King's College London – AlienImpacts

January 29, 2026

Neighbours Matter More Than Herbivores in Grassland Chemistry

How competition, not consumers, shapes plant chemistry

Plants are chemical powerhouses.

They make a huge range of chemicals. Some help them grow, others protect them from pests or stress. For years, scientists have thought these chemicals mainly evolve because of herbivores and diseases. But new research suggests something different: the plants growing next to you might matter more than who is eating you.

A study looked at two species in a long-term grassland experiment in Minnesota: Andropogon gerardi (also known as big bluestem, which is a tall grass) and Lespedeza capitata (roundhead bush clover; a nitrogen-fixing legume).

The team tested how these plants’ chemistry changed when they grew alone or in mixed communities, and when insect and fungi enemies were either present, or reduced with pesticides.

The findings were surprising. Both species grew better when pests were reduced, but their chemical make-up didn’t always change.

For A. gerardi, the chemistry stayed almost the same no matter the treatment. This suggests the grass relies on built-in defences rather than changing its chemistry when stressed.

L. capitata, on the other hand, reacted strongly to its neighbours. When surrounded by other species, it produced more amino acids and phenolic compounds – signs of stress – and less sugar. This means competition, not herbivory, was the bigger challenge.

Why does this matter?

First, it questions the old idea that herbivores are the main reason plants have such diverse chemistry. At least in the short term, who you grow next to can be more important. Second, it shows species respond differently. The grass seemed to thrive in mixed plots, while the legume struggled – both in growth and in chemical balance.

These differences could affect whole ecosystems, from nutrient cycling to how plants interact with insects.

The study also shows how complex plant responses are. Chemicals that dissolve in water and those that dissolve in fats behaved differently, and overall pest damage was low in the year studied. Even so, the evidence points to neighbours as key drivers of chemical change.

For ecologists and land managers, predicting how plants respond to climate change and biodiversity loss means looking beyond herbivores. As plant communities shift, their chemistry will shift too – and that could change how ecosystems work.

Future research should test more species and sample over time to catch short-term changes. For now, this study offers a simple lesson: in the chemical lives of plants, competition can matter more than consumption.

Read more:

Joshua I Brian, Adrien Le Guennec, Elizabeth T Borer, Eric W Seabloom, Michael A Chadwick, Jane A Catford, Plant neighbours, not consumers, drive intraspecific phytochemical changes of two grassland species in a field experiment, AoB PLANTS, Volume 17, Issue 6, December 2025, plaf071, https://doi.org/10.1093/aobpla/plaf071

Article originally posted on KCL’s Spheres of Knowledge

January 19, 2026January 19, 2026

Understanding Alien Plant Invasions

Alien plants are everywhere – but not all invaders behave the same

a group of yellow flowers — Photo by Brittany Lee on Unsplash

Alien plant invasions are accelerating worldwide, posing serious threats to biodiversity and costing billions in management. A recent study – led by David Gregory as part of his Masters at King’s and in collaboration with Matt White from the Victorian government – sheds light on how these invasions unfold across landscapes and why growth form matters when predicting and managing risk.

The research, conducted in Victoria, Australia, analysed data from more than 7,600 vegetation surveys spanning five decades. It found that 69 per cent of surveyed plots contained alien species, which made up 22 per cent of all recorded plant species. Forbs (broad-leaved herbs) were the most common invaders, followed by graminoids (grasses and similar) and woody plants. Yet the patterns of invasion were far from uniform.

Using boosted regression trees – a machine-learning approach well suited to ecological data – the team modelled how environmental, biotic and human factors influence both the presence and dominance of alien plants. Abiotic conditions, particularly temperature and rainfall, emerged as the strongest drivers overall, explaining up to 76 per cent of variation in invasion risk. Summer maximum temperature was a consistent predictor across all growth forms, with occupancy rising sharply above 23°C.

Human activity also played a major role. Areas with intensive land use, such as urban centres and agricultural zones, showed the highest levels of invasion. Alien forbs and graminoids were especially prevalent in these disturbed landscapes, often reaching more than 70 per cent cover in towns and cities. Alien woody plants were less widespread but still more likely to occur in urban areas than in intact forests.

Interestingly, the relationship between vegetation cover and invasion differed by growth form. Alien forbs and graminoids were more likely to occupy sites with high vegetation cover, but their proportional cover tended to decline as native vegetation increased – a sign of strong competition. Woody invaders, by contrast, were negatively associated with woody vegetation cover, suggesting that dense tree cover offers resistance to colonisation.

Spatial predictions confirmed these trends. Alien forbs had a high probability of occurring almost everywhere, even at higher elevations, though their cover remained low in alpine regions. Alien graminoids were largely confined to lowland areas dominated by human activity, while woody invaders were the most restricted, reflecting lower seed dispersal and availability and lower habitat suitability.

A global challenge

These findings resonate far beyond Australia. Invasive alien plants are among the top five drivers of biodiversity loss globally, according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES).

They disrupt ecosystems, alter fire regimes and threaten food security. Economic costs are staggering – estimated at more than US$400 billion annually worldwide – and rising as trade and travel expand. Climate change compounds the problem by creating conditions that favour invaders, while land-use change accelerates their spread.

Understanding invasion dynamics at scale is therefore critical for global conservation strategies.

The implications for management are clear. Maintaining and restoring native vegetation is critical to limiting alien plant dominance, particularly after disturbances such as wildfire – a growing risk under climate change. Urban expansion and agricultural intensification will likely increase invasion pressure, making strategic land-use planning essential. Grouping species by growth form, as this study does, offers a practical way to prioritise control efforts without building hundreds of single-species models.

Alien plant invasions are complex, shaped by climate, land use and ecological interactions. But by recognising both shared drivers and growth-form-specific patterns, we can design more effective strategies to protect ecosystems. Growth-form-based models provide a tractable, widely understood tool for science and policy – a step towards smarter, landscape-scale management of one of the most pressing environmental challenges of our time.

Read more:

Gregory D, White M, Catford JA (2025) Similar drivers but distinct patterns of woody and herbaceous alien plant invasion. NeoBiota 103 31–52. https://doi.org/10.3897/neobiota.103.164914

February 13, 2023March 14, 2023

Beyond Triffids: Plants without Prejudice – collaboration with artist Léonie Hampton

We’re excited to welcome Léonie Hampton from the artist collective Still Moving to our group and department for a 6-month artist residency.

Together, we will develop a project exploring perceptions of human and plant “nativeness” to perceive ourselves in relation to biodiversity and climate crises.

_{Activate from the series ‘Beyond Triffids: Plants without Prejudice’ 2023 by Léonie Hampton.}

Beyond Triffids: Plants without Prejudice

Invasive alien species are recognised as one of the greatest threats to global biodiversity, their invasion facilitated by, and compounding impacts of, climate change.  Within ecology and conservation biology there is a heated debate about whether alien plant invasions are good or bad for biodiversity. Do human-introduced alien species increase diversity and compensate for native species loss? Or are alien plants a major threat to biodiversity, warranting active management and restrictions on trade and travel?

Through the lens of alien plants we will particularly focus on perceptions of “nativeness” – both human and plant. Our interdisciplinary approach – co-created between arts, science and humanities – will challenge and interrogate understandings and value judgements, and how these values may need re-evaluation in light of biodiversity loss and migration.

Just as speculative fiction creates the potential, far off in space, where we might see ourselves more clearly, this creative collaboration will work with the perceptions and values of plants to perceive ourselves in relation to our urgent biodiversity and climate crisis.

Our first public outreach event through this collaboration will be held at the Thelma Hulbert Gallery in Honiton on 4 March: Climate Conversations & Honiton Seed Swap. This will take place on the final day of Léonie’s exhibition “A Language of Seeds“.

The residency is funded by King’s Culture and supported by our ERC project AlienImpacts. More about this collaboration and five others supported by King’s Culture can be found here.