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• Kaszálás felhagyás hatása helyreállított szikes és löszgyepek vegetációjára

  21-29

  Views:

  67

  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. 

• Felhagyott jószágállások növényzetének vizsgálata a Hortobágyi Nemzeti Parkban

  21-27

  Views:

  43

  Extensive grazing, especially sheep grazing is the most important land use type in alkali grasslands of the Hortobágy National Park. Extensive grazing systems rely on some basic infrastructure, such as sheep corrals, wells and stables. Sheep corrals are characterised by intensive land use: grazing, trampling and manuring is concentrated in these places, thus the vegetation of actively used corrals is markedly different from the vegetation of extensively grazed grasslands. I studied the vegetation composition of eight-year-old and sixty-year-old abandoned sheep corrals and extensively grazed pastures in Hortobágy National Park. I recorded the percentage cover of vascular plants in twenty 2×2-m plots. The cluster analysis showed that the vegetation of abandoned sheep corrals was different from pastures. I found that the cover of annual and biennial species was higher, while the cover of perennials was lower in abandoned sheep corrals compared to the pastures. Due to the intensive land use in the past, the proportion of nitrophilous species was higher in sheep corrals, than in the pastures. The cover of competitors was lower, while the cover of disturbance tolerants, weeds and ruderal competitors was higher in sheep corrals than in the pastures. The results suggest that even grassland regeneration started in the sheep corrals and several target species established in the vegetation, the recovery of grasslands similar to extensively grazed pastures takes longer time. 

• Overutilization of Pastures by Livestock

  29-35

  Levente Czegledi

  Andrea Radacsi

  Views:

  263

  Soil degradation caused by overgrazing is a worldwide problem. The degradation of an overutilized area occurs mainly where animals prefer to spend extra time because of the attractants that are around gateways, water sources, along fences or farm buildings. High grazing pressure decreases plant density which results in changes of the botanical composition of a pasture. The effect that grazing has on a plant depends on the timing, frequency and intensity of grazing and its opportunity to regrow. Overgrazing adversely effects soil properties, which results in reduced infiltration, accelerated runoff and soil erosion. Evidence has been corroborated with high bulk density values, high dry mechanical resistance and low structural stability. The degradation of the landscape may be a short-term phenomenon and recovery is possible after grazing pressures have been greatly reduced. Management practices have been used successfully to improve grazing distribution. These practices include water development, placement of salt and supplements, fertilizer application, fencing, burning, and the planting of special forages which can be used to enhance grazing by livestock in underutilized areas.
  The authors carried out their grazing experiment on the Hortobágy. The effects of overutilization by livestock on soil properties and vegetation on certain areas of grassland are presented in this paper.

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

  57-61

  Views:

  32

  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.