now contain mixtures of long-established and more recent arrivals.
Integrated Approaches
Combining science and humanities