La Chassagne d’Onnens
2015
Location: La Chassagne d’Onnens
Dates: from 1st April to 30th September 2015
This year A Rocha took part in preparatory work for the revision of the management plan for the Onnens garide, also known as the Chassagne. This region is the largest area of field and dry pasture in the foothills of the Jura and has a particular significance for the conservation of this type of habitat and the flora and fauna which live there.
Over the past few years the ecological quality of this area appeared to be deteriorating: several species were no longer being reported there, the environment was becoming overpopulated, the brushland was becoming increasingly problematic and a large part of the garide was being overgrown by grass. It was in the context of these criticisms that the Division for Biodiversity and Landscape of the Canton of Vaud, who are responsible for the management of the Chassagne, decided to re-evaluate the site with the aim of adapting the management plan which was set up in 1995. One aspect of the evaluation carried out in 2015 is an inventory of Lepidoptera and Orthoptera. This inventory was entrusted to us as part of the continuing collaboration which has existed between the Division and A Rocha Switzerland since 2012.
The conclusions which can be drawn from these inventories are mixed: some species have supposedly disappeared, for example the Mottled Grasshopper Myrmeleotettix maculatus, or their population has reduced in size. Others, such as the Feathered Footman Spiris striata (in danger of extinction) which have not been noted for more than 14 years, have been found again. Other species again have been counted for the first time or are showing healthier numbers than 20 years ago.
These observations have enabled a first ecological analysis of the management of the site which was established in 1995. From this we can see that the current situation doesn’t guarantee that the particular biodiversity of the Chassagne d’Onnens can be maintained. Nonetheless, this does not mean that what has been done should be called into question, because it has allowed a number of important species to be maintained and to increase in population. However, what is lacking is a more differentiated and less homogenous management which would enable resistance against the two main threats to the site – the spread of brushland and the density of the grasses. A possible way forward is the setting up of a spring pasture to be rotated annually round different areas. In conjunction with mechanical clearing of the bush in limited areas, this technique would enable resisting the growth of the brushland and would encourage flowering plants. Other measures have been discussed and the revision of the plan is now in the hands of the Division for Biodiversity and Landscape with whom we have been able to discuss the maintenance of this very special site in an open and constructive manner.
2015
Location: Jura summer pastures in Vaud canton, at 1000–1400 metres altitude
Dates: 1 April – 30 September 2014.
Download the full report (in French): ARCH-PPS-VD-2014-Rapport.
Summary – In 2014 the dry grasslands survey carried out in conjunction with the Vaud Canton Biodiversity and Landscape Department covered 12 sites in the federal dry grasslands inventory, mainly in summer pasture locations. An assessment was made of the day-flying Lepidoptera and Orthoptera present on the sites. Zones where the initial vegetation showed evidence of significant degradation were also mapped. In total 8 hectares were mapped within the dry grassland areas of which 0.83 hectares (11%) were below acceptable thresholds and 3.87 hectares (46%) were at risk in the medium-term. Despite these findings, the general condition was reasonable and management seems to be appropriate. Nonetheless, there is a trend towards richer high altitude pastures which has been found in most of the Jura mountain area. There are various factors which might explain this development and pasture management is not necessarily one of them. One factor could be the input of nutrients from rain, which increasingly contains nitrogen because of human activity [1]. Based on this work we have proposed steps to restore the initial vegetation. Vaud Canton is in charge of the follow up through agreements with individual farmers.
[1] Mauchamp, L. (2014). Biodiversité et gestion des écosystèmes prairiaux en Franche-Comté. Doctoral thesis, University of Franche-Comté, Environmental and Life Sciences : University of Franche-Comté, 2014, 253p.
June 2014
Location: Vaud Canton
Dates: 1 April – 30 September 2013
Download the public report (in French): ARCH-Rapport-2013_public
Summary – The 2013 study covered 15 dry grassland areas subdivided into 30 sites. It was a continuation of the dry grasslands survey work carried out by A Rocha Switzerland in 2012 and was undertaken in collaboration with the Biodiversity and Landscape Department of Vaud Canton.
On each site a survey was made of day-flying Lepidoptera (Rhopalocera and Zygaena) and of Orthoptera (crickets, locusts and grasshoppers). An assessment of the population of certain target vegetation species was also carried out on specific plots.
These inventories were made as part of a re-assessment of the dry grasslands in Vaud Canton with a view to new land management contracts. Current management of these plots was mainly based on the existing vegetation. In carrying out this work A Rocha Switzerland added new information allowing an improved assessment of the ‘environmental health’ of each plot but also more appropriate management methods.
In addition the inventory of populations of certain target vegetation species has enabled the establishment of a baseline, which is essential for assessing the evolution of a given population over time.