State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, P.O. Box 61, Lanzhou 730000, China.
State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, P.O. Box 61, Lanzhou 730000, China.
Sci Total Environ. 2018 Jun 15;627:1209-1217. doi: 10.1016/j.scitotenv.2018.01.313. Epub 2018 Feb 6.
Using the trenching method, a study was conducted in a grassland on the Loess Plateau of northern China in 2008 and 2009 to partition total soil respiration (Rt) into microbial respiration (Rm) and root respiration (Rr). Using the measurements of soil CO diffusivity and soil CO production, an analytical model was applied to correct the data, aiming to quantify the method-induced error. The results showed that Rm and Rr responded differently to biotic and abiotic factors and exhibited different diurnal and seasonal variations. The diurnal variation of Rm was strongly controlled by soil temperature, while Rr might be mainly controlled by photosynthesis. The combination of soil temperature and moisture could better explain the seasonal variation in Rm (r=0.76, P<0.001). The seasonal variation of Rr was influenced mainly by the plant activity. The contribution of root respiration to total soil respiration (Rr/Rt ratio) also exhibited substantial diurnal and seasonal variations, being higher at nighttime and lower at daytime. In the different growing stages, the Rr/Rt ratios ranged from 15.0% to 62.0% in 2008 and 14.5% to 63.6% in 2009. The mean values of the Rr/Rt ratio in the growing season and the annual mean Rr/Rt ratio were 41.7% and 41.9%, respectively, during the experiment period. Different precipitation distributions in the two years did not change the yearly Rr/Rt ratio. Corrected with the analytical model, the trenching method in small root-free plots led to an underestimation of Rr and Rr/Rt ratio by 4.2% and 1.8%.
2008 年和 2009 年，在中国北方黄土高原的草原上，采用沟垄耕作法，将土壤总呼吸（Rt）分为微生物呼吸（Rm）和根呼吸（Rr）。通过测量土壤 CO 扩散率和土壤 CO 生成量，应用分析模型对数据进行校正，以量化方法诱导的误差。结果表明，Rm 和 Rr 对生物和非生物因素的响应不同，表现出不同的昼夜和季节变化。Rm 的昼夜变化主要受土壤温度控制，而 Rr 可能主要受光合作用控制。土壤温度和水分的组合可以更好地解释 Rm 的季节变化（r=0.76，P<0.001）。Rr 的季节变化主要受植物活动的影响。根呼吸对土壤总呼吸（Rr/Rt 比值）的贡献率也表现出显著的昼夜和季节变化，夜间较高，白天较低。在不同的生长阶段，2008 年 Rr/Rt 比值范围为 15.0%至 62.0%，2009 年为 14.5%至 63.6%。实验期间，生长季的 Rr/Rt 比值平均值和年平均 Rr/Rt 比值分别为 41.7%和 41.9%。两年间不同的降水分布并没有改变年 Rr/Rt 比值。经分析模型校正后，小根免耕小区的沟垄耕作法导致 Rr 和 Rr/Rt 比值低估了 4.2%和 1.8%。
