On Sunday 26 February the Association de Botanique et de Mycologie de Sainte Maure de Touraine held its first outing of the year. The aim was to survey a site and conduct a fairly informal workshop on identifying plants when they are just leaf rosettes. Dominique Tessier and François Botté led the outing and prepared a very useful draft list of species, along with photographs of many.
The two sites we visited were on les Hauts de Draché and both were abandoned vineyards that had been compulsorily purchased along the route of the new high speed train line between Tours and Bordeaux. A corridor to protect biodiversity has been created along this route as a means of mitigating the fragmentation of the habitat by the works. The first of the sites we visited was acid sandy soil, the second was flint-clay. Underlying both the sites is a bedrock of yellow tuffeau (limestone). With the abandoned vineyards there is a bit of a dilemma in terms of how they are managed in the future. Does one resurrect them as organically managed vineyards or is there another solution that will be just as good for biodiversity?
|François pulling a Wild Onion Allium vineale (Fr. Ail des vignes) apart bit by bit to demonstrate all the diagnostic characters needed to identify the species.|
The obvious choice is to manage them as vineyards, but the site is on the edge of the area covered by the Conservatoire d'espaces naturel Centre-Val de Loire, meaning there is a logistical and resources issue (ie it is too far from the single naturalist on the staff responsible for this site, who is based in Orléans, and has other sites they must manage). One of the sites has a tiny parcel of privately owned vines neighbouring it, and it is possible that the farmer might be engaged to manage the Conservatoire's sites, but this would take a couple of years of negotiation and a certain amount of supervision, as the site must be managed for biodiversity first and wine second.
|Here's what happens if you simply mow, or do nothing and allow natural regrowth on sandy soil. In the foreground, nothing but dense grass, in the background, scrub. This is right beside the sandy site shown above.|
On the sandy site the decision has been taken to manage it as a cultivated parcel. Studies comparing annually harrowed sandy parcels with roadsides mown late in the season have shown that annual harrowing of sites with light soil like this benefits biodiversity and that annual mowing, no matter when in the season, is the least effective management technique. The reason is that grass species will dominate and prevent the germination of arable 'weeds' (many species of which are now rare and declining). The seeds of these 'weeds' provide summertime food for many birds.
|A fossil sea urchin, found amongst the vines on the flint-clay site.|
As is common in the Loire Valley, the harrow had brought some fossils to the surface. Typically in this sandy soil the fossils are ancient sponges. On the other site, with flint-clay soil, we found fossil corals and a sea urchin.
|The lichen Cladonia sp growing in association with the dead or sawn off vines of the abandoned vineyard.|
On both sites one of the plants we recorded was Wild Onion Allium vineale (Fr. Ail des vignes). François gave a demonstration of how to identify this small insignificant looking ancestor of the domestic leek (maybe...). According to him, he once spent three years as a young researcher trying to sort out the taxonomy and phylogeny of the domestic leek and it sent him crazy (I've been wondering what it was...). Leeks are one of those plants whose past is so obscure we cannot say what wild species form its ancestry. Leeks do not occur in the wild, they are an entirely human creation, probably with origins in ancient Egypt. Wild Onion closely resembles a number of other species, but curiously its closest relative, as revealed by chemical analysis, is Ramsons A. ursinum (Fr. Ail des ours), which with its loose inflorescence of white flowers and broad flat leaves looks nothing like its pink bobble flowered, thread leaved cousin.
|A row of abandoned grape vines being taken over by Silver Birch Betula pendula (Fr. Bouleau pendant) and Aspen Populus tremula (Fr. Peuplier tremble) trees.|
At the second site one of the most striking things we encountered was masses of the lichen Cladonia sp growing in rows, reflecting where the rows of vines used to be.
|A small parcel of vines near the high speed train line that is being maintained.|
These compulsorily purchased sites have to be surveyed before purchase because the extent of the area purchased is dependent on how many protected species are recorded there. The landowner is compensated based on the potential use of the property, not the actual use. Once purchased, the State has an obligation to maintain the biodiversity and must monitor the site for 50 years. Because of the chronic lack of resources, they rely on volunteer organisations like ours to do the surveys. Over a fifty year period there will be considerable problems with continuity of record keeping and management, due to the new landowner being a public body that is merged or divided as government policies change.
Here is a link to André's photos of the outing, with a couple of me looking like I know what I'm doing! (green waterproof, blue glasses) plus Dominique and François' draft list and specimens at the end.