Invasive plants pose a major threat to biodiversity and ecosystem stability. Previous studies have focused on single species invasions. However, little is known about the ecological impact of multiple plant species invading together (i.e. co-invasion of alien plants).

In a study published in Soil Ecology Letters, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences showed that co-invasion had a synergistic effect, fundamentally altering the assembly processes and interactions within soil fungal ecosystems.

The researchers investigated the assembly processes and symbiotic networks of different fungal taxa in soils affected by the co-invasion of four invasive plants, comparing them with non-invaded soils. Soil samples were collected from areas invaded by four co-occurring Asteraceae species (Chromolaena odorata, Ageratina adenophora, Tithonia diversifolia, and Bidens pilosa) and contrasted with samples from non-invaded soils.

The researchers categorized fungi into two groups: conditionally rare and abundant taxa (CRAT) and conditionally rare taxa (CRT). Each group exhibited distinct responses to co-invasion, reflecting different survival and filtering strategies.

They found that plant co-invasion increased the alpha diversity (local diversity) of soil fungi and broadened their ecological niche (i.e. the range of conditions they can tolerate). Although the co-invasion increased the network complexity of fungal communities, it reduced their stability, indicating that invasion poses a threat to the stability of soil microbial communities.

Furthermore, the assembly of fungal communities was found to be primarily driven by deterministic processes such as environmental filtering, rather than random chance. Notably, plant invasion intensified this deterministic control, making environmental factors even more critical in determining fungi survival.

In addition, soil pH and the ratio of carbon (C) to phosphorus (P) were identified as the most important factors shaping the fungal community structure.

“The co-invasion of these plants seems to create a new set of rules for the soil fungal community,” said ZHENG Yulong of XTBG. “By enhancing nutrient utilization efficiency, the invasive plants help the microbial community thrive even under limited resource conditions, which may be a key to their successful invasion.”

Chromolaena odorata, an invasive species. (Image by ZHU Renbin)

Published: 06 October 2025