亚高山红桦根及根际土壤生化特性对升高温度和CO_2的响应

Responses of Soil Biological Properties of Betula Roots and Rhizosphere to Short-Term Temperature and CO_2 Elevation in the Subalpine Zone

通过川西亚高山野外大型控制实验,研究了红桦不同密度下的根系生物量、根际土壤微生物数量和根际土壤酶活性对短期升高温度(ET,相对室外平均升温2.4±0.4℃)、升高大气CO2浓度(EC,平均增加15.5±1.0μmol.L-1)及交互作用(ETC,生长室相对室外平均升温2.2±0.5℃并CO2浓度平均增加15.8±1.2μmol.L-1)的响应.初步结果表明:升高大气温度或CO2浓度均能够显著促进红桦低密度和高密度下单株根系生物量;升高温度和CO2浓度及二者共同升高对微生物类群和数量影响不同,升高温度细菌、真菌数量以及低密度下放线菌数量显著增加,而高密度下放线菌数量显著下降;升高CO2浓度下高密度时细菌和真菌数量增加而低密度下均显著下降;升高温度(ET)显著抑制高、低密度下红桦根际土壤多酚氧化酶活性,升高CO2(EC)根际土壤过氧化氢酶活性在2种密度条件下均不同程度升高,土壤脲酶和多酚氧化酶活性则降低;ETC条件下,根际土壤多酚氧化酶和过氧化氢酶在2种密度下均表现出不同程度的降低,但脲酶活性在高、低密度条件下对ETC表现出不同的响应结果.

Responses of root biomass, microbe quantities, and enzyme activities in rhizospheric soil of Betula albo-sinensis with high and low densities （13.5 stems·m^-2 and 4.5 stems·m^-2, respectively） to elevated atmospheric CO2 concentration （ 15.5 ± 1.0 μmol·L^-1 enrichment） and/or temperature （2.4 ± 0.4 ℃ elevation） under the controlled conditions in situ which have been monitored in the subalpine forest zone of the western Sichuan Province. The primary resuits indicated that root biomass increased when atmospheric temperature and/or CO2 was elevated under the high and low density. The quantities of bacteria and epiphyte under high and low density, and actinomycetes under low density treatments were promoted by temperature elevation, while quantities of bacteria and epiphytes increased just under high density when CO2 was elevated. Pohyphenol oxidase activity was reduced significantly under temperature elevation in both density treatments. Catalase activity increased under CO2 elevation, whereas urease and pohyphenol oxidase decreased in both density treatments. Pohyphenol oxidase and catalase activities decreased under temperature and CO2 elevation （ETC） in high and low density treatments, while urease activities varied with plant density under both temperature and CO2 elevation （ETC）.