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Tuesday, 24 June 2014

Supporting grassland biodiversity by traditional Hungarian Grey cattle grazing: The magnitude of weed suppression and biodiversity effects are changing along moisture gradient

Conservation of grassland biodiversity is a vital issue worldwide. Extensively managed pastures are of crucial importance in sustaining biodiversity both at a local- and a landscape-level. Most of Europe's former extensive pastures became either intensively used or abandoned. These led to unfavourable changes in species composition, resulting a  loss of biodiversity and linked ecosystem functions and services like biological control, pollination and seed dispersal. History, culture and tradition also suggest the re-introduction of traditional extensive grazing by local breeds. Traditional low-intensity grazing is important in (i) sustaining biodiversity, (ii) in the facilitation of the immigration and establishment of target species and (iii) in the suppression of noxious species. Less attention was given to the suppression of noxious species compared to the first two issues. Cattle grazing is especially suitable for sustaining grassland biodiversity, because of its lower selectivity compared to sheep or horse grazing. However, the effects of cattle grazing strongly depend on the cattle breed, and the duration and intensity of grazing. 
Fig. 1. Traditional Hungarian Grey cattle grazing in the Hortobágy Puszta (East-Hungary, photo by Balázs Deák).

To mimic natural grazing regimes of grasslands traditional cattle grazing with robust breeds (e.g. Heck cattle or Hungarian Grey cattle) in low stocking rates are considered to be proper.. Thus, this kind of management is increasingly introduced in nature conservation and restoration practice in many parts of Europe.

In our paper we evaluated the effectiveness of traditional Hungarian Grey cattle grazing in suppressing noxious species in three grassland types of a mosaic alkali landscape. We tested the following questions: (i) How does cattle grazing affect species composition and diversity of the three grassland types? (ii) What are the effects of grazing on short-lived and perennial noxious species? (iii) Are there distinct effects of grazing for dry-, mesophilous- and wet grassland types?

Our results demonstrated that grazing by Hungarian Grey cattle strongly affected the species richness and composition even in the short run. We also detected a remarkable effect on the specific heights: in all studied grassland types the cover-weighted specific heights were significantly lower in grazed plots. This was due to grazing benefitted creeping and rosette-forming species like Plantago lanceolata, P. major, P. media, Taraxacum officinale, Trifolium repens and Polygonum aviculare.

Our results suggest that the traditional grazing by Hungarian Grey cattle have beneficial effects already in the short run by the suppression of noxious species in all studied grassland types. The increase in biodiversity in mesophilous and wet grasslands was likely caused by the high rate of suppression of tall-growing noxious competitor species Elymus repens and Phragmites communis.

We found that the effect of grazing was quite different in grassland types along the dry-mesophilous-wet gradient with the same stocking rates (1 cattle/ha). It was the most expressed in the wet grassland type, although yearly fluctuations were also the highest here. Moderate yearly fluctuations were detected in the dry grassland, but compositional changes were more directed and not likely influenced by year-to-year differences (i.e. by precipitation differences). The effects were intermediate in the mesophilous grasslands between the two other grassland types. We can conclude that extensive Hungarian Grey cattle grazing is effective even in the short run to suppress noxious species and to create a mosaic vegetation structure of short- and tall species, which enables to maintain high species richness in the landscape. In addition, Hungarian Grey cattle can feed in open habitats along a moisture gradient from dry grasslands to wet habitats including also alkali marshes. Thus, in highly mosaic landscapes it is better suited for grazing management than other non-traditional livestock types, which need a more homogeneous vegetation structure.

For more detailed information read our open access paper entitled ‘Traditional cattle grazing in a mosaic alkali landscape: Effects on grassland biodiversity along a moisture gradient’ published in PLOS One which you can freely download here. 

Contact addresses 

Péter TÖRÖK, Orsolya VALKÓ, Balázs DEÁK, András KELEMEN, Béla TÓTHMÉRÉSZ

MTA-DE Biodiversity and Ecosystem Services Research Group

E-mail addresses:
molinia@gmail.com (PT)
valkoorsi@gmail.com (OV)
debalazs@gmail.com (BD)
kelemen.andras12@gmail.com (AK)
tothmerb@gmail.com (BT)

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