Seed dispersal and site characteristics influence germination and seedling survival of the invasive liana Euonymus fortunei (wintercreeper) in a rural woodland

Abstract

The invasive liana Euonymus fortunei (Turcz.) Hand.-Maz. (wintercreeper) is an emerging invader that through monodominance of woodlands can drastically reduce native species diversity and alter nutrient cycling. We studied how the vegetation and soils of invaded (INV), “native” (NAT), and wintercreeper removal (REM) site treatments influenced seed germination and seedling survival of this invader. The effect of aril (with vs. without) was also tested for wintercreeper seeds under field and in vitro conditions as a proxy for gravity vs. animal dispersal of seed, respectively. Germination was significantly delayed for seeds sown with an aril (vs. without), as well as those sown in INV soils (vs. NAT or REM), but neither site nor aril affected total germination. The proportion of germinated seedlings that survived after the first winter was significantly different based on site (p = 0.054) and aril (p = 0.071) treatments, with lower survival resulting from seeds sown without arils, and for seeds sown in INV sites. Magnesium (Mg) concentrations were significantly higher among INV soils (vs. NAT) and provide further support that wintercreeper is a driver of soil nutrient change. Our findings that aril-enclosed (gravity-dispersed) seeds yielded greater survival, despite being locally dispersed within invaded sites (where survival was lowest), support the historically slow rate of spread for this species.

Genetic analysis of invasive spread of wintercreeper (Euonymus fortunei), a popular ornamental groundcover

“…Taken together, the knowledge of what genotype or genotypes are actually invasive is extremely helpful in limiting the further spread of E. fortunei in the United States. nurseries (Mattingly 2016;Rounsaville 2017;Tanner et al 2017). This cultivar is noted for its distinct purple-colored foliage and rapid growth; it also most closely resembles the morphology and purple/reddish coloration of Euonymus that has invaded wooded areas (Rounsaville 2017;Sink et al 2000).…”

“…nurseries (Mattingly 2016;Rounsaville 2017;Tanner et al 2017). This cultivar is noted for its distinct purple-colored foliage and rapid growth; it also most closely resembles the morphology and purple/reddish coloration of Euonymus that has invaded wooded areas (Rounsaville 2017;Sink et al 2000).…”

“…A member of the Celastraceae (spindle-tree family), E. fortunei is native to China, Korea, and northern Japan (Rounsaville 2017). Dirr (1998) described three different species varieties and 52 cultivars that vary largely in terms of leaf morphology and size (including variegation).…”

“…The capsule dehisces to reveal between one and four seeds covered in an orange aril (Figure 2C). Seeds are facultatively dormant, being able to germinate with or without cold stratification, and can have a germination rate of up to 98% (Dirr 1998; Rounsaville et al 2018). The plant is also able to reproduce vegetatively through fragment propagules that are broken off during high winds or storms.…”