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Invasive Asclepias syriaca can have facilitative effects on native grass establishment in a water‐stressed ecosystem
Author(s) -
Szitár Katalin,
KröelDulay György,
Török Katalin
Publication year - 2018
Publication title -
applied vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.096
H-Index - 64
eISSN - 1654-109X
pISSN - 1402-2001
DOI - 10.1111/avsc.12397
Subject(s) - biology , stipa , festuca , shoot , grassland , festuca rubra , germination , agronomy , seedling , invasive species , botany , growing season , poaceae
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 invasive Asclepias 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.