Long-Term Vegetation Change in Species-Rich Nardus Grasslands Of
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bioRxiv preprint doi: https://doi.org/10.1101/543512; this version posted February 8, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 Title 2 Long-term vegetation change in species-rich Nardus grasslands of 3 central Germany caused by eutrophication, recovery from acidification 4 and management change 5 6 Running head 7 vegetation change in Nardus grasslands 8 Article type 9 Research Article 10 11 Authors 12 Cord Peppler-Lisbach1, Nils Stanik2, Natali Könitz1, Gert Rosenthal2 13 1 Department of Biology, Earth and Environmental Sciences, Landscape Ecology Group, 14 University of Oldenburg, 26111 Oldenburg, DE 15 2 Department of Landscape and Vegetation Ecology, University of Kassel, 34127 Kassel, DE 16 17 Cord Peppler-Lisbach (Orcid ID: 0000-0001-8209-8539) 18 Nils Stanik (Orcid ID: 0000-0002-9717-3826) 19 20 Correspondence 21 Nils Stanik, Department of Landscape and Vegetation Ecology, University of Kassel, 34127 22 Kassel, DE, Email: [email protected] 23 Funding information 24 The study was funded with own resources of the Universities of Kassel and Oldenburg. 25 1 bioRxiv preprint doi: https://doi.org/10.1101/543512; this version posted February 8, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 26 Abstract 27 Questions 28 The impact of environmental changes on species-rich Nardus grasslands has been 29 documented from the Atlantic biogeographic region but not from Central Europe. Which 30 patterns and trends of community change in species-rich Nardus grassland of the Continental 31 biogeographic region occurred in past decades? Are patterns and trends similar across areas 32 within the Continental biographic region of Germany? Do they correspond to identified 33 changes in the Atlantic biogeographic region of Europe? 34 Location 35 East Hesse Highlands, Germany 36 Methods 37 In 2012/15, we re-surveyed vegetation relevés on quasi-permanent plots originally surveyed 38 between 1971 and 1986/87 and re-measured soil parameters. We tested for differences in 39 species frequency and abundance, mean Ellenberg indicator values, diversity measures and 40 soil variables. Nitrogen and sulphur deposition data were analysed to evaluate effects of 41 atmospheric pollutants. We used regression analyses to identify the contribution of 42 environmental drivers to changes in species composition. 43 Results 44 We found significant increases in soil pH, Ellenberg R and N values, species of agricultural 45 grasslands and grassland fallows. C:N ratio, Nardus grassland specialists and low-nutrient 46 indicators declined, while changes in species composition relate to changes in pH and 47 management. There was a strong decrease in sulphur and a moderate increase in nitrogen 48 deposition. Local patterns in atmospheric depositions did not correlate with local changes in 49 species composition and soil parameters. 50 Conclusion 51 The findings indicate significant overall eutrophication, a trend towards less acidic 52 conditions, and insufficient management and abandonment. This is widely consistent across 53 study areas and correspond to recent reports on vegetation changes and recovery from 54 acidification in the Atlantic biogeographic region. We strongly assume reduction in sulphur 55 deposition during recent decades to be a major driver of these changes combined with 2 bioRxiv preprint doi: https://doi.org/10.1101/543512; this version posted February 8, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 56 increased nitrogen deposition and reduced management intensity. This suggests a large- 57 scale validity of processes triggering changes in Nardus grasslands across Western and 58 Central Europe. 59 60 Keywords 61 acid grasslands, environmental change, eutrophication, habitat management, long-term 62 vegetation change, Nardus grasslands, nitrogen deposition, resurvey study, sulphur 63 deposition 64 65 Nomenclature 66 The nomenclature follows the German taxonomic reference list (GermanSL version 1.3) of 67 Jansen & Dengler (2008). 3 bioRxiv preprint doi: https://doi.org/10.1101/543512; this version posted February 8, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 68 Introduction 69 Semi-natural grasslands are of high importance for human well-being by providing 70 important ecosystem services and high biodiversity (Dengler et al. 2014; Hejcman et al. 2013). 71 They are, however, under increasing threat by effects of global change, e.g. land use change, 72 nitrogen deposition and climate change (Sala et al. 2000). Recent decades brought increasing 73 evidence for the important role of atmospheric depositions on grassland biodiversity, mainly 74 nitrogen (N) and sulphur (S) (Bobbink et al. 1998; Dupré et al. 2010). Consequences for 75 European semi-natural grasslands are the loss of species diversity, a change in species 76 composition and a decline of ecosystem functions (Bobbink et al. 2010; Phoenix et al. 2012; 77 Stevens et al. 2004). 78 Nardus grasslands (Nardetalia strictae, Peppler-Lisbach & Petersen 2001) are typical semi- 79 natural grasslands on strong to moderate acid soils in large parts of temperate Europe. In the 80 European context, they are classified as the priority natural habitat H6230* (Species-rich 81 Nardus grasslands on silicious substrates in mountain and submountain areas in Continental 82 Europe) of the EU Habitats Directive (Directive 92/43/EEC, European Council 1992) and are 83 assigned to several types in the EUNIS classification (e.g. E1.71, E1.72, E3.52, E4.31). 84 Moreover, they are often also referred to as or included in the type ‘acid grasslands’ (e.g. 85 Damgaard et al. 2011; Stevens et al. 2011b). Indicated by their high conservation status, 86 Nardus grasslands are highly endangered due to global change drivers mentioned above, 87 which apply to semi-natural grasslands in general. Among these drivers, abandonment and 88 land-use intensification have mainly triggered the decline of Nardus grasslands in Central 89 Europe since the late 19th century (Leuschner & Ellenberg 2017). Moreover, their preference 90 for poorly buffered, nutrient-poor soils makes them particularly vulnerable to processes of 91 eutrophication and acidification and thus to atmospheric depositions (Dupré et al. 2010; 92 Helsen et al. 2014). This also applies to Atlantic heathlands (Bobbink et al. 1998; Southon et 93 al. 2013), to which Nardus grasslands are floristically closely related. The goal of this study is 94 to investigate long-term changes in Nardus grassland of the Continental biogeographic 95 region and to assess the extent to which these drivers cause problems for the conservation of 96 this endangered habitat type. 4 bioRxiv preprint doi: https://doi.org/10.1101/543512; this version posted February 8, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 97 Eutrophication summarises the effects of nutrient enrichment, mainly of N or P and can be 98 attributed to agricultural fertilisation and atmospheric deposition (Bobbink et al. 2010; 99 Ceulemans et al. 2013). Eutrophication results in species losses due to competitive exclusion 100 of light-demanding, low-productive species (Bobbink & Hicks 2014; Ceulemans et al. 2013; 101 Hautier et al. 2009) and other changes in species and functional composition (Helsen et al. 102 2014). 103 Acidification is mainly driven by atmospheric deposition of N (NHy, NOx) and S (SOx), but 104 is also modified by local factors, e.g. bedrock and soil characteristics (Roy et al. 2014). It 105 results in decreasing pH values, leaching of base cations, Al3+ mobilisation, and higher ratios 106 of Al:Ca and NH4:NO3 (de Graaf et al. 2009; Stevens et al. 2009; Ross et al. 2012; Kleijn et al. 107 2008; Bobbink & Hicks 2014). These effects are considered to be responsible for the decline 108 and regional extinction of small-growing Nardus grassland and heathland species (like Arnica 109 montana) in the Netherlands (Fennema 1991; de Graaf et al. 1998). Additionally, soil 110 acidification may lead to reduced nutrient availability preventing the effects of N deposition 111 from being effective (Stevens et al. 2010b). 112 Studies analysing the effects of N deposition on acidic grasslands are predominantly from 113 the Atlantic biogeographic region of Europe (European Council 1992). Most commonly 114 reported effects are a decrease in total species richness, a decline in typical acid grassland or 115 heathland species adapted to low nutrient availability, an increase in graminoid cover but a 116 decrease in graminoid richness (Damgaard et al. 2011; Field et al. 2014; Payne et al. 2017; 117 Stevens et al. 2010a). Moreover, a decrease in forb and bryophyte cover and richness was 118 found (Maskell et al. 2010; Stevens et al. 2006). Ellenberg N values increased with increasing 119 N deposition (Henrys et al. 2011; Pakeman et al. 2016), whereas Ellenberg R values decreased 120 due to N deposition-driven acidification (Maskell et al. 2010). Regarding environmental 121 factors, soil pH was negatively correlated to N deposition rates, whereas C:N ratio showsed 122 a significant positive relationship with N deposition (Stevens et al.