Observations on different post-fire bio-engineering interventions and vegetation response in a Pinus canariensis C. Sm. forest

On the Canary Islands, during the 2007 (30 July - 2 August) wildfire, about 18.000 hectares of forest were destroyed. After the event, to avoid erosion, a series of mixed check dams (wooden elements and stones with a core filled with forest residues) were built in the gullies created by the surface runoff. This first study aims to investigate the different responses of vegetation and its recovery after fire, with three different types of structures. We analyzed the performance and evolution of the mixed check dams nine years after their construction and the post-fire response of vegetation with the different types of bio-engineering techniques applied. The effects of the mixed check dams are expressed in terms of plant density, frequency, and cover both in absolute and in relative terms and the same effects were compared with those of the rocks, check dams, wattle fences, and structure in the surrounding areas. Our observations show that fire adaptation in the Canary Islands vegetation (pyrophyte plants), coupled with selected bio-engineering techniques, facilitated resprouting, seeds germination and a quick restoration of the forest ecosystem. The study confirms that simple, nature-based and low cost bio-engineering measures, which use local materials and are consistent with traditional building experiences effectively contribute to site restoration.