Differences in rhizosphere enzyme activities and microbial metabolic limitations among overstory trees, understory shrubs and herbs are regulated by growing season

We measured the activities of seven hydrolytic enzymes related to carbon (C), nitrogen (N), and phosphorus (P) acquisition in the bulk soils and the rhizosphere soils of overstory trees, understory shrubs (Loropetalum chinense, Adinandra millettii, Eurya muricata), and herbs (Woodwardia japonica, Dryopteris atrata, Dicranopteris dichotoma) in pure plantations of Cunninghamia lanceolata, Pinus massoniana, and Pinus elliottii in subtropical China. Sampling was conducted during the slow growing season (April) and vigorous growing season (July).