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Invasive plants are often sold as ornamental garden plants, but how often are species sold in the same locations as where they are invasive? To answer this question, we assessed the geography of ornamental plant sales in the United States in relation to existing invasions and potential invasion risk with climate change. Using a data set of 672 nurseries selling 89 invasive plants, we estimated the distance between nursery sales and invasive species' observed distributions. We also used species range maps to identify nursery sales within current potential invaded ranges, as well as within species' future potential ranges given climate change. Half of the species were sold by a nursery within 21 kilometers of an observed record of invasion. Under the current climate, horticulture could be seeding invasions for 73 of the 89 species studied, and horticulture could facilitate climate-driven range expansion of 25 of 89 species. Our results illustrate risks associated with horticultural introductions of invasive species, providing guidance for regulatory and educational interventions that reduce the spread of ongoing and future invasions. [ABSTRACT FROM AUTHOR]

Due to climate change, plant populations experience environmental conditions to which they are not adapted. Our understanding of the next century's vegetation geography depends on the distance, direction, and rate at which plant distributions shift in response to a changing climate. In this study we test the sensitivity of tree range shifts (measured as the difference between seedling and mature tree ranges in climate space) to wildfire occurrence, using 74,069 Forest Inventory Analysis plots across nine states in the western United States. Wildfire significantly increased the seedling-only range displacement for 2 of the 8 tree species in which seedling-only plots were displaced from tree-plus-seedling plots in the same direction with and without recent fire. The direction of climatic displacement was consistent with that expected for warmer and drier conditions. The greater seedling-only range displacement observed across burned plots suggests that fire can accelerate climate-related range shifts and that fire and fire management will play a role in the rate of vegetation redistribution in response to climate change. Tree species that are expanding their distribution in response to climate change could be hindered or facilitated by disturbances. Here the authors analyse forest inventory data from the western US to test the hypothesis that wildfire can facilitate climate-induced range shifts in trees. [ABSTRACT FROM AUTHOR]