Disturbance regimes in dry sandy grasslands – past, present and future

A number of sandy grassland habitats of interest for biodiversity conservation can be found in Europe. One such habitat is the threatened xeric sand calcareous grassland, which is home to a large number of endangered species. It is characterized by a discontinuous vegetation cover, mainly consisting of stress-tolerant species favoured by nutrient-poor and dry conditions. The xeric sand calcareous grassland habitat has declined during the last century due to intensification of farming, afforestation, abandonment, acidification and nutrient enrichment. Understanding the land use history has proven crucial for the conservation of biodiversity in the agricultural landscape. Land use was traced back to the 18th century, and land use history was compared with the amount of bare sand, lime content and P availability. Previous agricultural activity was found to have created these habitats in flat areas lacking natural disturbance. However, ploughing was probably not the factor retaining CaCO3 in the top soil. Instead, it seems very likely that it was the wind erosion, promoted by cultivation, which counteracted depletion by exposing the CaCO3 rich sand. The largest changes in land use took place more than 100 years ago. Areas that were recently cultivated had the highest levels of extractable P, which may pose a threat to biodiversity. The restoration potential of topsoil removal and soil perturbation in degenerated xeric sand calcareous grassland was investigated. Restoration actions performed in 2006 resulted in increased pH and reduced nitrogen availability. Early colonisation of the key species Koeleria glauca after both deep perturbation and topsoil removal was found. The proportion of target species in 2012 was 20% after topsoil removal, compared to 30% in target vegetation, and less than 1% in controls. Deep perturbation lead to 7% target species, while almost no effects of shallow perturbation could be seen. The increased pH after soil perturbation also resulted in increased species richness of bryophytes. Six red-listed beetle species associated with open, dry grasslands were found after soil perturbation, out of which four were found only in perturbated plots. The availability of propagules is a key factor for the re-establishment of plant species in grasslands after restoration. The seed rain and the seed bank of xeric sand calcareous grassland in southern Sweden were investigated with the aim to assess the potential contribution of soil seed bank and natural seed rain for the re-establishment of threatened plant species after habitat restoration. Most target species had a negligible persistent seed bank. Many target species were well-represented in the within-patch seed rain, but seed dispersal seemed to be very limited beyond the natal population

Natural Establishment of Specialist Plant Species after Topsoil Removal and Soil Perturbation in Degraded Calcareous Sandy Grassland

Specialist plant species in calcareous sandy grasslands are threatened by acidification and high nutrient levels in the topsoil. We investigated whether topsoil removal and soil perturbation in degraded sandy grasslands could lead to establishment of specialist species belonging to the threatened xeric sand calcareous grassland habitat. Restoration actions performed in 2006 resulted in increased soil pH and reduced nitrogen availability. We found early colonisztion of the perennial key species Koeleria glauca after both deep perturbation and topsoil removal, and high seedling establishment in topsoil removal plots 5 and 6years following the restoration treatment (2011-2012). After topsoil removal, overall vegetation composition in 2012 had developed toward the undegraded community, with target species accounting for 20% of the community after topsoil removal, compared to 30% in the undegraded vegetation, and less than 1% in untreated controls. Deep perturbation led to 7% target species, while there were almost no effects of shallow perturbation 6years following treatment. These results demonstrate that topsoil removal can promote colonization of target species of calcareous sandy grassland and highlights the importance of considering the regeneration niche for target species when implementing restoration measures

Conservation of sandy calcareous grassland: what can be learned from the land use history?

Understanding the land use history has proven crucial for the conservation of biodiversity in the agricultural landscape. In southern Sweden, very small and fragmented areas of the disturbance-dependent habitat xeric sand calcareous grassland support a large number of threatened and rare plants and animals. In order to find out if historical land use could explain variation in present-day habitat quality, the land use on eight such sites was traced back to the 18th century and compared with key factors such as the amount of bare sand, lime content and P availability. There was no support for the common explanation of the decline in xeric sand calcareous grassland being caused by abandonment of agricultural fields during the last century. Instead, fertilization history was the main explanation for the difference in depletion depth of CaCO3 seen between the sites. The decline in xeric sand calcareous grassland since the 18th century is most probably the result of the drastic changes in land use during the 19th century, which put an end to the extensive sand drift. Since cultivation was shown to have played an important role in the historical land use of xeric sand calcareous grassland, grazing alone may not be the optimal management option for these grasslands. Instead more drastic measures are needed to restore the high calcium content and maintain proper disturbance levels

Soil disturbance favours threatened beetle species in sandy grasslands

Soil disturbance is recognised as an important restoration measure for conserving biodiversity in sandy soils. We used a soil disturbance (ploughing) experiment in a sandy grassland as well as a semi-natural disturbance (slope erosion enhanced by cattle trampling) gradient on a sandy slope to test the soil disturbance effects on the ground-living beetle community. Both experimental disturbance and semi-natural disturbance favoured sandy grassland specialists, but there was no overall effect on beetle richness and abundance. Amara lucida and Harpalus spp. were favoured by disturbance while Calathus melanocephalus was disfavoured. Experimental ploughing significantly increased the proportion of red-listed species in disturbed plots compared to non-disturbed controls. In the semi-natural disturbance gradient we found that the beetle community on the disturbed slope differed from that of the flat areas, and there were tendencies for a higher proportion of red-listed species on the slope. We conclude that increasing the area of bare sand in sandy grasslands can have positive effects on many threatened species. Soil disturbance should thus be included as a regular measure in sandy grasslands under conservation management and as a measure to restore high biodiversity in areas where bare sand is rare

Biologisk mångfald

Klimatförhållandena har stor betydelse för om en art kan ha livskraftiga populationer på en viss plats, både genom direkta effekter på organismerna, och indirekta effekter på andra arter i ekosystemet, det vill säga arter som den är beroende av, predatorer och konkurrenter. Den biologiska mångfalden är viktig för ekosystemens förmåga att klara klimatförändringar. Vårt användande av landskapet kan komma att anpassas till klimatförändringarna, och detta kan få stora effekter på den biologiska mångfalden, utöver de direkta klimateffekterna. I Skåne är en viktig del av den biologiska mångfalden knuten till kusten, och förändringar av havsnivån är därför en viktig faktor för naturvårdsarbetet. Klimatförändringarna skapar ett behov av spridningsvägar mellan habitat av rätt kvalitet. Detta är nödvändigt eftersom omvandlingen av det skånska landskapet lett till att de flesta arternas habitat har minskat, försämrats och blivit starkt fragmenterade

Naturvård - segregerad från eller integrerad i jordbrukslandskapet?

Naturvårdens mål är att bevara biologisk mångfald (gener, arter och livsmiljöer) ochnaturliga ekosystemprocesser, men också att möta människors behov av att tillgodogöra sig de tjänster som naturen ger. Under de senaste åren har en polariserad debatt uppstått som ställer dessa målsättningar emot varandra. Sett ur ett bredare perspektiv är det dock möjligt att hitta lösningar som kombinerar bägge dessa målsättningar genom att identifiera synergier för ett effektivt naturskydd

A summary of the characteristics of the eight sites analyzed in this study, including the total area analysed and the area of xeric sand calcareous grassland (Natura 2000 habitat 6120) according to Olsson [32].

<p>Vegetation data comes from a survey in 2004-2005 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090998#pone.0090998-Poschlod2" target="_blank">[9]</a> and includes the total vegetation cover, as well as the cover of specialist species and nationally red-listed species as defined in Olsson and Ödman <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090998#pone.0090998-Olsson4" target="_blank">[55]</a>. In addition, the number of red-listed species per square meter (Nr/m²) is given. Means are displayed (± SD), and N denotes the number of analysed squares (1 m²) at each site. The dominant red-listed and specialist species were <i>Koeleria glauca, Dianthus arenarius</i> ssp <i>arenarius</i> and <i>Alyssum alyssoides.</i></p

The effects of pH and disturbance on the bryophyte flora in calcareous sandy grasslands

The unique flora and fauna of calcareous sandy grasslands is threatened by acidification, eutrofication and changed land use. Restoration experiments in such grasslands in southern Sweden, including deep and shallow soil perturbation, allowed us to examine the effects of pH and disturbance on the bryophyte flora. We also studied natural pH and disturbance gradients in order to compare the natural pH and disturbance variation with the responses of experimental manipulation. We found that increased pH due to soil perturbation resulted in increased species richness. However, in naturally disturbed areas, pH seemed to have a lower effect, and instead, the location of the site and possibly the site history had a larger influence on species richness. We also found that some of the species that were common at naturally high pH (mainly acrocarps) were favoured by experimental pH manipulation. Our results pointed out Syntrichia ruraliformis as a sensitive pH indicator, being almost exclusively restricted to pH values above 7. The species can also serve as an indicator of sand steppe vegetation

Map showing the existing xeric sand calcareous grassland sites in Skåne.

<p>Sites included in the study are represented by triangles and circles represent sites not included. Grey shading indicates forested land and unshaded represents open land. Scale bar represent 10: (1) Degeberga, (2) Everöd, (3) Klammersbäck, (4) Lyngsjö, (5) Rinkaby, (6) Ripa and (7) Vitemölla.</p