Soil chemistry of local vegetation gradients in sandy calcareous grasslands

Abstract

Acidification and N-deposition are continuous processes that alter the composition of plant communities. We investigated vegetation transitions in sandy grasslands and tested two hypotheses: (1) a shift from vegetation dominated by Koeleria glauca to one dominated by Corynephorus canescens is due to acidification and (2) a shift from vegetation dominated by K. glauca to one dominated by Arrhenatherum elatius is due to increased mineral-N. The occurrence of K. glauca and C. canescens followed pH shifts strikingly well. However, the pH varied considerably between sites, and we found that differences in preference for bare sand may be important for the coexistence of these two species at both high and low pH. In 75% of the gradients, the dominance of A. elatius was related to high content of mineral-N. Most species preferred lime-rich soils and we concluded that both N-enrichment and acidification may lead to loss of species in calcareous sandy grasslands.

Soil disturbance as a restoration measure in dry sandy grasslands

“…In another study of xeric sand calcareous grasslands in southern Sweden, a high N concentration was found to induce a shift from calcareous grassland vegetation towards vegetation dominated by the grass Arrhenatherum elatius (Mårtensson and Olsson 2010). When investigating the effect of nutrient addition on a nutrient-poor, calcareous inland sand ecosystem in Germany, Storm and Süss (2008) found that the above-ground production of vascular plants was doubled following N and NP treatments, and that the cover and/or height of nearly all the species investigated increased following high doses of N. P application alone had little effect, which may indicate that the system in question was N limited.…”

“…Olsson et al (2009) found a high number of red-listed plant species in nutrient-poor sandy grasslands, but the highest numbers were found on neutral to slightly alkaline soils, and a few species seemed to be restricted to alkaline soils. A later survey of the same grasslands revealed that decreasing pH brought about a shift from calcareous grassland vegetation towards heath vegetation dominated by Corynephorous canescens (Mårtensson and Olsson 2010). The grass heath (Natura 2000 code 2330) is also a protected vegetation type, but in Sweden this vegetation type is more abundant and has fewer red-listed species than xeric sand calcareous grassland (Olsson et al 2009).…”

“…Of particular interest is the threatened habitat xeric sand calcareous grassland (Natura 2000 code 6120, 2002/83/EC Habitat Directive), which is home to a large number of red-listed and endangered species of vascular plants (Mattiasson 1974;Olsson 1994;Eichberg et al 2010), bryophytes (Tyler 2005), fungi (Hansson and Jeppson 2005;Olsson et al 2010) and invertebrates (Ljungberg 1999). During the past century there has been a decrease in the area and species richness of these grasslands, caused mainly by changes in land use (Tyler 2003;Mattiasson 2009;Eichberg et al 2010), and they are further threatened by acidification (Olsson et al 2009;Mårtensson and Olsson 2010) and nutrient enrichment (Tyler 2005;Storm and Süss 2008;Mårtensson and Olsson 2010). There are 423 sites with xeric sand calcareous grasslands listed in the EUNIS database (European Environment Agency 2011), occurring in 11 European countries; Germany and Poland hold the highest number of sites.…”

Immediate responses in soil chemistry, vegetation and ground beetles to soil perturbation when implemented as a restoration measure in decalcified sandy grassland

“…The lowest concentrations of extractable PO 4 -and N found in the deep perturbation plots were 1.69 lg/g soil and 0.11 lg/g soil respectively. The corresponding lowest concentrations of PO 4 -and N found in target plots in the study area were 0.73 lg/g soil and 0.20 lg/g soil respectively (Mårtensson and Olsson 2010), suggesting that the recolonization was not limited by the PO 4 -availability but could have been limited by the N availability. The most successful colonizer after both kinds of perturbation was C. canescens, covering over 35% of the perturbated plots and only 7% of the control plots.…”

“…The Ellenberg index is, however, only valid under competition, and could change when competition is low. When studying pH gradients and vegetation on sandy soils in southern Sweden, Mårtensson and Olsson (2010) found that C. canescens occurred, and sometimes dominated, on soils with a high pH. Olsson et al (2009) found that C. canescens also occurred frequently in plots with a very high pH, and in particular in recently disturbed areas.…”