Our ability to predict invasions has been hindered by the seemingly idiosyncratic context-dependency of individual invasions. However, we argue that robust and useful generalisations in invasion science can be made by considering “invasion syndromes” which we define as “a combination of pathways, alien species traits, and characteristics of the recipient ecosystem which collectively result in predictable dynamics and impacts, and that can be managed effectively using specific policy and management actions”. We describe this approach and outline examples that highlight its utility, including: cacti with clonal fragmentation in arid ecosystems; small aquatic organisms introduced through ballast water in harbours; large ranid frogs with frequent secondary transfers; piscivorous freshwater fishes in connected aquatic ecosystems; plant invasions in high-elevation areas; tall-statured grasses; and tree-feeding insects in forests with suitable hosts. We propose a systematic method for identifying and delimiting invasion syndromes. We argue that invasion syndromes can account for the context-dependency of biological invasions while incorporating insights from comparative studies. Adopting this approach will help to structure thinking, identify transferrable risk assessment and management lessons, and highlight similarities among events that were previously considered disparate invasion phenomena.

There is a long history of species being moved around the world by humans. These introduced species can provide substantial benefits, but they can also have undesirable consequences. We explore the importance of human activities on the processes of species dissemination and potential invasions using the Poaceae subfamily Bambusoideae (‘bamboos’), a group that contains taxa that are widely utilised and that are often perceived as weedy. We (1) compiled an inventory of bamboo species and their current distributions; (2) determined which species have been introduced and become invasive outside their native ranges; and (3) explored correlates of introduction and invasion. Distribution data were collated from Kew’s GrassBase, the Global Biodiversity Information Facility and other online herbarium information sources. Our list comprised 1662 species in 121 genera, of which 232 (14 %) have been introduced beyond their native ranges. Twelve (0.7 % of species) were found to be invasive. A non-random selection of bamboos have been introduced and become invasive. Asiatic species in particular have been widely introduced. There was a clear over-representation of introduced species in the genera Bambusa and Phyllostachys which also contain most of the listed invasive species. The introduction of species also correlated with certain traits: taxa with larger culm dimensions were significantly more likely to have been moved to new areas; and those with many cultivars had a higher rate of dissemination and invasion. It is difficult to determine whether the patterns of introduction and invasion are due simply to differences in propagule pressure, or whether humans have deliberately selected inherently invasive taxa. In general, we suggest that human usage is a stronger driver of introductions and invasions in bamboos than in other taxa that have been well studied. It is likely that as bamboos are used more widely, the number and impact of invasions will increase unless environmental risks are carefully managed.

Significance: Governments spend billions of dollars each year managing invasive plant species. Many invasive plants have escaped from pastures and now degrade natural areas and transform ecosystems. New pasture taxa are promoted to help achieve sustainable intensification of agriculture by increasing production without using more land. However, plant characteristics that increase production also increase invasion risk. Combined with inadequate regulation and management to establish large feed-plant populations, new taxa will likely exacerbate problems with invasive species. Livestock production accounts for 30% of the world's land area. Risks associated with invasive feed-plants have been largely overlooked, even by studies explicitly critiquing the environmental risks of sustainable intensification. We suggest a suite of protocols to reduce these risks in sustainable intensification of agriculture.

Grasses using the C₄photosynthetic pathway dominate frequently burned savannas, where the pathway is hypothesized to be adaptive. However, independent C₄lineages also sort among different fire environments. Adaptations to fire may thus depend on evolutionary history, which could be as important as the possession of the C₄photosynthetic pathway for life in these environments. Here, using a comparative pot experiment and controlled burn, we examined C₃and C₄grasses belonging to four lineages from the same regional flora, and asked the following questions: Do lineages differ in their responses to fire, are responses consistent between photosynthetic types, and are responses related to fire frequency in natural habitats? We found that in the C₄Andropogoneae lineage, frost killed a large proportion of aboveground biomass and produced a large dry fuel load, which meant that only a small fraction of the living tissue was lost in the fire. C₃species from the Paniceae and Danthonioideae lineages generated smaller fuel loads and lost more living biomass, while species from the C₄lineageAristidagenerated the smallest fuel loads and lost the most living tissue. Regrowth after the fire was more rapid and complete in the C₄Andropogoneae and C₃Paniceae, but incomplete and slower in the C₃Danthonioideae and C₄Aristida. Rapid recovery was associated with high photosynthetic rates, high specific leaf area, delayed flowering, and frequent fires in natural habitats. Results demonstrated that phylogenetic lineage was more important than photosynthetic type in determining the fire response of these grasses and that fire responses were related to the frequency that natural habitats burned.