Coenological and synphysiological investigations on loess grassland vegetation (Salvio-Festucetum rupicolae) close to Gödöllo Hills (Hungary)

Abstract

Parallel coenological and synphysiological examinations were carried out on three typical xerophilous loess grassland stands of Salvio-Festucetum rupicolae community in the Gödöllõ Hills, near Isaszeg village. Three stand types, a Carex humilis , a Chamaecytisus austriacus and a Stipa dasiphylla dominated ones were investigated at the same spatial scale (mesoscale). In our sample area apparent dominance by three species ( Festuca rupicola, Stipa dasiphylla, and Carex humilis ) suggested that these stands of this subassociation have been emerged from three types of differing species composition. According to these analyses three groups dominated by Carex humilis, Chamaecytisus austriacus and Stipa dasiphylla of festucetosum rupicolae subassociation of a stand of Salvio-Festucetum rupicolae association were separated. Results of the synphysiological measurements show, that water shortage and senescence in autumn are responsible for the different physiological performances of the three types. In the well-watered summer period we found significant difference only between the physiological activity of the Carex - and Chamaecytisus - dominated types, however this difference is due to the significant LAI-difference and after relating photosynthesis to 1 m ² leaf area, the difference is non-significant.

Keywords

coefficient of variation, coenology, grassland, loess stands, multivariate analysis, Salvio-Festucetum rupicolae Zólyomi 1958, synphysiology

Seasonal and daily pattern, temporal and spatial variability of ecosystem CO ₂ -exchange in a temperate Pannonian loess grassland

Abstract

In the photosynthetically most active spring, summer and autumn vegetation period the investigated grassland did maintain a relatively strong daytime carbon gain. During winter the grassland displayed a slight daytime carbon loss. These data suggest that the grassland was a weak sink for carbon in the investigated period. CO ₂ -exchange variability during the day seemed to be independent from that of the daily photosynthetic radiation. Thus other factors like soil respiration, soil moisture content and temperature and their interactions could be responsible for the high daily variability of grassland CO ₂ -exchange. The considerable temporal (daily and seasonal) variability of the grassland CO ₂ -exchange can be considered as a characteristic feature of the grassland CO ₂ -exchange. In the investigated loess grassland vegetation the variability of CO ₂ -exchange showed clear dependence on measuring area, which is obvious in the CV of NEE. We hypothetised that the spatial scale with the lowest variability is the characteristic area of the grassland ecosystem’s CO ₂ -exchange (CO ₂ -exchange physiological unit). In general decreased variability indicates a more regulated state.

Keywords

carbon-balance, temperate grassland, chamber technique, net ecosystem CO ₂ -exchange, carbon gain

Pollution of garden soils and vegetables in the Šalek valley

Abstract

Soil pollution and accumulation of heavy metals in the most common vegetables were investigated in the Šalek Valley, where the largest Slovenian thermal power plant of Šoštanj (ŠTPP) is located. Methods were chosen according to international and Slovenian standards. Heavy metal content in soils and plants was determined by ICP-MS, ETAAS and hydride technique after appropriate digestion of samples. Results revealed that garden soils in the Šalek Valley are not polluted in general with heavy metals. On the contrary, some plant species exceeded permitted levels of Cd. Our results showed that the most sensitive group of plants are still affected, although emissions of heavy metals markedly decreased after the desulfurisation device was built at the ŠTPP.

Keywords

Vegetables, Pollution, Heavy metal accumulation, Cadmium, Lead, Mercury, Arsenic

Harmful impact of exceptional cold air outbreak in april 1997 on silver fir in Croatia

Abstract

After a severe outbreak of cold air in mid and late April in 1997, locally occurring damages on twigs and needles of silver fir were recorded in some forests in Croatia. Field examinations in the first half of July 1997 revealed the damages on one-year and older needles while fully developed twigs of current year growth were left intact. Southern and western slopes with fir growing forests represented typically affected sites. Further laboratory analyses confirmed the field observation that no harmful insect or pathogens were the cause of these damages. Spread of symptoms, expressed more heavily at lower elevations, indicated a probable connection with recent exceptionally cold air outbreak in mid-April. Physiological disturbances caused by potassium deficiency are discussed in the light of specific occurrences of damage symptoms on silver fir trees.

Keywords

Abies alba , cold air damages, potassium

Algae of specific environments in Slovenia

Abstract

Algae studies were carried out in some specific biotopes of Slovenia: eutrophic lakes (Koseški bajer, Sotelsko jezero), peat bogs (Lovrenška jezera, Šijec), waterfalls (Savica, Krka falls, small waterfall on Pohorje), springs (springs at Medvedje Brdo and Pohorje, hot spring at Terme Čatež, mineral spring at Rimski vrelec), brackish waters (Fiesa lake, Dragonja estuary), hypereutrophic biotopes (manure water, constructed wetlands), aerial biotopes (concrete wall, stony wall, lime tree trunk ( Tilia platyphyllos ), limestone rock, Krška jama cave) and the Dragonja River.

Samples were taken seasonally at 26 sampling sites in 1998, 1999, 2000 and 2001. Similarity in species structure and abundance of algae were determined with the Bray-Curtis coefficient of similarity.

Altogether, 537 species and subspecies of algae (of nine classes) were determined and most of them belonged to Bacillariophyceae. 146 species and subspecies were identified for the first time in Slovenia; of these 107 belonged to Bacillariophyceae, 28 to Cyanophyceae, six to Chlorophyceae, four to Zygnematophyceae and one to Xanthophyceae.

The appearance of almost half of all species and subspecies was limited to a single sampling site. Eight species ( Achnanthes minutissima , Cymbella affinis , Cymbella silesiaca , Gomphonema angustum , Navicula veneta , Navicula sp., Phormidium sp. and Trentepohlia aurea) were present in more than half of all specific biotopes.

Keywords

algae, eutrophic lakes, waterfalls, springs, peat bogs, aerial biotopes, constructed wetlands, caves, brackish waters, manure waters