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ARTICLE IN PRESS
Ecological Engineering xxx (2011) xxx–xxx

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Ecological Engineering
journal homepage: www.elsevier.com/locate/ecoleng

Evaluation of the most common engineering methods for maritime cliff-top vegetation restoration
Jérôme Sawtschuk ∗ , Sébastien Gallet, Frédéric Bioret
Institut deGéoarchitecture, Université de Bretagne Occidentale, CS 93837 29238 Brest Cedex 3, France

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a b s t r a c t
In Brittany (France), impacts of human activities, especially those caused by tourism, have progressively resulted in the alteration of coastal cliff-top heathland and grassland vegetation in most popular tourist sites. In this framework, in many sites, access to degradedareas has been restricted to stop degradation, while restoration operations have been carried out, mostly based on the natural resilience of the vegetation. In addition, various ecological engineering techniques aimed at enhancing the re-vegetation of the worst degraded areas have also been implemented. This study assesses experimentally various combinations of the most classical restorationtechniques in use in cliff-top restoration operations as geotextile, soil decompaction, turfing, harvested biomass or litter transfer, at different environmental exposures in two sites of Brittany (Crozon peninsula at the far west end and Belle-Île in the south). These investigations highlighted significant differences between methods. Litter treatment appeared to be one of the most efficient techniques,with geotextile and harvested biomass. Turfing, although effective, does not justify its use in comparison with the previous less destructive techniques. Association between techniques especially with geotextile highlighted beneficial complementarities. Experiments set up in different stress expositions show a global negative effect of stress exposure on the efficacy of restoration techniques. ©2010 Elsevier B.V. All rights reserved.

Article history: Received 9 June 2010 Received in revised form 13 December 2010 Accepted 14 December 2010 Available online xxx Keywords: Maritime cliff-top vegetation Engineering methods Stress exposure Heathland Grassland Restoration success

1. Introduction Atlantic ocean-exposed cliff-tops, out of reach of the direct impact by sea water, support naturalgrassland and heathland depending on the degree of exposure to salt spray (Malloch, 1972; Bioret et al., 1991; Doody, 2001). In Brittany (Western France), where they constitute one of the main tourist features, they provide substantial economical resources (Voase, 2002). As observed in many tourist sites across France, the increase of human visitation has led to the degradation of these rare andscattered ecosystems (Kerbiriou et al., 2008). Various operations aimed at restoring the worst degraded areas have been started in recent decades. For example, 36 cliff-top vegetation-dedicated restoration operations were identified along the French Atlantic coast. Most of them have relied on the use of spontaneous succession as a restoration tool (Gallet et al., 2008). Analysis of long-termvegetation monitoring on some of these sites allowed to investigated methods efficiency and showed that spontaneous succession is efficient for maritime

∗ Corresponding author at: Institut de Géoarchitecture, Université de Bretagne Occidentale, 6 avenue le Gorgeu, CS 93837 29238 Brest Cedex 3, France. E-mail addresses: sawtschuk.jerome@gmail.com, sawtschuk@univ-brest.fr (J. Sawtschuk). 0925-8574/$ –see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ecoleng.2010.12.019

cliff-top vegetation restoration and should be used wherever possible (Sawtschuk et al., 2010). On some places, this passive method led, after 5 years, to results similar to those produced by active methods as turfing (Sawtschuk et al., 2008), as underlined by different authors for others spontaneous...