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• Az avar rövid életű keresztesvirágú (Brassicaceae) gyomfajok csírázásra gyakorolt hatása

  3-8

  Views:

  41

  Recruitment by seeds is essential both in vegetation dynamics and in supporting grassland biodiversity. Recruitment by seeds is feasible in suitable microsites from the seed rain and/or by establishment from persistent soil seed banks. Cessation of grassland management by grazing or mowing results in litter accumulation, which leads to the decrease of species richness by the decreased availability of open patches. Low amounts of litter are often beneficial, while high amounts of litter are detrimental for seed germination and seedling establishment of short-lived species. However, the magnitude of these effects on germination and seedling establishment in relation to litter and seed attributes are scarcely studied. This motivated us to design an indoor experiment to explore the effects of litter on seedling establishment. We germinated six short-lived Brassicaceae species (Arabidopsis thaliana, Capsella bursa-pastoris, Descurainia sophia, Erophila verna, Lepidium campestre, and Lepidium perfoliatum) with different seed mass under increasing litter cover. We found that both seed mass and litter had significant effect on germination and establishment of the sown species. Small-seeded species were significantly negatively affected by the 300 g/m2 and/or 600 g/m2 litter layers. No negative litter effect was detected for species with high seed masses (Lepidium spp.). No overall significant positive litter effect was found, although for most of the species; total seedling numbers was not the highest at the “bare soil” pots. Our results suggest that the effects of litter accumulation on the germination and establishment of short-lived species are less feasible in case of large-seeded species than on small-seeded ones.

• Biomassza-fajgazdagság kapcsolatok vizsgálata szikes gyepekben és vizes él
  helyeken

  57-61

  Views:

  35

  For an effective conservation and management in grasslands and wetlands it is essential to understand mechanisms sustaining biodiversity. Understanding biomass-species richness relationships is in the focus of recent scientific interest both from the agricultural and nature conservation point of view. We provided a detailed analysis of the relationship between major biomass components (total aboveground biomass and litter), and species richness along a long productivity gradient in grasslands and wetlands. We studied eight types of alkali and loess grasslands and five types of alkali wetlands in Hortobágy National Park, East-Hungary. We found that the relationship between total biomass and species richness can be described by humped-back curves both in grasslands and wetlands. was valid for the relation of total biomass and species richness. We detected the maximum of species richness at total biomass scores of 750 g/m2 in grasslands and at 2000 g/m2 in wetlands. Our results suggest that litter is one of the major factors controlling species richness in highly productive grasslands and wetlands. 

• Kaszálás felhagyás hatása helyreállított szikes és löszgyepek vegetációjára

  21-29

  Views:

  68

  Grasslands recovered by sowing of low diversity seed mixtures are frequently managed by mowing. However only a few studies focused on the direct effects of post-restoration mowing on recovered grassland vegetation. In this study we followed vegetation changes in 13 recovered grasslands, in 5×5-m-sized exclosures with continuous and ceased mowing in Hortobágy, East-Hungary. We asked the following study questions:

  (i) What are the effects of cessation of mowing on the vegetation structure of recovered grasslands?

  (ii) What are the effects of cessation of mowing on the abundance of sown grasses, target and weed species?

  (iii) Is yearly mowing an appropriate management for the maintenance of recovered grasslands?

  Our results showed that the cessation of mowing caused litter accumulation, decrease in total cover and decrease in the cover of sown grasses compared to the continuously mown exclosures. The cover of perennial weeds was significantly higher in unmown exclosures compared to the mown ones. The species composition in mown exclosures remained more similar to reference grasslands than to the unmown ones. Our results suggest that without a regular post-restoration mowing the favourable stage of recovered grasslands can be rapidly vanished caused by litter accumulation and/or by the expansion of undesirable weedy species. We also stress that yearly mowing is solely enough to maintain grasslands recovered by low-diversity seed sowing, but cannot be considered to be enough to recover target vegetation composition. 

• Long-term mowing on biomass composition in Pannonian dry grasslands in the Western-Cserhát

  35-38

  Judit Hazi

  Views:

  56

  This study is focusing on the vegetation of seminatural dry grasslands. Those loess grasslands are valuable with large biodiversity; however their long-term preservation requires regular conservation management. The report demonstrates the results of mowing experiment, designed to suppress the spread of unpalatable grass species, Calamagrostis epigeios. The study site is located in mid-successional loss grasslands, in the Western-Cserhát, near Rád, northern Hungary.

  The study aims to the investigate the followings: Can the unpalatable Calamagrostis epigejos be suppressed by mowing? Are there possibilities to increase the diversity of sward by this? The study aims, to measure potential value-increasing effect of mowing, and to determine the carrying capacity in the aspect of grassland management.

  In 2001, Camagrostis epigeios was the species with the highest coverage rate according to the both treatment types, with an average cover value of 63%. However, as a result of mowing, a significant difference was detected in the amount of litter and legumes species as well. The number of species showed a slight increase in both types of treatment, from 15 to 37 in the mowed plots, but also from 18 to 27 in the control plots. We concluded that mowing twice a year was beneficial to modify botanical composition of a grassland. In a way it was suited well for agricultural usage, in particular grazing which can replace the expensive and time-consuming scythe. It is also a suitable management measure for controlling the native invader species as a Calamagrostis epigeios, and can significantly increase the proportion of species with higher forage values.

  Mowing has significantly increased the density of Calamagrostis epigeios, the species richness, and the diversity in the course of secondary succession. Therefore, mowing twice a year proved to be a successful management measure for controlling Calamagrostis epigeios, and for obtaining a sward composition. The treatment was effective in restoring grassland composition, although the achievement and maintenance of favourable conservation status for the grassland habitat require long-term management planning and regular treatment. According to the objectives, mowing not only promotes the control of the invasive species, but also the economic utilization of the area.

• Recovery of grasslands in former croplands using the combination of seed sowing and hay transfer

  5-11

  Tamas Miglecz

  Views:

  54

  In accordance with general trends in agricultural and natureőconservation practice in Europe, grassland restoration and traditional grassland management has gained increased importance in Hungary. In grassland restoration using of low rates of seed (less than 30kg/ha) and hay cover is suggested. In the present paper the effect of hay cover combined with low rate of seed (25 kg/ha) is studied in early grassland recovery. We aimed at to answer the question whether or not the speed of grassland recovery can be increased with a combined use of seed sowing and hay cover. The establishment of Festuca species was favoured by hay cover combined whit seed sowing. The emergence of shortlived weeds was significantly lower on most of the fields treated with hay cover and seed sowing. The species richness and diversity of early weeds did not differ significantly in fields sown only and fields treated both with seed sowing and hay cover. Our results suggest that the combination of seed sowing and hay cover is successful in fields, where high rate of weed invasion is possible, thus intensive post-restoration management is necessary.