Biodiversity in European grasslands under nutrient enrichment

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Mar 8, 2013 - Thomas 2000; Hinsinger 2001; Turner. & Haygarth 2001). ..... (Newman 1995; Carpenter et al. 1998; .... information we refer to Preston et al.

Biodiversity in European grasslands under nutrient enrichment Tobias Ceulemans

Faculteit Wetenschappen, K.U.Leuven Laboratory of Plant Conservation and Population Biology Kasteelpark Arenberg 31 3001 Leuven

Proefschrift voorgedragen tot het behalen van de graad Doctor in de Wetenschappen Promotor: Olivier Honnay Co-promotor: Roel Merckx

March 8, 2013 Chairman: Prof. dr. ir. Hans Jacquemyn Members of the jury: Prof. dr. Carly J. Stevens Prof. dr. ir. Steven Bouillon Prof. dr Koenraad Muylaert Dr. Aline Waterkeyn

© 2013 Faculteit Wetenschappen, Geel Huis, Kasteelpark Arenberg 11, 3001 Leuven Alle rechten voorbehouden. Niets uit deze uitgave mag worden vermenigvuldigd en/of openbaar gemaakt worden door middel van druk, fotokopie, microfilm, electronisch of op welke andere wijze ook zonder voorafgaande schriftelijke toestemming van de uitgever. Foto’s van Kasper Van Acker en Tobias Ceulemans. All rights reserved. No part of the publication may be reproduced in any form by print, photoprint, microfilm, electronic, or any other means without written permission from the publisher. Photos by Kasper Van Acker and Tobias Ceulemans.

dankwoord

Met dit doctoraal proefschrift wordt het einde ingeluid van een uitdagende onderzoeksperiode. Deze werd gekenmerkt door hoogtes en laagtes, zowel op academisch als op persoonlijk vlak. Tien jaar na mijn mama, heb ik ook ‘ons marein’ moeten afgeven. Aan de andere kant heb ik de kans gekregen om de trotste papa te worden van twee fantastische zonen, Tjores en Anthos.Vooreerst wil ik hun bedanken voor al de herinneringen die deze periode intensief hebben gekleurd. Op academisch vlak ben ik vooral aan mijn promotor Olivier veel dankbaarheid verschuldigd. Voor het enthousiaste onthaal van een kandidatuur student met een onderzoeksidee, voor het opgebrachte geduld ondanks enkele ‘kleurrijke’ studentikoze episodes en voor het vaak onvoorwaardelijke vertrouwen dat je in me hebt gesteld als onderzoeker. Hetzelfde kan gelden voor mijn copromotor Roel en mijn coauteurs Carly en Bart, die onmiddellijk mee dit project wilden vormgeven. Daarnaast wil ik ook Lydia, die met het nodige professionalisme de lay-out van dit proefschrift heeft vormgegeven, in de bloemetjes zetten. Tenslotte wil ik ook mijn familie, vrienden, collega’s en jury bedanken. Aangezien ik heb moeten vaststellen dat onderzoek maar net zo goed kan functioneren als het welbehagen van de onderzoeker en de stimulerende omgeving van de werkplaats, ben ik hun dan ook veel verschuldigd. Op de laatste pagina van dit proefschrift heb ik daarom een poging ondernomen om jullie allemaal een eervolle vermelding te geven. Ik hoop dat ik hierbij niemand vergeten ben… Ik wens af te sluiten met de hoop dat dit proefschrift een bijdrage zal leveren aan de ontwikkeling van duurzame landbouw en een efficiënt natuurbehoud. Leuven, March 26, 2013.

table of contents

Chapter 1: Introduction

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1.1 Biodiversity in European grasslands 1.2 Nutrient pollution of grasslands 1.2.1 Nitrogen and phosphorus 1.2.2 Biodiversity loss following nutrient enrichment 1.2.2.1 Eutrophication 1.2.2.2 Acidification 1.2.2.3 Disruption of below-ground mutualisms 1.3 Aims and outline of this thesis

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Case-study 1: Land use and vegetation characteristics after 5 decades of change in hay meadows and grassheaths of the Demervalley (Belgium)

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Chapter 2: A trait based analysis of the role of phosphorus vs. nitrogen enrichment in the loss of grassland plant species across Northwestern Europe

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2.1 Introduction 2.2 Methods 2.2.1 Field methodology 2.2.2 Laboratory methodology 2.2.3 Collection of plant trait data 2.2.4 Statistical analysis 2.3 Results 2.4 Discussion 2.4.1 Effects of n and p on the occurence of plant species 2.4.2 The mediating role of plant traits 2.5 Conclusions

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Case-study 2: Seedling establishment of two grasslands species under elevated levels of N and P

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Chapter 3: Plant species loss from European semi-natural grasslands following nutrient enrichment -Is it nitrogen or is it phosphorus?

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3.1 Introduction 3.2 Materials and methods 3.2.1 Field and laboratory methods 3.2.2 Deposition data 3.2.3 Statistical analysis 3.3 Results 3.4 Discussion 3.5 Conclusions

68 70 70 72 73 75 79 84

Case study 3: Arbuscular mycorrhizal fungi in European grasslands

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Chapter 4: Soil phosphorus constrains biodiversity conservation across European grasslands

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4.1 Introduction 4.2 Materials and methods 4.2.1 Data collection 4.2.2 Statistical analyses 4.3 Results and discussion 4.4 Conclusions

100 100 100 104 105 110

Chapter 5: Discussion and general conclusions

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5.1 Is it nitrogen or is it phosphorus? 5.2 Current research limitations 5.3 Research perspectives 5.4 Biodiversity in European grasslands under nutrient enrichment 5.5 Recommendations

115 118 121 123 125

Summary Samenvatting References Appendices Publications Contributors

129 135 141 161 179 185

Chapter 1: Introduction

View on12 the Nardus grasslands (top) and calcareous grasslands (bottom) of Kanne (Belgium, 2008)

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1.1 Biodiversity in European grasslands

Chapter 1

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Gentianella germanica in calcareous grassland (Wonck, Belgium, 2011) Detail of calcareous grassland with Polygala vulgaris and Serapias lingua (Rosnay, France, 2010) Detail of hay meadow with Anacamptis laxiflora and Leucanthemum vulgare (Rosnay, France, 2011) Detail of Cirsium dissectum in wet Nardus grassland (Saulnay, France, 2011)

Prior to human settlement in Europe, the extent of natural grassland habitat was limited to clearings occurring in a forest landscape maintained by grazing of mega-herbivores (Vera 2000; but see Bond 2005). With the exception of vegetation types on very dry and shallow soil, extremely wet soil and on alpine slopes, contemporary European grasslands are anthropogenous in origin. Indeed, large scale deforestation for timber and firewood, and the establishment of grazing areas and hay meadows to sustain domesticated livestock, resulted in the expansion of open areas where grassland species could colonize (Poschlod &Wallisdevries 2002;Veen et al. 2009). As continuous human pastoral tradition and hay making is a prerequisite for the persistence of these habitats whereas the species composition is largely spontaneous; these vegetation types are called seminatural grasslands. Historically, seminatural grasslands made up a large part of the European agricultural landscape, traditionally managed by (intermittent) grazing and/or mowing (Web 1998; Veen et al. 2009). As a consequence of continuous removal of biomass and the very limited supply of fertilizers, traditional semi-natural grasslands are typically low productive, occurring on

nutrient poor soils. Agricultural and industrial developments in the mid 20th century, however, brought about a large scale loss of traditional grassland management. Primary changes resulted from the introduction of industrial synthesis of ammonia (Haber-Bosh procedure, Haber & Bosh 1910; Cleland & Harpole 2010), and the intensive mining of rock-P for the manufacturing of super-phosphate. This alleviated the shortage of mineral N and P fertilizers in Europe. Subsequently, the management of a large number of European grasslands intensified through wide spread application of fertilizers, often in concert with frequent ploughing and reseeding with highly productive grass species.This was necessary to sustain food production for high performance livestock breeds (Veen et al. 2009). Alternatively, due to difficulties associated with cultivating intensive grasslands on extremely poor soil, and economic difficulties of wool production competing with the import of cheap cotton, a large number of semi-natural grasslands were subject to abandonment of traditional management. This caused scrub encroachment and succession to forests (Webb 1998,Veen et al. 2009) Others were converted into economically more profitable forest plantations (Piessens et al. 2005, Veen et al. 2009).

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Despite intensification or abandonement of agricultural practises during the past decades, semi-natural grasslands are still amongst the most biodiverse habitats in Europe, exhibiting a large variety of insect species, specific grassland fungi and with up to 50 plant species per square meter (Roem & Berendse 2000; Poschlod & Wallisdevries 2002; Fagan et al. 2008; Öster 2008; Phoenix et al. 2008). However, owing to the mentioned ongoing land use changes in European landscapes, most of the remaining semi-natural grassland are restricted to small and isolated patches of high conservation interest.Aside from possible deleterious effects of habitat fragmentation on the species in these areas (e.g. Piessens et al. 2004; Meekers & Honnay 2011), grasslands with adjacent arable land are also frequently characterized by considerable loss of habitat quality, for instance through a varying degree of agricultural runoff and seepage of biocides and fertilizers (Tilman et al. 2001).

1.2 Nutrient pollution of grasslands

1.2.1 Nitrogen and Phosphorus Nitrogen (N) and phosphorus (P), together with carbon,oxygen,hydrogen

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and sulfur, are the main essential elements for plant development as they serve as building blocks for proteins, energy conveying molecules, DNA and ribosomal RNA. Whereas the supply of N and P in ecosystems worldwide was historically relatively low, high rates of fertilization and atmospheric deposition of volatilized nitrogenous compounds from combustion processes and agriculture, cause continuous input of nitrogen and phosphorus in the terrestrial and aquatic environment (Newman 1995; Smith et al. 1999; Galloway et al. 2008). This is reflected in the unprecedented increment of the respective anthropogenic N and P inputs in the biosphere since the beginning of the industrial revolution (from 15.3 to 259 Tg N yr-1 and 7, mainly in calcareous grasslands), exchange of base cations for protons at the soil absorption complex (at intermediate pH levels) and solubilization of aluminium (Al) sesquioxides (at [email protected]@s
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M&M The study area was located in the valley of the river Demer in the region of Aarschot (50°59’N and 4°50’E), in the northeast of Vlaams-Brabant (Belgium, Fig 1). The topography of the landscape is mainly determined by tertiary formations which protrude as hills in the region and are characterized by oak and birch forests and grassy heathlands akin to Nardus grasslands. In between the hills, the alluvial plain of the Demer

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mainly consists of sandy clay deposits which are historically dominated by hay meadows. To revisit the historical vegetation records, we geo-referenced the old topographic map (1:20.000) with the plot location using unchanged land marks such as cross-roads, churches and chapels. However, we paid particular attention to unchanged grassland edges with trees and ditches, occurring in the same place on both the old topographic map and recent maps. The frequent occurrence of these historical smallscale landscape elements in the study area made it possible to relocate the grassland records with an acceptable degree of accuracy (estimated at an error of +/-25m). Geo-referencing was performed using the software package MapInfo Professional (version 8.0, Pitney Bowes Software, New York, U.S.A.). Data collection took place in July and August 2011. To quantify the land use changes, the present land use was determined by means of topographic maps and field observations. A total of 48 grassheaths and 28 hay meadows were revisited. In a randomly selected subset of grassheaths (N=18) and hay meadows (N=10) we made a complete vegetation description covering the same plot of the historic record (% cover by eye estimation in a plot of 10mx10m; Fig 1). Current gardens and arable fields were not considered for selection as they do not consist of spontaneous vegetation.

Fig 3: Shifts in species composition between 1956-1957 and 2011 in a DCA ordination space. Historical and present surveys of the plots are connected by arrows. Both hay meadows and grassheaths showed a significant displacement along the first axis (Z=2.6, P=0.009 and Z=3.2, P

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