Invasive species rarely move across the landscape as a continuous front; both local and long distance dispersal determine spatial patterns. Plant traits typically used to define dispersal capacity (seed mass and morphology) are inappropriate for predicting the potential spread dynamics of alien species. Infrequent, LDD events, often via non standard means, are often of overriding importance. Postintroduction dissemination by humans, intentional or accidental, is the most significant driver of many plant invasions, and other chance dispersal events are also cru cial. An implication of this is that modeling the spread of alien species assuming 'normal' dispersal is very likely to underestimate spread rates, especially at scales beyond the landscape. Alien plants often produce more propagules in their introduced ranges, which makes LDD more likely than in their native ranges. This improves the capacity of many alien plants to spread across fragmented landscapes and respond to changing environmental conditions.
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