L. Hably szerk.: Studia Botanica Hungarica 19. 1986 (Budapest, 1986)

Csontos, Péter: Phytosociological description of a hilly country stand of Impatiens parviflora DC

RESULTS The habitat is on a steep (3ü°-60°} slope with N-NE expositions. The parent rock is neutral Miocene andesitic tuff. Dark-coloured forest soil (between Erubaz and Ranker) is characteristic there. The soil is rich in nutrients, it is well aerated and has a quite uniform water supply except for a narrow zone of about 20 m wide along the ridge which becomes a bit drier in summer. This upper zone (zone 1) is covered by the mixed canopy of Quercus petraea

, So

rhus tormina lis

, Carpinus betulus

, Acer campestre, Cornus mas, and Fraxinus ornus

. There is a well-developed shrub layer consisting mainly of Cornus mas

. Corydalis solida and cava, Primula veris

. and Veronica hederifolia are dominant in its spring aspect. Below this strip (zone 2) there is a Mercuriali-Tilietum covering the rocky sites and Querco petraeae-Carpinetum pannonicum growing on the other sites without rocks. These patches are too small for these different forest types to reach typical forms, so the greatest part of this area is the ecotone of the two abovementioned associations. The shrub layer is weak or absent in this area Corydalis cava and solida are dominant in its spring aspect. Impatiens parvifiora is abundant in both zones (with 70-100% cover value), however in zone 2 probably because of the more humid soil it shows greater vitality and productivity. Seedlings of Impatiens appear in the first week of April during the flowering of geophytes. By the time Coryda lis species disappear - the first week of May - Impatiens colonizes the habitat producing already the same cover value as it has in summer. It is possible, because though individuals are small with some leaves only, they are numeruos (700-1400 individual/sq.m.). Peterson mentions a same aspectual changing in the case of geophytes and Impatiens pallida (

PETERSON GRAY 1982). After col nization the I. parvifiora retains its dominance until fall (first weeks of September). The summer aspect of this area in the natural case (without Impatiens

) is subnudum. It consists of some scattered perennials, mainly dicotyledonous species, and the seedlings of Fraxinus excelsior

, but their cover value all together does not reach 10%. So the reason for the success of 1. parvifiora in colonization is that the natural species of the herb-layer leave a suitable and large enough habitat unoccupied and Impatiens is just able to fill it in time and space. Table. Pooled table of the Impatiens parvifiora stand at the ecotone of Mercuriali-Tilietum and Querco petraeae-Carpinetum pannonicum. Number of samples: 10; size: 100 sq.m. each; altitude above see level: 410-510 m, average 460 m; exposition: N-NE; angle of slope: 30°-60°, average 40°; height of trees: 8-25 m, average 17 m; canopy cover: 35-80%, average 60%; height of shrub layer: 1.5-7 m, average 3 m; cover of shrub layer: 0-5(-45)%; height of herb layer: 0.2-0. 7(-l. 2) m, average 0.4-0.5 m; cover of herb layer: 15-98%, average 65-70%. Species are arranged in groups according their phytosociological role following SOO (1968). The letters in brackets after the names mark the layer of vegetation where the given species were found; a = canopy, b = shrub layer, c = herb layer. Species without any indication were found in the herb layer only. Fagetalia species characteristic A-D Fr. for Acerion pseudoplatani Fraxinus excelsior (a, b,c) +-3 Tilia platyphyllos (a,c) 1-2 Acer pesudoplatanus (a, c) +-1 Cystopteris fragilis +-1 Melandrium sylvestre + Parietaria erecta +-1 Ulmus scabra (a,c) +-1 Fagetalia species characteristic for Carpinion Carpinus betulus (a, b, c) +-4 Cerasus avium (a,c) +-2 IV. II n n i i i Stellaria holostea Tilia cordata Fagetalia species Moehringia trinervia Corydalis cava Galanthus nivalis Corydalis solida Gagea lutea Mercurialis perennis Fagus sylvatica (a, b,c) Stachys sylvatica A-D Fr. +-1 +-3 +-] +-1 + +-2 2-4 +-1 V IV IV in m ni n n