LAUSR

Abstract Research on the changes of soil carbon (C)- and nitrogen (N)-cycling enzyme activities within aggregate fractions is essential for improving our understanding of soil organic matter (SOM) dynamics in agricultural ecosystems. However, the short- and long-term implications of the conversion of abandoned croplands to tea (Camellia sinensis L.) plantations on enzyme activities associated with aggregate fractions remains poorly understood. In the present study, we hypothesized that (i) the concentrations of soil organic C and total N would increase as the tea plantations continued to age, and (ii) the potential of SOM decomposition would differ with the stage of tea cultivation, as there would be significant changes in the activities of soil C- and N-cycling enzymes over time. The activities of β‑glucosidase, invertase, urease, and protease were analyzed in different size fractions of soil aggregates that were collected from 0 to 20 cm depth in four tea plantations with the same cultivar (Sichuan tea) of various ages (16-, 23-, 31-, and 53-years) in the hilly areas of Western Sichuan, China. The aggregates were separated using a dry-sieving procedure into four fractions, namely, large (>2 mm), medium (2–1 mm), small (1–0.25 mm) macro-aggregates, and micro-aggregates (