Authors:G. Kemény, K. Penksza, Nagy Z., and et al.
A neighbourding -quadrate transect study was conducted in order to examine the possibile relationship between small scale topography and coenotaxa occurrence and cover in subassociations of Festucetum vaginataeRapaics ex Soó 1929 sandy grassland plant community near Fülöpháza. These investigations served as a starting point in later soil seed bank studies. Cover of species was recorded in three transects of different exposition starting on the top of different dunes and ending in the depressions. Subassociations and facies forming species of the community occurred in all investigated transects. Parts of the transects could not have been classified unambiguously into any of the coenotaxa mentioned in the literature. In these zones the charactersitic species of the different subbasociations and facies were occurding together. These patches are propbably also the ones where changes in dominance relations and simultaneous spread of a species can relatively easily happen, as it is the case with Cleistogenes serotina. Annual vegetation of the open sandy grassland, ond the other hand, has occured only in the transition zones, between the subassociations or facies. In these transects moss-lichen synusia were peresent usually in the subassociation Festucetum vaginatae pennatae Kerner 1863.
The spores of 6 species of arbuscular mycorrhizal (AM)
fungi (Glomeromycota) were collected, described and illustrated in three
different habitats of semiarid open sandy grasslands in Hungary (Nagykáta,
Domonyvölgy, Fülöpháza). Glomus constrictum, G. corymbiforme, G. microcarpum,
Sclerocystis sinuosa, Scutellospora dipurpurescens, and S. persica are reported
firstly from Hungary.
The survey was carried out on the seed bank of several patches of an open, semiarid sandy grassland (Festucetum vaginatae Rapaics ex Soó 1929 (Borhidi 1996)). We chose four, approximately 20 m × 20 m large, adjacent patches, different in their species composition and total cover. Soil samples were taken in early spring and at the end of summer, in two consecutive years. We determined the seed bank of the samples with the seedling emergence method. The fact that we found the seeds of only two species that were not present in the vegetation indicates the isolated and without artificial disturbed state of the grassland. The vegetation and the seed bank of the patches showed a low degree of similarity in the same period, while the composition of the spring aspect reflected clearly in the seed bank of late summer in all four patches. Results showed that mosaic-like appearance is not only characteristic of the vegetation, but also the seed bank of the soil. Differentiation of the seed bank manifested mostly after the period of seed-fall, at the end of summer, while in early spring it was less expressed. On the basis of the differentiation of the seed bank we can conclude that not the dispersion of seeds, but natural vicinity of mother plants was decisive in forming the spatial variation of the seed bank.
Research on wild bees (Apiformes) was conducted in the Lower Oder Valley (NW Poland) at Natura 2000 sites near the border between Poland and Germany. The analysis involved 3 landscape types with xerothermic and sandy grasslands, differing in the proportion of woody vegetation. In total, we collected there 4158 specimens of Apiformes, representing 180 species. We have proved that mid-forest grasslands with a high proportion of thermophilous broad-leaved forests and xerothermic shrub communities are equally attractive to wild bees as open habitats (sandy grasslands, xerothermic grasslands/heaths). We observed varied responses of wild bee species with specific functional characteristics to increasing proportion of woody vegetation. The grasslands surrounded by forests were characterized by the highest number of cleptoparasitic species. In contrast, solitary and social bee species preferred forest-steppe habitats. However, in open habitats, solitary bees were the most abundant. Moreover, open habitats were distinguished by the highest number and abundance of rare species. Active protection of thermophilous grasslands is crucial for biodiversity conservation, also with respect to the natural resources of Apiformes. Preservation of biodiversity in threatened xerothermic and sandy grasslands should be one of the key objectives of nature conservation in European countries. Currently, more and more actions are undertaken to improve their condition and to restore those particularly valuable and threatened habitat types.
operation of violaxanthin cycle and the PSII quantum yield in sandygrassland species.
Plant Physiol. Biochem.
(Special issue) 327.
Mile, O., I. Mészáros, Gy. Lakatos and Sz. Veres. 1999. Spatial changes in
Authors:K. Pintér, Z. Barcza, J. Balogh, Sz. Czóbel, Zs. Csintalan, Z. Tuba, and Z. Nagy
Interannual variation of carbon fluxes of grasslands on sandy (5 years data) and heavy clay soils (4 years data) have been analysed. The sandy grassland was carbon sink in 3 (2004, 2005, 2006) out of the investigated 5 years. Its annual C-balance is precipitation limited, the relation seems strongly conservative, with r
of 0.83. More than half of the net source activity fell to the summer droughts. The heavy clay grassland was net source of carbon in one year (2007) only with no whole year record from 2003, a drought and heat wave year. Dependence of the C-balance on precipitation was somewhat weaker (r
=0.57) than in the sandy grassland. Length of growing period showed less variation here compared to the sandy grassland. Recovery of sink activity after rains was much slower for the heavy clay grassland than for the sandy grassland. The reason behind is that the amount of water required to reach optimal soil water content for plant functioning is several times larger for the mountain grassland. This fact and the low conductivity of the clay soil for water decrease the heavy clay grassland’s recovery potential after droughts. Owing to these soil characteristics, the clay grassland may be more vulnerable to droughts in terms of decreased C-assimilation and (soil) carbon losses under the predicted drier summers even if the annual precipitation sum was higher by 10.7% on average for the mountain compared to the sandy grassland. The annual precipitation sum is close to the threshold, below which the grasslands may turn into source of carbon. While in one hand this can be viewed as an example of ecosystem scale adaptation to available water, drought events also involve loss of soil carbon and a potential positive feedback between source activity and decreasing net primary production, on the other.