Taller trees with higher seed output are more likely to invade temperate forests in Patagonia

Tree invasions threaten native forests worldwide, yet little is known about how to prevent this process. To detect these invasions early it is vital to anticipate potential invaders: identifying traits of successful tree invaders in forests is key. The Pinaceae family is an ideal study system to identify which traits favor tree invasions in forests because many of its species were planted in forests across the world several decades ago and they include many plant traits potentially associated with invasion success. For 45 introduced Pinaceae species planted 100 years ago on an island dominated by native forests in Patagonia, and for the subset of 24 species naturalized on this island, we evaluated the relationship between traits (seed mass, maximum height, wood density, juvenile period and interval between large seed crops) and invasion incidence (whether a species has become invasive or not) or extent (number of invaded transects across the study area). We found that invasion incidence and extent increased with maximum height, decreased with seed mass, juvenile period, and interval between large seed crops, and was unaffected by wood density. These results were similar for both introduced and naturalized species pools. Taller trees with smaller seeds, which start producing seeds earlier and continuously, will produce more seeds that can disperse further (especially if released from greater heights), increasing the probability of finding suitable microsites for seedling establishment, and accelerating population spread. In this study system, we conclude that future introductions of non‐native tree species to forests should focus on species with lower invasion risk: those with lower maximum height, bigger seeds, longer juvenile periods, and longer intervals between large seed crops.