Objective This paper aimed to provide suggestions for the management of urban ecosystems and urban planning by investigating the changes of soil extracellular enzymes in the rhizosphere and non-rhizosphere of vegetation in agricultural land and urban green space under heat stress.

Method The 0 ~ 10 cm soil samples belowground in the rhizosphere and non-rhizosphere of Oryza sativa L. (OS), Metasequoia glyptostroboides (MG) and Cinnamomum camphora (CC) in Fengxian District of Shanghai, China, were collected and the activities of soil sucrase, soil urease and soil alkaline phosphatase were analyzed. The soil physical and chemical indicators and the number of microbes were also analyzed.

Result The soil enzyme activities in the rhizosphere were higher than those in the non-rhizosphere in both agricultural land and urban green space at 20℃, while the soil enzyme activities in the rhizosphere were lower than those in the non-rhizosphere at 40℃ which was simulated the temperature of heat stress. The three soil enzyme activities changed significantly as the temperature increased (P < 0.05). The soil sucrase activities in the rhizosphere of CC decreased significantly with the increasing temperature while increasing significantly in the non-rhizosphere. The soil urease activities in the non-rhizosphere of MG decreased significantly. The soil alkaline phosphatase activities in the rhizosphere of the three plants decreased significantly but increased slightly in the non-rhizosphere (P > 0.05). During the short-term simulation of heat stress, the soil enzyme activities in MG and CC were higher than those in OL. CC had higher soil sucrase activities and soil urease activities than MG at 20℃, but its soil sucrase activities in the rhizosphere and its soil urease activities in the non-rhizosphere were significantly lower than that of MG at 40℃. Compared to MG, the soil alkaline phosphatase activity of CC was lower (P > 0.05) at 40℃. The soil physical and chemical indicators and the number of microbes were significantly different among the three plant sites. No significant correlation between soil enzyme activities and soil nutrients, also among the three soil enzyme activities were found in this study.

Conclusion This study reveals the complex effects of heat stress on soil extracellular enzyme activities in different land use patterns. The soil enzyme activities in urban green spaces with MG and CC as the dominant plants were higher than those in agricultural land with OS as the dominant plant under the short-term simulation of heat stress.