Rising atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are the main global change drivers. Soil ectoenzymes play an important role in maintaining soil ecosystem services. Exploring the responses of soil ectoenzymes to elevated CO2 and O3 concentrations is important for combating global climate change. In this study, we simulated elevated CO2 concentrations (+200 μmol·mol-1, eCO2), elevated O3 concentrations (0.04 μmol·mol-1, eO3), and their combination (eCO2+eO3) in open-top chambers (OTCs), and investigated the responses of rhizospheric soil ectoenzyme activities. The results showed that eCO2 significantly increased the β-D-Glucosidase (βG) activity by 73.0%, and decreased that of polyphenol oxidase (PHO), peroxidase (PEO), and acid phosphatase (AP) by 48.9%, 46.6% and 72.9% respectively, but did not affect that of cellulose hydrolase (CBH) and β-N-Acetylglucosaminidase (NAG). eO3 significantly reduced the activities of CBH and AP by 34.2% and 30.4%, respectively. The activities of PHO and AP were reduced by 87.3% and 32.3% under the eCO2+eO3 compared with the control, respectively. Results of the principal coordinate analysis, permutation multivariate analysis of variance and redundancy analysis showed that both elevated CO2 and O3 significantly affected soil ectoenzyme activities, with stronger effects of elevated CO2 than elevated O3. Root nitrogen content, root carbon to nitrogen ratio, soil microbial biomass carbon and nitrate nitrogen were the main drivers of soil ectoenzyme activities under elevated CO2 and O3. Elevated O3 could partially neutralize the effects of elevated CO2 on soil ectoenzyme activities. In conclusion, elevated CO2 and O3 restrained the activities of most soil ectoenzyme, suggesting that climate change would threat soil ecosystem services and functions in the agroecosystem.
大气二氧化碳(CO2)和臭氧(O3)浓度升高是全球气候变化的主要特征之一。土壤胞外酶作为维持土壤生态系统服务功能的重要参与者,其活性对于大气CO2和O3浓度升高的响应特征及驱动机制研究,以及应对并缓解未来全球气候变化具有重要意义。本研究采用开顶式气室(OTCs)分别模拟大气CO2浓度升高(环境大气+200 μmol·mol-1,eCO2)、大气O3浓度升高(环境大气+0.04 μmol·mol-1,eO3)及其交互处理(环境大气+200 μmol·mol-1 CO2+0.04 μmol·mol-1 O3,eCO2+eO3),探究水稻根际土壤胞外酶活性对大气CO2和O3浓度升高的响应。结果表明:与对照(环境大气)相比,eCO2处理的土壤β-葡萄糖苷酶(βG)活性显著提高73.0%,而多酚氧化酶(PHO)、过氧化物酶(PEO)、酸性磷酸酶(AP)活性分别显著降低48.9%、46.6%和72.9%,纤维素水解酶(CBH)和β-N-乙酰氨基葡萄糖苷酶(NAG)活性则无明显变化;eO3处理的土壤CBH、AP活性分别显著降低34.2%和30.4%;eCO2+eO3处理的土壤PHO、AP活性分别显著降低87.3%和32.3%。主坐标分析、置换多元方差分析和冗余分析显示,大气CO2和O3浓度升高均可显著影响土壤胞外酶活性,且大气CO2浓度升高对土壤胞外酶活性的影响程度高于O3浓度升高;根系氮含量、根系碳氮比、土壤硝态氮和土壤微生物生物量碳是土壤胞外酶活性的主要驱动因子;大气O3浓度升高能够部分中和大气CO2浓度升高对土壤胞外酶活性的影响。综上,大气CO2和O3浓度升高抑制了大部分土壤胞外酶活性,表明未来气候变化潜在威胁着农田土壤生态系统服务功能。.
Keywords: climate change; elevated CO2 concentration; elevated O3 concentration; open-top chamber (OTC).; soil ectoenzyme activity.