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.

摘要

过度放牧给全球牧场生态系统和人类生计造成严重问题。带有固定围栏的牧羊场在欧洲越来越普遍。然而，很少讨论它们对生物多样性的影响。我们的目的是测量匈牙利中部一个实验羊场中草地植被的退化情况，并评估排除放牧后碱性草地的恢复情况。在草地恢复的前三年，我们将严重过度放牧的地块的植被与排除过度放牧的地块的植被进行了比较，这些地块用三种剂量的粪肥（0、20 和 40 吨/公顷）处理。第三年，过度放牧地块以需要养分的粗野植物物种为主，目标草地物种的覆盖率仅为19.8%。放牧排除后，Festuca pseudovina在被排除的地块（51.1%）中比在过度放牧的地块（8.9%）中更丰富。在实验结束时，围栏的退化率（0.2 对 3.7）和营养物的覆盖加权生态指标值（3.8 对 5.1）显着低于过度放牧地块。施肥对草地恢复无显着影响；因此，在研究的生态系统中没有必要。我们建议避免在有固定围栏的牧场放牧，尤其是在拥有高保护价值栖息地的地区。除了导致草原退化外，放牧围场还充当景观疤痕和可能对周围景观产生负面影响的问题物种的繁殖源。