Soil respiration and FDA hydrolysis following conversion of abandoned agricultural lands to natural vegetation in central Korea

Soil respiration and the hydrolysis of fluorescein diacetate (FDA) as a measure of total microbial activity were investigated in central Korea, at three sites that had been changed from abandoned agricultural lands to natural vegetation: rice field conversion to forest (RF), crop field conversion to shrub (CS), and indigenous forest (IF). Seasonal variations in soil respiration were affected by soil temperature and, to a lesser extent, by photosynthetically active radiation (PAR) and soil moisture. The mean annual rate of soil respiration (g CO₂ m^-2 hr^-1) was highest at CS (0.36), followed by IF (0.29) and RF (0.28), whereas the total annual soil respiration (kg CO₂ m^-2 yr^-1) was 2.82 for CS, 2.46 for IF, and 2.40 for RF. Mean annual FDA hydrolysis (μg FDA min ^-1 g^-1 dry soil) was higher at RS (4.56) and IF (4.61) than at CS (3.65). At all three land-use change sites, soil respiration was only very weakly correlated with FDA hydrolysis.