The aliens have landed! What are the justifications for ‘native only’ policies in landscape plantings?

Kendle, A. D., & Rose, J. E. (2000). The aliens have landed! What are the justifications for ‘native only’ policies in landscape plantings?. Landscape and urban planning, 47(1-2), 19-31. PDF.

Summary

Kendle and Rose (2000) draw on cases from the UK to argue that native species may not always be superior to exotic species. There are many definitions for ‘native’, but each has biases in the timescale, boundaries, and human agencies they are defined by. Apart from this complication in defining ‘native’, some native species are invasive (e.g. Molinia careulea, Ulex spp. in the UK) and some exotic species play important economic and ecological roles by providing food sources, providing habitat, and stabilizing disturbed areas. Many argue that native species are less likely to be invasive, they conserve genetic diversity, and support more species interactions compared to exotics. Kendle and Rose (2000) point out examples that defy these assumptions, arguing that planting local species is important for the stated reasons, but those same reasons do not invalidate the role that exotic species play in rapidly changing landscapes.

Take home points

• Different cultural, political, and historical values factor in to the many definitions of a native species, which convolute the value in distinguishing between 'native' and 'exotic'.

• There are several examples in which native species may be ecologically harmful, and exotic species beneficial. 

Management implications

• Consider how the traits of different species fulfill your goals when making conservation and restoration plans. 

• Plant local species first, but management success may require planting exotic species depending on access to resources. 

Keywords

Impact Study; Review; Invasive Plant; Terrestrial Habitat