Over 70 different orchid species occur in Switzerland, all of them are protected by law. Unfortunately, the last 60 years of overfertilisation and changes in surface use have resulted in present loss of more than 90 % of the orchid habitats in central Switzerland.
Overfertilisation of orchid habitats and the change of use contributet to it mainly. In the few remaining habitats, the greatest threat to the orchids today is caused by collectors, enthusiasts and photographers. Green roofs are known as temporary habitats of extreme conditions and with lesser amount of nutrients. The later and other certain characteristics are also typical for endemic orchid habitats, therefore it is likely that most of the orchid species could survive on roof top greenings. Because of the mobility and vast seed amounts, spontaneus establishment of metapopulations is inherent to these plants. In this study 31 orchid roofs were recorded in Switzerland and considered in detail. All plants established spontaneus.
The very different roofs included a total of 11 different species of orchids. All of them are on the RED LIST of endangered species of Switzerland. The human inaccessibility of these roofs represented ideal conditions for the protection of species. Since a huge threat to orchid species is still present today and green roofs are already proven to serve potential orchid habitats, orchids on the roofs are transferred not only spontaneously but also by green roof executors.
The specialized departement of green roofs of Zurich University for Applied Sciences is concerned with the settlement of orchids on roofs. Specific projects are designed to create roofs which provide ecological niches and breeding platforms for orchids. The first accomplished settlement projects testify that both, the generative propagation of orchids, as well as, the transfer measures were successful. In the potential roof habitats the planted orchids formed new small populations after 5 years.
Keywords: Conservation, edaphon, extensive green roofs, ex-situ, protocorms, mycorrhiza, red-listed orchid, reproduction success, threatened orchid.
Photo: Orchids planted on the rooftop of the hospital (Kantonspital) in Switzerland, courtesy Rafael Schneider.
Who read this to the end may tell us the species of this native orchid on the hospital roof.
Establishment of native orchids on green roofs
RAFAEL SCHNEIDER, STEPHAN BRENNEISEN, BERTIL KRÜSI, YASMINA BOUNAÂJA, PHILIPP RÜEGG, DOVILĖ MALINAUSKAITĖ
Department Life Sciences and Facility Management, Zurich University of Applied Sciences, SWITZERLAND