Invasive Asclepias syriaca can have facilitative effects on native grass establishment in a water‐stressed ecosystem

Abstract

Question: What is the effect of invasive common milkweed (Asclepias syriaca L.) on the germination and early establishment of native grass species during open sand grassland vegetation recovery in old-fields? Location: Fülöpháza Sand Dune Area, Hungary.Methods: A small-scale experiment was carried out in a sandy old-field infested with Asclepias. We designated 36 2 m × 2 m plots in patches of Asclepias. We seeded two native grass species Festuca vaginata and Stipa borysthenica in 12 plots each (a third of the plots was left unseeded). We applied repeated mechanical removal of Asclepias shoots on half of the plots for two growing seasons. The number and above-ground cover of the two grass seedlings were evaluated for two growing seasons. Results:The number and above-ground cover of Festuca and Stipa seedlings did not increase after applying Asclepias shoot removal during the 2 years of the study. We found lower seedling number and cover of Festuca in plots with Asclepias shoot removal in the second year, when a severe summer drought occurred at the study site.The number and cover of the Stipa seedlings did not differ between plots with Asclepias shoot removal and control plots throughout the experiment. Conclusions: We did not find any negative effects of the presence of the invasiveAsclepias during open sand grassland regeneration in terms of germination and early establishment of the dominant grass species. We even detected a nurse effect of Asclepias on Festuca, where the shade of Asclepias may have mitigated the unfavourable abiotic conditions for Festuca caused by summer drought. This mitigation was not observed in the case of Stipa, which can better tolerate summer droughts. Our results suggest that Asclepias control is not required for a successful open sand grassland restoration in the early phase of vegetation recovery, and restoration efforts should focus on the mitigation of propagule limitation of native grasses. However, further information is needed about the effects of Asclepias on other elements of the biota and in later phases of secondary succession. K E Y W O R D S ecological impact, facilitation, germination, inland sand dune, neighbour effect, nurse plant, propagule limitation, reintroduction, restoration, seeding, tussock grass 608 |

Understanding the Environmental Background of an Invasive Plant Species (Asclepias syriaca) for the Future: An Application of LUCAS Field Photographs and Machine Learning Algorithm Methods

“…Invasion of common milkweed has been linked with decreased levels of native plant species cover [23], shifts of maximum vegetation compositional diversity to larger spatial scales in sand grasslands [24], and lower levels of the functional diversity of spiders [25] in invaded ecosystems. In contrast, Jurová et al [26] did not find any negative effects of common milkweed in soil nematode community, while Szitár et al [27] showed positive effects of common milkweed on native grass survival during summer drought.…”

“…Among the land cover categories of the 2012 CLC database, common milkweed prefers areas with complex cultivation patterns and natural grassland areas. The latter factor is of particular concern, because the natural grasslands that are native to the area have significant conservation value [27]. Common milkweed has been primarily invading disturbed areas, such as abandoned agricultural lands [21].…”

Restoration of native‐dominated plant communities on a Centaurea stoebe‐infested site

“…In contrast, hand pulling of other invasive species may not be effective, especially if a species has a clonal habit. For example, repeated hand pulling of Asclepias syriaca (Common milkweed) over two growing seasons did not eliminate it from a grassland site in Hungary (Szitár, Kröel‐Dulay, & Török, ).…”

Forest type interacts with milkweed invasion to affect spider communities

“…Common milkweed ( Asclepias syriaca ) in Europe spreads aggressively and is found in 11 European countries (Szitar et al ., ). It establishes dense populations in disturbed habitats (Pysek et al ., ; Kelemen et al ., ) and may change the composition of existing vegetation and form novel ecosystems (Kelemen et al ., ; Szitár et al ., ).…”