Invasion potential of herbaceous ornamental perennials in northern climate conditions

Timo Kaukoranta,Terho Hyvönen,Sirkka Juhanoja,Eeva-Maria Tuhkanen

doi:10.23986/afsci.77398

Timo Kaukoranta, Terho Hyvönen + Show 2 more

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https://doi.org/10.23986/afsci.77398

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Abstract

We studied invasion potential of perennial herbaceous ornamental plants in Finland by using their reproduction success as an indicator. Altogether, 220 clones from 166 species were included in the studies. In common gardens, 50% of the species were found to produce seedlings and 75% rhizomes, respectively. Twelve of the clones produced neither seedlings nor rhizomes. Rankings of the invasion potential based on the two reproduction modes did not correlate. The species known for their invasion potential in temperate or cool climates were among the highest ranking seedling producers in the common gardens. In the field experiment, the highest seedling production (73%) was found in the semi-dry moisture regime, followed by the dry (40%) and the moist (27%) regimes. In the greenhouse experiment, 83% of the studied clones and 84% of the species emerged. Temperature sum required for the production of viable seeds for one third of the studied species is reached at least every second year in latitudes 62–63°N. Several perennial herbaceous ornamentals have potential for northward range expansion.

Highlights

In search for new ornamental species, alien species have long been widely introduced outside their native ranges.The wide and repeated introductions increase the likelihood of them escaping from cultivation (Dehnen-Schmutz et al 2007a, 2007b, Hanspach et al 2008, Ööpik et al 2013)
The majority of the species included in the study were found to be capable of producing viable seeds or rhizomes in the northern climate conditions
While the common garden experiments showed mostly similar rankings for the full set of the clones for all cities, the three different types of experiments gave different rankings for the set of clones that were common for all experiments

Summary

Introduction

In search for new ornamental species, alien species have long been widely introduced outside their native ranges.The wide and repeated introductions increase the likelihood of them escaping from cultivation (Dehnen-Schmutz et al 2007a, 2007b, Hanspach et al 2008, Ööpik et al 2013). Ornamentals have been selected for rapid and often vigorous growth, large size, long flowering time, tolerance of competition and survival in physically and biologically adverse environments. These traits characterize successful alien invasive plant species (Klironomos 2002, Lake and Leishman 2004, Anderson et al 2006, Colautti et al 2006, Pyšek and Richardson 2007, Hanspach et al 2008, Küster et al 2008, Fenesi and Botta-Dukát 2010, van Kleunen et al 2010). That generally are not actively selected for in perennial ornamentals, but have been associated with invasiveness in several studies, are the abundant production of seed and rapid germination

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