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Soil microbial biomass and activity: the effect of site characteristics in humid temperate forest ecosystems
Author(s) -
Friedel Jürgen K.,
Ehrmann Otto,
Pfeffer Michael,
Stemmer Michael,
Vollmer Tobias,
Sommer Michael
Publication year - 2006
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.200521763
Subject(s) - biomass (ecology) , forest floor , soil water , environmental science , soil organic matter , organic matter , abiotic component , soil quality , environmental chemistry , agronomy , chemistry , soil science , ecology , biology
Microbial biomass, respiratory activity, and in‐situ substrate decomposition were studied in soils from humid temperate forest ecosystems in SW Germany. The sites cover a wide range of abiotic soil and climatic properties. Microbial biomass and respiration were related to both soil dry mass in individual horizons and to the soil volume in the top 25 cm. Soil microbial properties covered the following ranges: soil microbial biomass: 20 µg C g –1 –8.3 mg C g –1 and 14–249 g C m –2 , respectively; microbial C–to–total organic C ratio: 0.1%–3.6%; soil respiration: 109–963 mg CO 2 ‐C m –2 h –1 ; metabolic quotient ( q CO 2 ): 1.4–14.7 mg C (g C mic ) –1 h –1 ; daily in‐situ substrate decomposition rate: 0.17%–2.3%. The main abiotic properties affecting concentrations of microbial biomass differed between forest‐floor/organic horizons and mineral horizons. Whereas microbial biomass decreased with increasing soil moisture and altitude in the forest‐floor/organic horizons, it increased with increasing N tot content and pH value in the mineral horizons. Quantities of microbial biomass in forest soils appear to be mainly controlled by the quality of the soil organic matter (SOM), i.e. , by its C : N ratio, the quantity of N tot , the soil pH, and also showed an optimum relationship with increasing soil moisture conditions. The ratio of C mic to C org was a good indicator of SOM quality. The quality of the SOM (C : N ratio) and soil pH appear to be crucial for the incorporation of C into microbial tissue. The data and functional relations between microbial and abiotic variables from this study provide the basis for a valuation scheme for the function of soils to serve as a habitat for microorganisms.