The relationship between soil bacteria substrate utilisation patterns and the vegetation structure in temperate forests

The aim of the study was to explore the relationship between the functional diversity pattern of soil bacteria and the vegetation diversity and structure in temperate forests (Poland). Pine-dominated forests occur on soils with lower pH, fewer nutrient contents (P, Na, Mg, Mn and K) and higher C/N and C/P ratios than beech-dominated forests and mixed broadleaved forest with hornbeam and ash. Both forest type and soil horizon (O and A) strongly influenced bacterial catabolic activity and the number of substrates decayed on Biolog® ECO plates. Pine forest soil bacteria were less active and less functionally diverse than those in deciduous forest soils. The community-level physiological profiles (CLPPs) were dissimilar (one-way analysis of similarities) between pine and mixed deciduous forests, but only in the O soil horizon. Carboxylic acids primarily contributed to the average dissimilarity in CLPP between forests (the similarity percentage procedure); these substrates are preferentially used by pine forest soil bacteria. The canonical correspondence analysis indicated that soil pH, nitrogen and organic matter contents and plant diversity index H′plant were related to bacterial CLPP in the O soil horizon. Only for the soil O horizon, the Mantel test showed a clear relationship between vegetation structure and bacterial CLPP