五角槭根系的负激发效应降低了异养呼吸及其温度敏感性

Negative priming effect of maple roots reduced heterotrophic respiration and its temperature sensitivity

土壤呼吸(Rs)由自养呼吸(Ra)和异养呼吸(Rh)组成,这两个组分温度敏感性的差异性存在较大争议,而根际激发效应对R_h呼吸速率及其温度敏感性(Q10)的影响导致这一问题更为复杂化。本研究采用^(13)C自然丰度法,将中国北方温带次生林的重要建群树种C_3植物五角槭种植于曾经连续23年种植玉米的C_4土壤中,以此区分R-a和R_h,并探讨R_a和R_h温度敏感性的差异性以及根际激发效应对R_h呼吸速率和Q_(10)的影响。结果表明:植物根系对R_h呼吸速率有负激发效应,并降低了R_h的温度敏感性;植树土壤的R_h比不植树土壤的无根异养呼吸(Rhf)降低了34.3%,R_h的Q_(10)值(1.51)也显著低于R_(hf)的Q_(10)值(2.07),而Ra的Q_(10)值(3.89)是R_h的Q_(10)值的2.5倍;因此,未来研究在区分R_a和R_h呼吸速率和温度敏感性时,应该考虑根际激发效应对R_h及其温度敏感性的影响,这对于精确评估和模型模拟气候变化背景下R_s的变化和响应具有重要意义。

Soil respiration （Rs） comprises autotrophic （Ra ） and heterotrophic （Rh ） respiration. The difference in temperature sensitivity （Q10） between Ra and Rh is still under debate. Rhizosphere priming effect （RPE） plays an important role in affecting the temperature sensitivity of Ra, which makes the issue more complex. Here we used the 13C natural abundance method by planting Acer mono （C3 plant） in microcosms with maize soil （soil with cultivation of Ca maize for 23 years） to investigate the responses of Ra and Rh to temperature change and the role of RPE. An overall negative RPE was observed in the growing season, which reduced Rh and its Qlo value by 34.3% and 27.0%, respectively. The Q10 value of Ra（3.89） was 2.5 times higher than that of Rh（1.51）. Our results highlight the importance of plant roots in regulating the response of R, to temperature, which should be considered in models of soil respiration in the future.