Vegetatiekundig en oecologisch-geografisch onderzoek van het Quercion robori-petraeae in de Nederlandse zandgebieden ten Zuiden van de Waal

In this thesis are given the results of an investigation of the vegetation, habitat and distribution of the Quercion robori petraeae (oak-birch-woods) in the sandy regions of N-Brabant and Limburg and in the ,Rijk van Nijmegen'. Data obtained from literature and from investigations by the author made in other parts of the Netherlands are compiled.The investigated area, where the Quercion robori-petraeae must have dominated in the original landscape, covers:
1. North Brabant, except the holocene alluvia in the north western part and along the river Meuse;
2. North and Central Limburg, except the valley of the river Meuse (its southern limit is roughly formed by the line connecting Echt and Koningsbosch);
3. ,Rijk van Nijmegen', which comprises the municipalities of Nijmegen, Ubbergen, Groesbeek, Heumen, Overasselt and Wychen);
4. The borderland east of Brunssum and Schinveld.To describe the Quercion robori-petraeae use has been made of ,sociological groups of species', viz. groups of species, which show a strong similarity in sociological amplitude.In chapter two the natural condition in the investigated area is described. The climate is compared to that of the Netherlands: it is relatively warm in summer, with a gradual increase in temperature going eastwards, and relatively mild in winter with a gradual increase in temperature going westwards, while the mean annual precipitation is relatively slight, with decreasing yearly totals going eastwards (par. 2.1). The landscape, except for some peat bogs, is built up of cover sands, low terrace, push morraine, loess, blown sands derived from pleistocene riverterraces or cover sands, old pleistocene terraces and tertiary sands. Short descriptions of distribution, age, origin, topography, texture and the main soil types are given (par. 2.2).In chapter three a general historical survey of the deciduous forests in the investigated area from the Neolithicum onwards are given. In this period deforestation began. Up to about 700 AD this process in general probably took place very gradually, but from 700-1200 AD the wooded areas were greatly reduced, corresponding with the formation of many settlements. By the late middle ages the landscape had mostly turned into vast stretches of heather, on many places alternated with sand drifts, and so it remained until far into the nineteenth century. Reforestation then started, first mostly with oak coppices, later, in the twentieth century, mostly with conifers. Much of the heaths were reclaimed and also small remnants of the original forests which mostly grew in moist to wet places in the low sandy areas, which are crossed by many brooklets. Thus the present day culture-landscape was formed. Of some of the still existing forests very old data were collected, viz. on those of the push moraine in the ,Rijk van Nijmegen' (the oldest record dates back to Roman times), the ,Echterbosch' (the oldest record is from the early middle ages), the ,Liesbosch', the ,Ulvenhoutsche Bosch' and the ,Mastbosch' (which were recorded for the first time in the late middle ages).Chapter four deals with the classification of the Quercion robori-petreaea of the Netherlands. The chief criterium used was the floristical composition - as done is by the French-Swiss school, but the accent is placed rather on ,sociological groups of species' than on fidelity' (par. 4. 1). In par. 4.2 a survey is given of the sociological groups in which all the species in the described oak-birchwoods are arranged. To every group the sociological amplitude, the amplitude in connection with the chemical composition of the soil and with the hydrology (the most important environmental factors) and the dynamic indication are added. In par. 4.3 a historical survey of the classification of the Quercion robori-petraeae in the Netherlands is given and discussed. The following new classification is proposed:Alliance Quercion robori-petraeae
   (Sub-alliance Violo-Quercion)
      Association Maianthemo-Quercetum ass. nov.
         Sub-association Maianthemo-Quercetum anemonetosum subass. nov.
            Variant with Athyrium filix-femina var. nov.
               Soil: relatively very rich; (moist to) wet
            Typical variant var. nov.
               Soil: relatively very rich; retaining moisture to moist
            Variant with Convallaria majalis var. nov.
               Soil: (moderately rich to) relatively rich; dry to moisture-retaining (sometimes somewhat moist)
         Sub-association Maianthemo-Quercetum typicum subass. nov.
            Variant with Blechnum spicant var. nov.
               Soil: moderately rich (to relatively rich); (moist to) wet
            Variant with Molinia caerulea var. nov.
               Soil: poor (to moderately rich); moist (to wet)
            Variant with Polypodium vulgare var. nov.
               Soil: poor to moderately rich; dry to moisture-retaining (sometimes somewhat moist)
   (Sub-alliance Vaccinio-Quercion)
      Association Querceto-Betuletum TÜXEN 1930 em. DOING 1962
            Variant with Molinia caerulea var. nov.
               Soil: poor; moist to wet
            Variant with Festuca tenuifolia var. nov.
               Soil: poor; dry to moisture-retaining (sometimes somewhat moist)In chapter five the distribution of the Maianthemo-Quercetum and the Querceto- Betuletum outside the Netherlands is given. Both associations occur chiefly in the Northern Atlantic of Europe.In chapter six the Quercion robori-petraeae of the Netherlands is described. In par. 6.1 the vegetation-analysis is explained. The (abundance-)dominance of the author's records from the investigated area is determined with the aid of the scale Of SEGAL and BARKMAN (pg. 0 W ); for all the other records the traditional BRAUN-BLANQUET scale in six parts was used.In the eight tables in which the floristical diversion of the variants is rendered (appendages 1-8) the species are placed in sociological groups (for the composition and sequence of these groups cf. par. 4.2) and the records according to their geographical origin, for which the following regions are distinguished (mostly plant-geographical districts or subdistricts; cf. par. 6.2):Campine district (Ke)
Low terraces of North and Central Limburg, North-east Brabant and the ,Rijk van Nijmegen' and also the Pliocene border country east of Brunssum and Schinveld (S1)
Push moraine of the,Rijk van Nijmegen'(S2)
Veluwezoom from Doorwerth to Dieren (S3)
Eastern part of the Achterhoek (S4)
South-eastTwente (S5)
South Limburg (ZL)
Valley of the IJssel (G1)
Veluwe, Utrechtse Heuvelrug and the Gooi (G2)
Guelders Valley (G3)
Drenthian district (Dr)
Coastal area (K).In par. 6.3 particulars on the flora of the Quercion robori-petraeae in the investigated area are given.In par. 6.4 the different variants are described in detail. These descriptions refer to the occurrence in the investigated area in the first part and in other parts of the Netherlands in the second part.The first part deals with:
a. Data from the vegetation-records (date and number of each record; name of the woodland and of the municipality, coordinates on the topographical map; topography; geological formation and soil type; history of the wood and the surrounding landscape).
b. Floristical survey.
c. Habitat and distribution.The second part deals with:
a. Data from the records of the vegetation (less systematical and detailed than those of the investigated area).
b. Distribution and geographical differentiation.In Par. 6.5 the described oak-birch-woods in the Netherlands are subjected to a closer scruting: their geographical variation is described by means of local vicariants, which are based on specific combinations of geographically differential species, or occasionnally on one such a differential species. In conclusion a survey is given of the oak-birch woods in the investigated area, which are quite possibly remnants of original forests.