Objective The aims were to explore the difference of fine root decomposition rate in different stands, and to test the strength of the main field effect of fine root decomposition of different tree species and the driving factors of main field effect.

Method Four subtropical plantation tree species, Cunninghamia lanceolata, Michelia macclurel, Pinus massoniana and Schima superba, were selected as the research objects. The litter decomposition bag method was used to study the decomposition rate of fine roots of different tree species in different plantations, and the effects of initial chemical quality of different fine roots and soil environment on the decomposition rate of fine roots were analyzed.

Results The initial chemical quality of fine roots, stand environment and their interaction had significant effects on the decomposition rate of fine roots. Affected by the initial chemical quality of fine roots, the decomposition constant (k value) of fine roots of Michelia macclurel and Pinus massoniana was larger in all stands, while the k value of fine roots of Cunninghamia lanceolata and Schima superba was smaller. The initial carbon content of fine roots was negatively correlated with the decomposition rate of fine roots, and the initial nitrogen and phosphorus contents of fine roots were significantly positively correlated with the decomposition rate of fine roots. The effects of soil nutrients on the decomposition of fine roots varied from species to species, and the fine roots of Michelia macclurel were significantly affected by soil nutrients in each stand. The home-field advantage of fine roots of the four tree species was significantly different. Compared with soil ability, the home-field effect was significantly affected by litter quality index, and the P content of fine roots and soil was significantly negatively correlated with the home-field effect of fine root decomposition.

Conclusion The nutrient status of fine roots and stands jointly affect the decomposition of fine roots and its main field effect. The nutrient status of fine roots is an important driving factor for the decomposition of fine roots and its main field effect at the local scale. In the future, fine root and stand nutrients should be considered comprehensively when studying the decomposition and carbon cycle processes at the local scale.