In Hungary, large abandoned agricultural areas have been invaded by the non-indigenous common milkweed (Asclepias syriaca L.). This species hinders the regeneration of sandy oldfields to open sand grassland (Pannonic sand steppes - Annex I 6260 habitat type). Glyphosate application is a cost-effective control method that helps avoid soil surface disturbance and subsequent germination of milkweed seeds in the soil. However, it affects non-target plant species negatively, as well. In our study we explored the effects of the treatment on the non-target vegetation. Glyphosate spraying was applied to three oldfields in the Kiskunság National Park to control vigorous stands of A. syriaca in July 2006. Shoot number of A. syriaca and percentage cover of plant species were estimated in 1m2 permanent plots before and after treatment (June 2006 and June 2007). Elimination of common milkweed was successful in the short term. Multivariate analysis showed a general shift of species composition following herbicide spraying. The share of summer annual herbs and grasses increased significantly, while perennial grasses and herbs decreased in cover. A significant decrease in the average cover of sand grassland specialist species were detected, while weedy species increased in their abundance. The revealed changes showed that it is an effective way to control common milkweed in the short term. However, it disturbs the underlying vegetation so that it relapses succession back to an earlier stage, rich in annual species in the case of the open patch types, while helps to proceed succession when the vegetation has been closed by clonal grasses.
Szitár K, Török K: Short-term effects of herbicide ... (2008)
Szitár Katalin, Török Katalin
Short-term effects of herbicide treatment on the vegetation of semiarid sandy oldfields invaded by Asclepias syriaca. L.
Extended abstract in the Proceedings of the 6th European Conference on Ecological Restoration, 8-12 September 2008, Ghent, Belgium. 1-4.