Happy New Year! I hope everyone had restful and enjoyable holidays. In addition to looking back over the year that just past, a common New Year’s tradition is to make predictions for the coming year. Without going too far out on a limb, one of my predictions for the upcoming year is that the debate over invasive plants will continue to intensify, especially as it relates to Landscape Horticulture. Along these lines, a couple of recent articles by Gregorio Gavier-Pizarro and his colleagues at the University of Wisconsin and the USDA Forest Service caught my eye.
In both studies; “Housing is positively associated with invasive exotic plant species richness in New England, USA” (Ecological Applications 20:7, 1913-1925) and “Rural housing is related to plant invasions in forests of southern Wisconsin, USA” (Landscape Ecology 25:10, 1505-1518), the investigators conducted on-ground assessments of species richness and density of commonly listed invasive plants (e.g., Japanese barberry, Autumn olive, Honeysuckle, Common buckthorn, Multiflora rose) in conjunction with spatial analysis of remote sensing data to examine patterns of invasive spread in the urban/wildland interface. As one would expect, the presence and species richness of the invasives increased with development. An important ‘take home’ message, however, is that disturbance associated with rural housing development and the creation of edges appears to be the biggest driver of invasive species encroachment. That is, land clearing, road-building and other development activities create habitats that are more susceptible colonization – a condition referred to as ‘invasibility’. So whether a particular homeowner plants natives or non-invasive exotics they may still contribute to the expansion of invasive exotic plants in their region by increasing its invisibility.
The other thing that makes this work and related studies significant is that I think we will see a continued shift in the efforts to curtail the expansion of invasive exotic plants. In particular, rural housing development and associated landscape practices will become and increasingly intense front-line in the invasive battle.