『Abstract
　The effects of site exposure (microclimate) and forest management (thinning) on fungal-to-bacterial (F:B) respiratory ratio and N2O emission from forest floor and Ah layer samples were studied at untreated and thinned beech forests. Microclimate effects were studied by selecting sites facing north-east (NE) or south-west (SW). The F:B respiratory ratio was estimated using substrate-induced respiration in combination with inhibitors either affecting fungi or bacteria. N2O production was evaluated after moistening samples initially pre-incubated at different moisture levels to 100％ of the water holding capacity (WHC). F:B respiratory ratios were significantly affected by microclimate and thinning, with site exposure having the strongest effect on fungal-to-bacterial ratio and N2O production both for the forest floor and the Ah layer. Significantly more N2O was produced from soils pre-incubated under low (15％ WHC) moisture conditions as compared to soils pre-incubated under air dry (5％ WHC) or wet conditions (30-60％ WHC). A positive correlation between N2O emission and F:B respiratory ratio for Ah layer samples and a negative correlation between bacterial substrate induced respiration (SIR) and N2O emission for both Ah layer and forest floor samples indicated that net N2O production was the result of predominantly fungal N2O production and predominantly bacterial N2O consumption. The latter hypothesis was further supported by increased N2O emission from samples treated with bacterial inhibitor.

Keywords: Forest soils and management; Thinning; Fungal-to-bacterial ratio; Nitrous oxide emission; Streptomycin; Cycloheximide』

Introduction
Methods
　Experimental site
　sampling of the forest floor and Ah layers
　Determination of the fungal-to-bacterial ratio and inhibitor optimization
　Pre-incubation at different soil moisture
　Determination of N2O production
　Analytical methods
　　Gas analysis
　Statistical analysis
Results
　Inhibitor optimization
　Fungal-to bacterial ratio
　Effect of pre-incubation at different water contents on N2O production
　N2O emission after moistening to 100％ WHC
　Relationship between F:B respiratory ratio and N2O production
　Effect of selective inhibitors on N2O emission from soils after moistening to 100％ WHC
Discussion
　Optimization of inhibitors concentrations and fungal-to-bacterial ratio in forest floors and Ah layer soils
　Effect of site exposure and forest management on fungal-to-bacterial ratio
　Effect of pre-incubation at different soil moisture on N2O emission
　N2O emission after moistening to 100％ WHC
　Linkage between fungal-to-bacterial ratio and N2O emission after moistening
　Inhibitor effect on N2O emission
Conclusions
Acknowledgments
References