Biotic resistance to tropical ornamental invasion

Abstract

Summary We examined invasive, casual (found occasionally outside cultivation) and non‐invasive (found only in cultivation) species to investigate the role of species traits and two forms of biotic resistance (plant neighbours and herbivores) in limiting invasion in Hawaiian lowlands. Seeds of 21 species of common woody ornamentals from three plant families (Acanthaceae, Apocynaceae, Bignoniaceae) that are non‐invasive, casual or invasive in Hawai'i were outplanted at two field sites. We measured germination of seeds and growth and survival of seedlings for 1 year in plots with and without neighbours from the naturally assembled community. The presence of neighbours reduced survival in some species, mostly non‐invasive or casual species, and completely excluded two non‐invasive species from community plots. Damage from the existing community of herbivores was correlated with lower survival in the Acanthaceae and Bignoniaceae, but not the Apocynaceae. Non‐invasive and casual species had lower survival and growth rates than invasive species and lower photosynthetic rates in the presence of neighbours than invasive species. Non‐invasives without neighbours also had lower specific leaf area than invasives and casuals. We found evidence for barriers to invasion in some non‐invasive and casual species, including low growth rate, low survival, or low survival in the presence of neighbours. By contrast, five of the six invasives flowered and three began setting fruit within the duration of the experiment, as did one of the casual species. Synthesis. Our research demonstrates biotic resistance, presumably as a result of competition. Neighbouring plants reduced survival and growth for most species. For non‐invasive species with low survival and growth even without competition from neighbouring plants, this resulted in complete exclusion from community plots or such low growth rates that exclusion over longer time frames was likely. We also provide evidence for traits‐based barriers to invasion in non‐invasive and casual species. However, no single barrier to invasion was shared across all non‐invasive and casual species.

Pre‐damage biomass allocation and not invasiveness predicts tolerance to damage in seedlings of woody species in Hawaii

“…There is evidence that for several other woody plant species in Hawaii, biotic resistance through competition and herbivory (Bufford et al. ), and sterility or lack of pollinator services (Bufford and Daehler ), cause non‐native species to fail.…”

“…Given that this species has not been able to successfully spread well beyond planting sites in Hawaii, despite being able to tolerate herbivory at early growth stages, there are likely other barriers to its invasion success. There is evidence that for several other woody plant species in Hawaii, biotic resistance through competition and herbivory (Bufford et al 2016), and sterility or lack of pollinator services (Bufford and Daehler 2014), cause non-native species to fail.…”

“…, Bufford et al. ). Herbivory, as an important component of biotic resistance, has received considerable attention in the invasion literature (Chun et al.…”

“…Yet, even though non-native plants are transported around the globe at an astonishing rate, only a small percentage of these introduced plants establish sustainable populations and become invasive (Richardson et al 2000), and it remains unclear why some species become invasive while others do not. One reason for failure is biotic resistance, provided by native natural enemies that attack non-native plants in their introduced ranges (Levine et al 2004, Bufford et al 2016. Herbivory, as an important component of biotic resistance, has received considerable attention in the invasion literature (Chun et al 2010).…”

The Effects of Soils from Different Forest Types on the Growth of the Invasive Plant Phytolacca americana

“…Understanding the factors that regulate community invasibility is critical for predicting and controlling plant invasions [3]. Prior studies have shown that successful plant invasions are related to the vegetation characteristics of recipient communities; these characteristics actually affect both the resource availability of habitats and biotic resistance [4][5][6][7][8]. For example, high species diversity sufficiently fills available niches and limits resource supply for invaders, while native species decrease establishment success of invader species that are similar to them in species traits (limiting similarity) [9][10][11].…”