Soil microbial community structure in European forests in relation to forest type and atmospheric nitrogen deposition.

Berlin

2011

S. 37-50

BandaufführungSonderdruck

10859S

172159

The objective of the present study was to evaluate the combined effect of vegetation and N deposition on microbial community composition in forest soils. For this, microbial biomass and community structure were assessed by ester linked fatty acid methyl ester (EL-FAME) analyses for 12 European forest sites representing different forest types (coniferous/deciduous) and differing in annual N loads (2 40 kgNha.1). Microbial community composition was affected by vegetation as indicated by a higher proportion of the marker for arbuscular mycorrhiza (AM) fungi 16:1 11ù in deciduous forest soils (1.2% 5.7% of total EL-FAMEs) compared to acidic coniferous forest soils (0.5% 1.6%). The two pine forest sites investigated showed the highest proportion of fungi (up to 28% of total EL-FAMEs) and the lowest proportions of Gramnegative and Gram-positive bacteria of all study sites. Nitrogen deposition rates were highly correlated with the ratios of cyclopropyl fatty acids to their precursors (r=0.82; P<0.01) and of bacteria to fungi (r=0.71; P<0.05). The two sites with the highest N deposition (.32.3 kgNha.1a.1) were depleted in the marker fatty acids for AM fungi and other fungi. Our findings suggest that vegetation has a pronounced effect on microbial community structure, but this effect is masked by high N inputs (>30 kgNha.1a.1).Keywords Ester linked fatty acid . Soil microbial communities . Stress . Forest soils . Microbial biomass . N deposition