The use of glyphosate for Carpobrotus eradication in sand dune ecosystems: evaluation of the potential effects on the reintroduction of native plants

Abstract

[EN] Glyphosate application avoids some problems associated with manually controlling Carpobrotus. However, before it can be extended, we must understand whether residual glyphosate affects the restoration of natural vegetation by sowing or planting. Thus, we sprayed glyphosate on plots with 100% Carpobrotus coverage at 10 times the maximum recommended dose (4 g/m(2)) and directly on sand at 0.3 and 4 g/m(2). Sand, sifted sand without Carpobrotus litter and sand with Carpobrotus litter were subsequently collected 15, 30, and 60 days after applications, and were used as substrates to evaluate seedling emergence of four native dune species sown in trays. We also assessed the development of two species when grown in pots. Seedling emergence of M. marina, L. creticus and O. ramosissima was not affected in sand without Carpobrotus litter; A. arenaria emergence was reduced by 35%. Seedling emergence of four dune species was inhibited when glyphosate had been directly sprayed on sand. Effect of dose and time after spraying was observed. The presence of Carpobrotus litter reduced the emergence of L. creticus, O. ramosissima and A. arenaria, and inhibition seemed be caused by the allelopathic properties of the Carpobrotus litter. No significant effects of glyphosate spraying were observed in growth tests.