Objective To determine the relationship between soil enzyme activities and carbon inputs by experimentally altering the quantity of forest floor litter.

Method In an age sequence of natural Quercus aliena var. acuteserrata forests (stand age approximately 40 years, 80 years, and>160 years) in the Baotianman Nature Reserve, He'nan Province, three treatments were applied, including doubling of litter (LA), litter removal (LR) and the control (CK). Measurements were made on soil physiochemical properties, microbial biomass, and activities of oxidative enzymes (phenol oxidase and peroxidase) and hydrolytic enzymes (β-glucosidase and β-1, 4-N-acetylglucosaminidase).

Result The stand age affected only the β-1, 4-N-acetylglucosaminidase; its activity decreased with the increasing stand age. The litter treatments had no significant effect on oxidative enzymes, but the activity of β-glucosidase increased with the increasing litter inputs, ranking in the order of LA > CK > LR. The change pattern of microbial C/N ratio (characterization of microbial structure) were not consistent with that of specific enzyme activity (microbial function).

Conclusion The changes in the quantity of carbon inputs can affect soil enzyme activities by modifying soil environmental factors and nutrient inputs, but the effects vary among enzymes. Forest stand age is also a factor affecting soil enzyme activities.