Biotropica | 2019
Plant competition as a mechanism of invasion on islands: Revisiting the conclusions of Kuebbing and Nuñez (2016)
Abstract
wileyonlinelibrary.com/journal/btp Biotropica. 2019;51:316–318. © 2019 The Association for Tropical Biology and Conservation Invasive plants disrupt native plant community dynamics, ecosystem function, agriculture, and forestry, globally costing billions of dollars in management each year (Pimentel, Zuniga & Morrison, 2005). Identifying the mechanisms underlying invasive plant establishment and native plant decline remains a central goal in ecology. A recent metaanalysis highlighted the widespread evidence that plant–plant interactions are involved in plant invasion dynamics (Kuebbing & Nunez, 2016). In particular, it was shown that under experimental conditions, native plants were more suppressed in growth than nonnative plants when grown with nonnative neighbors. Moreover, native neighbors tended not to suppress the growth of nonnative focal plants at all (effect size overlaps with zero). These results suggest that native plants are weak competitors compared to nonnative plants, suggesting that invasive plants displace native plants by outcompeting them. For biodiversity hotspots, such as insular islands, plant invasions are particularly devastating and are the primary drivers of native plant declines (CaujapeCastells et al., 2010). Identifying mechanisms of plant invasions on islands will not only improve management efforts by targeting the most critical processes of invasive species success, but it can also shed light on predicted inherent differences between island and continental plants, the socalled “island rules” (Patino et al., 2017). For example, low species richness on islands could result in the availability of niche space, which when filled by fast growing and vigorous invasive species could lead to the displacement of native plants that are outcompeted by invasive species (Simberloff, 1995; Stachowicz & Tilman, 2005). To assess whether competition effects of nonnative on native plants are generally stronger on islands than continents, we reanalyzed the Kuebbing and Nunez metadataset after adding the additional variable of site (island vs. continent). Searches on Web of Science (using the same keywords as Kuebbing & Nunez, 2016 with the addition of “island”) revealed no additional studies testing plant competition on islands published since 2016. In addition, we perused all publications that have cited Kuebbing and Nunez (2016), none of which provided new experimental tests of competition on islands. Thus, our new analyses were conducted on the metadataset published by Kuebbing and Nunez (2016). After reviewing the full metadataset, we determined that 10 of the 83 publications were conducted on islands (Britton, Received: 11 October 2018 | Revised: 13 February 2019 | Accepted: 14 March 2019 DOI: 10.1111/btp.12659