Abstract: Tea (Camellia sinensis L.) is one of the most important and traditional economic crops widely cultivated in the subtropical regions of China, which are usually developed from forestland. Soil enzyme activity is an important indicator of soil fertility and nutrient transformation. The purpose of this study is to investigate the seasonal dynamic characteristics of soil properties and enzyme activities of different planting patterns in Wuyishan city, and to provide theoretical basis for reasonable evaluation of soil ecological effects of organic tea cultivation. In this paper, three different planting patterns (forestland, conventional and organic tea gardens) were selected as the research objects. Soil samples were collected in May, August, November and February from 2021 to 2022. The soil properties and enzyme activities (urease, nitrate reductase, polyphenol oxidase, catalase, invertase and acid phosphatase) were determined in different seasons, and the dynamic changes with seasons were also investigated. The results show that: comparing with the forestland, the contents of soil ammonium nitrogen, total phosphorus, available phosphorus and available potassium increased significantly in the conventional tea garden, while the total potassium and pH decreased significantly. Compared with the conventional tea garden, the soil organic matter and total nitrogen contents increased significantly in the organic tea garden. The soil total phosphorus, available phosphorus, total potassium and available potassium contents decreased significantly. The soil pH also increased, and the proportion of soil nutrients was more coordinated. The effects of planting pattern and season and their interactions on urease and peroxidase activities were significant. Compared with the forestland, the soil urease, polyphenol oxidase, catalase and acid phosphatase activities decreased by 12.05% to 63.55% in the conventional tea garden, while urease activities significantly increased by 324.95% in the organic tea garden, and the soil nitrate reductase activities were not changed by planting mode. In general, the soil urease, polyphenol oxidase, invertase and acid phosphatase activities were significantly higher in summer and autumn (May and August) than those in winter and spring (November and February). The highest soil nitrate reductase and catalase activities were found in spring (February). The results of permutational multivariate analysis of variance show that the effect of planting pattern on the overall soil physical and chemical properties was much greater than that of seasonal changes. Redundancy analysis shows that soil environmental factors explained 77.03% of the variation in soil enzyme activity, and the soil organic matter, total nitrogen, ammonium nitrogen, total phosphorus, soil available phosphorus, total potassium, available potassium and pH were the main driving factors of soil enzymes. In summary, the conversion of forestland into tea gardens has a significant impact on soil properties and enzyme activities. Conventional planting leads to the accumulation of available phosphorus and potassium in tea garden soil and the decrease of soil enzyme activity, while organic planting improves soil enzyme activity and enhances soil carbon and nitrogen nutrient supply capacity, and thus is beneficial for maintaining a sustainable ecosystem in tea garden soil.

Key words: planting patterns, seasonal dynamic, soil physical and chemical properties, soil enzyme activities