Kelemen et al. (2014) Biodiversity and Conservation

András Kelemen, Péter Török, Orsolya Valkó, Balázs Deák, Tamás Miglécz, Katalin Tóth, Tamás Ölvedi & Béla Tóthmérész (2014): Sustaining recovered grasslands is not likely without proper management: vegetation changes after cessation of mowing. Biodiversity and Conservation, in press. DOI: 10.1007/s10531-014-0631-8


Abstract
Grasslands recovered by sowing low diversity seed mixtures of local provenance are usually managed by mowing. Besides restoration success only a few studies have focused on the direct effects of post-restoration mowing on recovered grassland vegetation. In this study we followed vegetation changes in 13 successfully recovered grasslands in 5 × 5-m-sized sites with continuous and ceased mowing at Hortobágy National Park, East-Hungary. We asked the following questions: (i) What are the effects of cessation of mowing on the vegetation structure and diversity of recovered grasslands? (ii) What are the effects of cessation of mowing on the abundance of sown grasses, target and undesirable species? (iii) Is yearly mowing an appropriate management tool for the maintenance of recovered grasslands? Our results showed that the cessation of mowing caused litter accumulation, while diversity, total vegetation cover and the cover of sown grasses decreased compared to the mown sites. The cover of undesirable perennial species was significantly higher in unmown sites than in mown ones. The species composition of mown sites remained more similar to near-natural grasslands than the unmown ones. Our results suggest that without regular post-restoration mowing the favourable status of recovered grasslands can rapidly decline due to litter accumulation and by the expansion of undesirable species, even in the short-run. We also stress that while yearly mowing is enough to maintain grasslands recovered by low-diversity seed sowing, it cannot be considered to be enough to recover target vegetation composition.


Keywords
Grassland restoration, Seed sowing, Abandonment, Post-restoration management, Biodiversity, Cirsium arvense

Török et al. (2012) Journal for Nature Conservation

Péter Török, Tamás Miglécz, Orsolya Valkó, András Kelemen, Balázs Deák, Szabolcs Lengyel, Béla Tóthmérész (2012): Recovery of native grass biodiversity by sowing on former croplands: Is weed suppression a feasible goal for grassland restoration? Journal for Nature Conservation 20(1): 41-48.


Abstract
Grassland restoration on former croplands offers good opportunity to mitigate the loss of grassland biodiversity. Weed suppression can be another benefit, which becomes increasingly important because of the high recent rate of abandonment of arable lands in Central and Eastern Europe. Our aim was to evaluate the usefulness of sowing two low-diversity seed mixtures followed by annual mowing, a frequently used restoration technique, in weed suppression. We found that rapidly forming cover of sown grasses effectively suppressed short-lived weeds and their germination except in the first year. The detected dense seed bank of short-lived weeds points out the possibility and threat of later weed infestation. In the short run perennial weeds cannot be suppressed easily by sowing and annual mowing. We found that the effectiveness of seed sowing followed by mowing in weed suppression can be different on sites with different history or seed mixture. Rapidly establishing perennial weeds, such as Agropyron species were only detected in former alfalfa fields; Cirsium arvense was found in former cereal and sunflower fields but not in former alfalfa fields. We found that the rate of weed suppression and success was influenced by the seed mixtures used. In several alkali restorations the high proportion of perennial weeds was detected in year 3. In loess restorations, much lower scores were typical. This was likely caused by the different seed mixture used. The loess seed mixture contained seeds of a clonally spreading tall-grass, Bromus inermis, which could compete more effectively with clonally spreading weeds, than could short grass species with or without tussock forming. Our findings indicate that post-restoration management require carefully designed actions that are fine-tuned addressing specific threats at the site level.

Keywords
Seed sowing; Weed suppression; Plant trait; Succession; Establishment success; Cropland