Zs. K. Komáromy szerk.: Studia Botanica Hungarica 17. 1984 (Budapest, 1984)
Siklósi, Engelbert: The flora of the pits in the Nature Preservation Area of Ócsa
Valley Main ChaneL These channels should be completed so that the water level could be regulated for the continuance of the valuable bogs (BUZETZKY & ZSUFFA 1979). General botanical description According to the description of A'. BOROS (1936), who was the first notable scientist to study the area, the bogs of Ocsa are inaccessible. Only after the reclamation did it become possible to reach the whole area in 1928. At this time the vegetation of the bog made it possible to investigate the area. This condition rapidly declined because of interference. Now the original vegetation may be found only in small spots. Some of the rare and characteristic species have completely disappeared or are found only in small spots and in few number. The reeds of original lake surfaces, ancient currents can be found only in small areas. In these waters lives Hottonia palustris forming thickets of reed-grass. We could find two glacial relict species in these reeds, i.e. Ur tica kioviensis and Sparganium minimum . Now the larger part of water-surface s are lakes artificially constructed by turf-mining. Reed-grass and coastal vegetation of these lakes are poor in species. The object of this paper is to examine these zones. Rush-beds (Caricetum elatae) succeed the reeds after accretion of the coast. These are the characteristic elements of the swampy area. These associations are composed of Carex elata , Carex riparia , Carex acutiformis and sometimes mixing with Glyceria maxima . The Carici-Menyanthemum is found in the fen windows in which we only rarely find Menyanthes trifoliata . The rushbeds gradually decrease in the dry areas and Carex species construct stands of thick, closed-formation associations. The characteritic species in these are, e.g.: Symphytum officinale , Valeriana officinale , Galium palustre . Some typical associations of the boggy meadows could be recognized. E.g. a) The most characteristic association is the Schoenetum nigricantis which to a large measure has become the victim of turf-mining. The organic matter accumulation is highest in this area. In this association may be found Cladium mariscus. b) The dominant association in the wet area is Juncetum subnodolosi. In these places some times large numbers of Eriophorum latifolium occur. c) On the vast meadow the Molinietum coeruleae association is the most frequent. In some places bushes of Salix cinerea add variety to the meadows. The spreading of Salix is hindered by frequent lumbering. These areas are rich in species. Koeleria jávorkeae is a characteristic endemic species of the area. Glacial relicts are e.g.: Adenophora liliifolia , Orchis incarnata , Orchis laxiflora, Anacamptis pyramidalis, Dianthus superbus, Iris sibirica. Also characteristic are Gentiana pneumonanthe , Sanquvisorba officinalis , Lychnis flos-cuculi , Veratrum album . d) In some small areas the appearance of Festuca pseudovina and Plantago maxima mark increasing salinity, which is a consequence of the extensive drainage and the drying of the soil. The forests are the most complex associations of the area. Fraxino pannonicae - alnetum is the most characteristic association. The trunks have proproots ( Alnus glutinöse ) and Thelypteris palustris flower on them. In some places in large numbers occur Hottonia palustris . Of all remaining isolated forests of Ocsa this alder forest is the most endangered one, it is almost completely dried up. Probably the deepening of a near by gravel pit caused the drop of subsoil watertable. In higher places gallery forest (Fraxino pannonicae - Ulmetum) occurs. The indigenous species were mainly Quercus , Ulmus , Fraxinus but now as a result of planting there are Populus and Robinia as well (A level). The shrub stratum is rich in species (B level): Sambucus nigra, Frangula alnus , Viburnum opulus . The characteristic species in the herb layer are e.g. Convallaria majális , Polygonatum latifolium, Orchis militaris. The montane species indicate relationship with mountains of medium altitude. The mentioned vegetation types that are gradually disappearing were once integral part of the landscape of the Great Hungarian Plain. The original vegetation can now be studied in small patches of the protected area. Survival of these spots and the maintanance of steady conditions are very difficult to ensure because of effects the surrounding agricultural co-operatives. The inconsiderate reclamations, the use of artifical fertilizers and plant protectives of a countless quantity have frequently unfavourable influences over the natural associations living in only small patches, since those are easily affected because of their limited size and their constancy may easy be overbalanced .
