Recovery of extremely overgrazed grassland after grazing exclusion: New paper in Arid Land Research and Management

 Overgrazing causes serious problems in rangeland ecosystems and for human livelihoods worldwide, especially in the arid and semiarid regions. Too intense grazing, trampling and manuring have profound effects on vegetation composition, support the encroachment of weeds and leads to soil erosion. Sheep grazing gardens with fixed fence became increasingly popular and widespread in many parts of Europe, causing a rapid degradation of to the affected vegetation. In our recently published paper, we studied the vegetation of an experimental sheep grazing garden affected by extreme overgrazing (25 sheep per hectare) and evaluated the short-term vegetation recovery after grazing exlusion. The first author of the paper is Krisztina Varga, my former MSc student, who now works at the Karcag Research Institute of the University of Debrecen.

The citation of the paper is the following:

Varga, K., Csízi, I., Monori, I., Valkó, O. (2021): Threats and challenges related to grazing gardens: Recovery of extremely overgrazed grassland after grazing exclusion. Arid Land Research and Management doi: 10.1080/15324982.2020.1869120

Abstract

Overgrazing causes serious problems for rangeland ecosystems and human livelihoods globally. Sheep grazing paddocks with fixed fences have become increasingly widespread in Europe; however, their effects on biodiversity have rarely been discussed. Our aim was to measure the degradation of grassland vegetation in an experimental sheep paddock in Central-Hungary, and evaluate recovery of alkali grasslands after the exclusion of grazing. We compared the vegetation of heavily overgrazed parcels to parcels excluded from overgrazing, treated with three doses of manure (0, 20 and 40t/ha), in the first three years of grassland recovery. The overgrazed parcels were dominated by nutrient-demanding ruderal plant species and the cover of target grassland species was only 19.8% in the third year. After grazing exclusion, the cover of target grassland species increased to 81.0% for Year 3. The dominant grass Festuca pseudovina became more abundant in the excluded parcels (51.1%) than in the overgrazed ones (8.9%). At the end of the experiment, the rate of degradation (0.2 vs. 3.7) and the cover-weighted ecological indicator values for nutrients (3.8 vs. 5.1) were significantly lower in the exclosures than in the overgrazed parcels. Manuring did not have a significant effect on grassland recovery; thus, it is not necessary in the studied ecosystem. We recommend avoiding grazing paddocks with fixed fence especially in areas harboring habitats of high conservation value. Besides resulting in the degradation of grasslands, grazing paddocks also act as landscape scars and propagule sources of problem species that might negatively affect the surrounding landscape.

Sheep grazing in alkali grasslands in the Hortobágy. Photo: Balázs Deák.