Free-range grazing by large herbivores combined with one-time mowing of over-aged heathlands offers an excellent management tool to maintain and enhance biodiversity in degraded large scale, low productive, semi-open dry sandy grassland-heathland ecosystems. Grazing improves habitat quality, supports typical species communities and represses invasive species

Henning, Katrin

Lorenz, Antje

Osterloh, Susanne

Seifert, René

Tischew, Sabine

English

Akademicka Platforma Czasopism

Ecological Questions 21/2015: 87 – 89 http://dx.doi.org/10.12775/EQ.2015.015Free-range grazing by large herbivores in degraded large-scale dry sandy grassland-heathland ecosystemsRené Seifert, Antje Lorenz, Susanne Osterloh, Katrin Henning, Sabine TischewAnhalt University of Applied Sciences, Department for Nature Conservation and Landscape Planning,  D-06406 Bernburg, Germany, email: r.seifert@loel.hs-anhalt.deAbstract. Free-range grazing by large herbivores combined with one-time mowing of over-aged heathlands offers an excellent man-agement tool to maintain and enhance biodiversity in degraded large scale, low productive, semi-open dry sandy grassland-heathland ecosystems. Grazing improves habitat quality, supports typical species communities and represses invasive species. Key words:year-round grazing, cattle / horses, habitat quality, foraging behaviour, Prunus serotina.1. Introduction and study areaLand-use abandonment in low-productive, but large scale dry sandy grassland-heathland ecosystems is a major prob-lem throughout Europe, causing a rapid grass and tree en-croachment, favouring invasive species and consequently threatening the typical species diversity of these NATURA 2000 habitats (e. g. Bakker et al., 2012). To counteract these trends and to improve the habitat quality, a new man-agement tool using free-range grazing by large herbivores (Heck cattle and Konic horses) combined with one-time mowing of over-aged heathlands was tested on a 800 ha pasture with long-term abandoned grassland and heathland habitats in the Eastern part of Germany (N51°46`22.246”, E12°21`34.448”). The advanced shrub and tree encroach-ment was drastically reduced by cutting before the grazing management was implemented. This study gives an over-view on effects of the grazing management on vegetation structure, plant species composition, soil parameters, the invasive native grass species Calamagrostis epigeios and invasive tree species Prunus serotina, habitat typical bird species and on large herbivores behaviour patterns.2. MethodsGrazing effects were evaluated by using before / after and with / without approaches on different spatial scales (Lorenz et al., 2013). Since 2008 the habitat quality pa-rameters (grasses, litter and bare soil) were investigated on 43 macroplots (100 m x 100 m) of grassland and heath-land habitats. Trajectories on plant community scale were analysed on microplots (5 m x 5 m) in the centre of each macroplot up to 2013. Soil samples were collected in 2009 and 2013. Total nitrogen contents were determined by run-ning an elemental analysis using the CNS-Analyser 2000 (LECO Instruments, DIN ISO 13878). The non-parametric Wilcoxon test was used to test for differences. Foraging behaviour of large grazers was quantified by direct animal observations. Habitat preferences for over-aged and mown heath were determined using the Ivlev`s Electivity Index (Jakobs, 1974). Regrowing shoots of the invasive tree spe-cies Prunus serotina were surveyed (counts of browsed / unbrowsed, annual growth, mortality) for six years until 2014. The non-parametric Mann-Whitney-U-Test was used to test for differences. Breeding territories of target bird species like Lullula arborea and Camprimulgus europaeus 88 René Seifert, Antje Lorenz, Susanne Osterloh, Katrin Henning, Sabine Tischewwere mapped in 2005, before the management was imple-mented, as well as in 2009 and 2012.3. ResultsLarge grazers improved habitat quality rapidly within the first four years, indicated by a decreased coverage of the invasive native grass species Calamagrostis epigejos, litter coverage and thickness but an increased percentage of bare soil in most of the habitats. Hence, plant species diversity increased remarkably: in former bushgrass stands from 18 to 48 species / 25 m², in dry sandy grasslands from 28 to 48 and in heath stands from 23 to 34 due to the immigration of species typical for nutrient-poor site conditions (Fig. 1).The total soil nitrogen content of all sites has been maintained at a low level (< 0.26 %) or even decreased significantly in heathland (p = 0.039) and dry grassland / heathland mosaic plots (p = 0.030). Cattle and horses gen-erally preferred grassland dominated habitats compared to heathlands. Particularly cattle preferred mown heath com-pared to only grazed ones and browsed more frequently on Prunus serotina than horses with up to 3 % of their daily intake. Studies on regrowing shoots of Prunus se-rotina indicated a high browsing efficiency of 89 % up to 98 % for the first years of management (2009 to 2011). As in the years before, in 2014 a shorter average shoot length (31.2 cm ± 32.1 SD, n = 59) compared to ungrazed shoots (125.4 cm ± 27.4 SD, n = 17) has been measured (p = 0.000). Furthermore a mortality of individuals with 58 % after six years of grazing has been observed. The management measures positively affected the number of breeding pairs of woodlark (Lullula arborea) and nightsjar (Camprimulgus europaeus), which increased from 37 to 45 and from 42 to 72, respectively (ÖKO & PLAN, 2013). 4. DiscussionExtensive free-range grazing by large herbivores in aban-doned low-productive dry grassland-heathland habitats improves vegetation structure by reducing biomass, par-ticularly in C. epigejos dominated stands, as well as litter layer and vegetation height (see also e. g. Schwabe et al. 2013). Consequently, species richness can be supported by grazing, especially if target species are still present as it was in our case (Bakker & Berendse, 1999; Bokdam & Gleichnam, 2000; Schwabe et al., 2013). Grazing seems to be suitable to maintain a low soil nitrogen status in regions with low atmospheric nitrogen deposition rates like our study area. In contrast, additional management measures are necessary in sites with high nitrogen deposition rates (Härdtle et al., 2006). To counteract the regrowth of cut-ted Prunus serotina individuals cattle browsing on young shoots and leaves seem to be suitable (see also Vanhelle-mont, 2009). Only in large Prunus serotina occurrences, additional measures are indispensable. Concluding, free-range large herbivore grazing with Heck cattle and Kon-ik horses is an effective management tool to restore and maintain dry sandy grasslands and heathlands.Figure 1. Development of average species numbers regarding ecological species groups in grazed bushgrass stands (Calamagrostis epigejos), dry sandy grasslands, dry heath communities and grassland/heath mosaics from 2008 to 2013. Repeat-ed-measures ANOVA was calculated to test for differences over time regard-ing the total species number within vegetation units. Degradation status: (ad) = advanced, (ld) = low. Asterisks mark significance levels: *** p ≤ 0.001, ** 0.01 ≥ p > 0.001, * 0.05 ≥ p > 0.01, n. s. p ≥ 0.05 89Free-range grazing by large herbivores in degraded large-scale dry sandy grassland-heathland ecosystemsReferencesBakker J.P., Berendse F., 1999, Constraints in the restora-tion of ecological diversity in grassland and heathland communities, Tree, 14: 63–68.Bakker J.P., Van Diggelen R., Bekker R.M. & Marrs R.H., 2012, Restoration of Dry Grasslands and Heathlands, [in:] J. van Andel, J. Aronson (eds) Restoration Ecolo-gy: The New Frontier, Blackwell Publishing: 173–188.Bokdam J., Gleichnam J.M., 2000, Effects of grazing by free-ranging cattle on vegetation dynamics in a conti-nental north-west European heathland, Journal of Ap-plied Ecology, 37: 415–431.Härdtle W., Niemeyer M., Niemeyer T., Assmann T. & Fot-tner S., 2006, Can management compensate for atmos-pheric nutrient deposition in heathland ecosystems?, Journal of Applied Ecology, 43: 759–769.Jakobs J., 1974, Quantitative Measurement of Food Selec-tion, A Modification of the Forage Ratio and Ivlev`s Electivity Index, Oecologia, 14: 413–417.Lorenz A., Tischew S., Osterloh S., Felinks B., 2013, Konzept für maßnahmenbegleitende naturschutzfa-chliche Erfolgskontrollen in großen Projektgebieten, Naturschutz und Landschaftsplanung 45: 365–372.ÖKO & PLAN, 2013, Naturschutzfachliche Erfolgskon-trolle von Managementmaßnahmen zum Erhalt und zur Entwicklung von FFH-Offenlandlebensraumtypen im NATURA 2000 Gebiet „Mittlere Oranienbaumer Heide“, Teil Brutvögel. Studie im Auftrag der Hoch-schule Anhalt, gefördert über ELER Sachsen-Anhalt, Az: 407.1.7–60128/323011000001.Schwabe A., Süss K. & Storm C., 2013, What are the long-term effects of livestock grazing in steppic sandy grass-land with high conservation value? Results from a 12-year field study, Tuexenia, 33: 189–212.Vanhellemont M., 2009, Present and future population dy-namics of Prunus serotina in forests in its introduced range, PhD thesis, Ghent University, Ghent, Belgium.

Free-range grazing by large herbivores in degraded large-scale dry sandy grassland-heathland ecosystems

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Free-range grazing by large herbivores in degraded large-scale dry sandy grassland-heathland ecosystems

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