Hay Transfer Promotes Establishment of Mediterranean Steppe Vegetation on Soil Disturbed by Pipeline Construction

Abstract

International audienceThe Coussouls de Crau Nature Reserve is a xeric steppe providing a habitat for remarkable animals. Over the past centuries, this steppe has been partly destroyed and fragmented and has been reduced to 9,500 ha out of the 55,000 ha existing before the 16th century. Although this ecosystem is protected, 23 ha of natural habitat were nonetheless destroyed in 2006 during the construction of an underground pipeline. To mitigate potential future damage, an original experiment in restoration ecology was adapted and tested: the technique of hay transfer. The objective of this experiment was to find ways of accelerating steppe vegetation colonization on the soil over the buried pipelines by the reintroduction of steppe species. A factorial experiment was set up to test the effects of habitat characteristics, grazing, and hay transfer. The results obtained for 3 years after the experimentation setup are conclusive in favor of using hay transfer for the restoration of Mediterranean steppe ecosystem. Hay transfer has significantly increased the species richness on restored areas and has allowed the reintroduction of some typical steppe species. Among these species, we found a wide variety of annual grasses which play a key role in the recovery of steppe vegetation and provide food for sheep flocks. Sheep herding must be maintained during the ecological restoration of the herbaceous steppe community, because grazing significantly increases species richness on restored areas without changing species assemblies

A comparison of different soil transfer strategies for restoring a Mediterranean steppe after a pipeline leak (La Crau plain, South-Eastern France)

“…In fact, this steppe vegetation is the result of a regime of particular stress and disturbance induced by the shallow red Mediterranean soil (red fersialitic soil) and by the Mediterranean climate interacting with centuries of sheep grazing and a succession of prairie fires (Devaux et al, 1983;Cherel, 1988;Badan et al, 1995;Henry, 2009). Although this environment is partly protected through the establishment of a National Natural Reserve in 2001 on 7400 ha, extensive areas today require active restoration Coiffait-Gombault et al, 2011;Jaunatre et al, 2014a) as recovery of the steppe vegetation after changes in land use is extremely slow (Römermann et al, 2005;Dutoit et al, 2013a,b).…”

Experimental dispersal reveals characteristic scales of biodiversity in a natural landscape

“…First, the high occurrence of annual species and patchy distribution of serpentine habitat among a nonserpentine matrix is well-suited to testing spatial questions (26) with the hay transfer method (23). Second, our study took place in the California Floristic Province, a global biodiversity hotspot that is threatened by the pervasive invasion of European grasses (26,27).…”

“…We tested the spatial scales at which dispersal and environmental heterogeneity impose constraints on species distributions and diversity using a "hay transfer" technique (23) in serpentine annual plant communities in California. This technique involved vacuuming the seed bank and other loose material from field plots, pooling the material among plots, and then redistributing it.…”

The effects of pipeline construction disturbance on soil properties and restoration cycle

“…Soil compaction and topsoil removal during oil pipeline construction resulted in significant decreases in soil organic matter and nitrogen and phosphorous contents (Woodward 1996). Coiffait-Gombault et al (2011) reported that pipeline construction affected soil C/N, pH, and CaO.…”