The Vegetation of Scottish Pine Woodlands and Dutch Artificial Coastal Pine Forests; with some Remarks on the Ecology of Listera Cordata

Coniferous woodland is not indigenous to the semi-humid and subatlantic temperate lowland climatic region of the Netherlands. However, extensive forests of conifers have been planted, mainly since the end of the 18th century. Pinus sylvestris and Picea abies were the main species planted up to the 20th century, but more recently Pseudotsuga menziesii, Larix leptolepis, and to a lesser extent other species have been used. In the coastal dune area, Pinus nigra, both ssp. nigra and ssp. laricio, is the exotic tree that is planted most frequently. From an ecological viewpoint, these forests have not so far been considered as separate plant associations. Since they were mostly lacking in faithful2) species, they have been classified as “cultivated forest communities” under the native deciduous woodland associations, in most cases inside the Querceto-Betuletum (vide e.g. Morzer Bruijns & Westhoff 1951, Westhoff 1954b, 1955, 1957). In the course of the last century, however, some circumborealmontane neophytes have migrated spontaneously into these artificial forests. This has also been observed nearly in Germany (Asgherson & Grabner 1907, Hegi, Schutt 1936 etc.). So far, in the Netherlands Goodyera repens, Linnaea borealis and Lycopodium annotinum were known as such neophytes, though some doubt existed as to whether these species should be considered as “glacial relics”. Goodyera repens, which was not mentioned by Oudemans (1874), was first recorded in the Nctherlands in 1880 in the Leuvenum forest near Hulshorst (Prodromus Florae Batavae ed. altera I, 4, 1916); Linnaea borealis, not yet mentioned in the Prodromus Florae Batavae ed. altera (I, 2, 1903), was recorded first from Appelscha in 1920 and from Floogeveen in 1928 (Beyerinck, 1929b). Beyerinck (l.c.) stated that the latter pine forest dated from 1888 and concluded that Linnaea might have established itself there after 1888. From morphological observations, he estimated the plants to be 26 years old, which means that the species must have been present in 1903, when the pine forest was only 15 years of age. On the other hand Thyen (in Buchenau, 1936, p. 380) observed, that nearby in Germany Linnaea did not occur in woodlands before the pines fruited, the species apparently being introduced by seed devouring birds; Meyer & van Dieken (1947, p. 193) suggest that the trees must be at least 70 years old before Linnaea occurs. At present 12 localities of Linnaea are known in the North Netherlands, viz. 11 in the Drenthian District (Hoogenraad, 1951; Van Ooststroom, 1958, in litt.) and one on the Westfrisian island of Terschelling, where it has been discovered quite recently (1958) in Scotch pine forest (Wilgke, 1958; see § 4 and table 3). Moreover, there is one locality further to the South near Flulshorst in the Guelder District (van Ooststroom, 1958, in litt.). For Goodyera repens, 17 localities are recorded in the “Plantenkaartjes van Nederland” (IV, 1937, p. 214) and are distributed throughout the mainland of the country. In 1955, mr. T. Salverda (Groningen) discovered Goodyera repens for the first time on the Westfrisian islands, viz. on the island of Ameland in an artificial forest of Pinus nigra ssp. nigra. In 1957, the present authors observed the species for the first time on the island of Terschelling in two localities, one in Austrian and the other in Corsican pine forest. In relatively old pineforests on the Dutch mainland, these neophytes are often accompanied by other species which are, in general, characteristic of coniferous forests, but also occur in the Netherlands in old deciduous woodland, e.g. Trientalis europaea, Pyrola rotundifolia, P. minor, Vaccinium myrtillus, V. vitis-idaea. These species, like the neophytes themselves, are considered faithful species of the phytosociological order Vaccinio-Piceetalia and the alliance Vaccinio-Piceion (see e.g. Braun-Blanquet, Sissingh & Vlieger 1939, Oberdorfer 1957). There is some reason, therefore, to consider the artificial pinewoods of the Netherlands and adjacent Germany as a “nascent association” of this alliance, as was suggested for dwarf shrub communities of the same alliance on the Westfrisian islands by Westhoff (1947).