Published in Eurorchis no. 14, 2002
Jan van der Straaten, Kees Laarhoven and Willem van Kruijsbergen
Introduction and Problem Definition
Orchis spitzelii is generally considered as one of the rarest European orchids. The distribution within Europe is disjunct. The species can be found only at a few locations; at one single location the quantity of plants can be considerable. Delforge (1994) mentions locations in Slovenia, Switzerland, Austria, Italy, France and Sweden; he is of the opinion that in Spain only O. cazorlensis can be recognised. Locations are also known from Greece, former Yugoslavia, Albania, Morocco, Syria and Turkey. In recent years, new locations have been found in particular in the southeastern part of France. Jacquet (1995), for example, describes locations in the departementes Corse, Var, Alpes-Maritimes, Alpes-de-Haute-Provence, Hautes-Alpes, Dr�me, Is�re, Haute-Savoie and Jura. Probably, the highest number of locations is in the departement Is�re. In the recent distribution atlas of this departement some thirty locations are mentioned (Mus�um d�Histoire Naturelle de Grenoble, 1995).
When we visited for the first time the southeastern part of the Vercors some years ago, we were, indeed, very curious about this rare orchid. Where can it be found? Which biotopes are typical for this species? Is this orchid threatened and from what this turns out? We consider this type of questions the most relevant research topics, as without an adequate knowledge on this point an appropriate protection of this orchid is not possible. Additionally, this is relevant, as the existing literature does not give a clear picture of the biotope requirements of this species. It was not difficult the find the first plants of Orchis spitzelii. Hans Dekker told us, that they could be found on the road shoulder not far away from the Col de l�Allimas in Gresse-en-Vercors. He said us that the species is growing there between Arctostaphyllos uva-ursi; the same description is given in the literature we studied. Indeed, a few plants were growing there in the first weeks of June. However, hardly any Arctostaphyllos uva-ursi could be recognised on these locations.
Publications on Orchis spitzelii provided us with some information regarding biotope requirements. But we could not come to coherent conclusions in this respect. Next year we tried to gain a more clear understanding of the biotope requirements by visiting all places which were more or less similar to the location on the Col de l�Allimas. This brought us some results: five new locations could be found. Furthermore, one of the authors of this article found in the meantime a substantial location in an open forest south of Gresse. We were of the opinion that by doing so, we built up a certain feeling for this species. We used this experience as a basis for further research in the southeastern part of the Vercors in the first week of June 2001. This research has been realised by the authors of this article, Marijke Verhagen, Harrie van Loon, Ton Brok en Mat Crijns. We searched the slopes and open forests by walking a distance of some hundred kilometres on mountain paths in appropriate areas during the first two weeks of June. Finally we thank Hans Dekker for useful comments on a first draft of this article and for helping us with relevant literature.
Results of our Investigations
The results were staggering. In the recent distribution atlas of the departement Is�re the species is mentioned for some thirty locations in 18 plots (Mus�um d�Histoire Naturelle de Grenoble, 1995). Our research was realised in 5 plots in the southeastern part of the departement. We found the species there on 42 locations, which is considerable more than is mentioned in the atlas for the whole departement. How is it possible that we could find so many locations? In the first place, we have the impression that most orchid-experts and lovers are more inclined to visit a well-known location by motor car than that they have the intention to walk along steep mountain paths during long days in remote parts of the area far away from motor roads. Furthermore, one should not overlook the point that a region as the Vercors is of an unendless vastness when one tries to find an orchid of which the biotope requirements are vaguely known. If it is not possible to define the potential locations to a certain extent, the search is like looking for a needle in a haystack. We were increasingly able to precise the potential locations by discussing the characteristics of a growing list of locations where we found the species.
All locations were indicated on a map, the total number of plants was counted, the location of the slope was indicated, and the degree of shadow was determined. Finally, we made a list of all plants growing in a circle with a diameter of two meter around the Orchis spitzelii plants. On some locations attention was given to the composition of the substrate. Sometimes the plants were not growing in clusters, but in a more or less connected area. We considered this always as one location. In all cases where a clear spatial separation between groups of plants could be recognised, we determined this as two locations. The shortest distance between two locations was some hundred meters.
The results of the research can be found on the distribution map and in the table.
The table is available in Excel-format and can be downloaded here.
Discussion of Results found in Publications
In the first place, we want to pay attention to the information regarding Orchis spitzelii locations as this has been published previously. We can discuss this information, using the data of our investigations. In Section 3.1 we will pay further attention to the characteristics of the locations in the Vercors.
The information on Orchis spitzelii as has been published previously, is sparse and often based on only a few observations. The low number of locations known until recently causes this.
* Mrkvicka (1992) discusses the well-known locations in the Austrian Alps. Orchis spitzelii is found there on steep slopes with bluegrassland, which are apparently quite similar with the locations 24, 31, 32 and 33 in the Vercors. Mrkvicka�s views are discussed in more detail in the next section, as they can inspire us on the interpretation of the distribution of Orchis spitzelii in the Vercors, which is at stake in that section.
* Delforge states that Orchis spitzelli is generally growing at locations where snowfall in winter is high, and where the snow layer will not melt away easily. Probably, this is based on an observation in Autrans in the northern part of the Vercors. He observed there in 1981, when he visited the location for the second time, that the location was still snow-covered in the beginning of June. In the first place, attention has to be given to the fact that in the Vercors snowfall in late winter and spring and the accompanying snowcover can differ substantially from year to year. During his second visit Delforge was confronted with a situation in which extremely much snow was fallen in the previous period. Additionally, the difference in climate between Autrans and the locations in the south-eastern part of the Vercors is very significant, which implies that snow in Autrans will melt away two till three weeks later in the season than in the south-eastern Vercors.