Zs. P. Komáromy szerk.: Studia Botanica Hungarica 14. 1980 (Budapest, 1980)

Szolláth, György: Data to the flora and vegetation of the Gerecse Mountains I.

It must be underlined that Que reus cerrls is Included in every sample taken in hornbeam-oak forests (Q.-Cp.pann. ) - oven if with low AD value (+). This phenomenon correspond with the conclusion of Száraz (1976) that the frequent occurence of Quercus cerris is very striking in the hornbeam-oak forests (Q.-Cp.pann.) in the Gerecse Mts. In his examinations of association analysis he pointed out that the sharp isolation of the stands of the Gerecse Mts. from the same plant community of the Vértes and Visegrádi Mts. is caused just by Quercus cerris

, as locally characteristic of the Gerecse Mts., differential species is the examination. He cannot offer sure resons for this phenomenon since plantation of Quercus cerris is very frequent (i.e. not native) but its energetic renewal after clear-felling is also possible. The most typical species of the stand - besides the mentioned oneB - are Stellaria holostea (+-1 - 1), Mercurialis perennis

(+ - 1), Hedera helix f

+ - l),

Poa nemoralis (1 - 4-5) - forest of dry character (

Melica unlflora

, Majer 1968). Carex pilosa (+ - 1 ) - semi-dry character (Majer 1968), Asperula odorata (+ - l),- Heracleum sphondylium (+) and Cerasus avium (+). Untroubled, typical stands can be found only In few places; plant communities are composed mainly of degraded coppices and oak-ash forests. The single beech stand is to be found in a narrow valley of Nagy-Gete. Its underwood Is scattered, dominant species are Carex pilosa and Poa nemoralis

. Since there were no samples taken here it cannot be decided whether it is a beech consociation of hornbeam-oak forest (Q.-Cp. pann.) or an extrazonal beech forest (

Melitti-Fagetum

). In addition this plant community lives on the northern margin - and the vallies stretching into it - of Magos-hegy as narrow belts. Its degraded condition is evident as Carpinus betulus dominants and it is mixed with old acacia groves in some places. It is also characteristic of its underwood that the still existing Carpinion

, Fagetalia

, etc. elements (

Hedera helix

, Heracleum sphondylium

, Stellaria holostea

. Mercurialis perennis

. Carex pilosa

, Melica uniflora

, My cells muralls

) are seriously driven back by nitrophyl weed communities (Sambucus nigra

, Utrica dioica

, Chaerophyllum temulum

, etc.). Among all, the most degraded stand can be seen in the eastern exposition on the steep slope of Henrik-hegy . Quercetum petraeae-cerris pannonicum (Soó 1964) (=Potentillo albae - Quercetum petraeae-cerris pannonicum - Zólyomi 1958) (On the basis of 3 samples) Old, degraded, high matured Turkey oak forest (Q.p.-c.pann. ) (

Quercus cerris - 5, Quercus petraea - +) is to be found on deeper soils of the north-western part of Liget-hegy. Ligustrum vul gare (1), Acer campestre (+ - D.

Sorbus torminalis (+), Crataegus monogyna (+), C. oxyacantha (+), Cornus mas (+), Euonymus verrucosus (+) and Fraxinus ornus (+) represent the relatively luxuriant shrub layer of this community but it was rather disturbed when ranging this field because of the preceding select-cutting. In spite of this - regarding the presence of revealing species (

Festuca hete rophylla- + - 1, Polygonatum latifolium - +, P. odoratum - +, Pulmonaria mollissima - +, Primula verls - +, Lathyrus niger - +, etc.), definitely a degraded stand of festucetosum heterophyllae (Zólyomi 1958) subassociation is to be found here. Orno - Quercetum pannonicum (Zólyomi 1958, Soó 1964) (On the basis of 5 samples) The Turkey oak - villous oak forest (Orno-Q.pann. ) community covers nearly the biggest area. Its beautiful stands are to be seen in Nagy-Gete and Magos-hegy on poor soils, in southern exposition on almost flat plateaus. Three layer of this community Is represented by Quercus pubescens (2 - 3), Qu. cer ris (+ - 2) and Fraxinus ornus (+ - 3), its rich shrub stratum is composed mainly of Fraxinus ornus (+ - 1), Ligustrum vulgare \+), Cornus mas (+), Sorbus torminalis (+), Berberis vulgaris (+).Extreme habitat conditions of Nagy-Gete promote the oryzopsetosum (Zólyomi 1958) subassociation coming into being. In conformity with these conditions, stands tending towards karst schrub-forest (Cer,-Q.) communities are the most characteristic of this field. Frequently occurring species in its hem layer SS