Partitioning of ecosystem respiration in winter wheat and silage maize—modeling seasonal temperature effects
Partitioning of ecosystem respiration in winter wheat and silage maize—modeling seasonal temperature effects
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DOI：
10.1016/j.agee.2016.03.039
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发表时间：
2016-05
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通讯作者：
M. S. Demyan;J. Ingwersen;Yvonne Nkwain Funkuin;Rana Shahbaz Ali;Reza Mirzaeitalarposhti;F. Rasche;C. Pol
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作者：
M. S. Demyan;J. Ingwersen;Yvonne Nkwain Funkuin;Rana Shahbaz Ali;Reza Mirzaeitalarposhti;F. Rasche;C. Pol
需要更好地理解农业生态系统碳(C)呼吸通量对环境变化的响应，因为呼吸亚成分对管理和季节天气动态的响应可能不同，这对于土壤有机质(SOM)模拟是重要的。在两个不同的时空尺度(涡旋协方差(EC)和土室)上进行了呼吸测量，以确定不同生态系统呼吸成分(生态系统(RECO)、土壤和根系结合以及土壤)的温度与CO2通量之间的关系。在此基础上，对不同的模型方法(静态和动态参考CO2速率(Rb)和具有类Arrhenius函数的活化能类型参数(E0))进行了试验，以将恢复划分为地上和地下自养(RA_OPER，RA_DOWER)和异养呼吸(RH_SOM)。在德国西南部的三个生长季节(2009、2010和2012)，利用欧洲电气站和手持小室分析仪测量了冬小麦和青贮玉米的冠层CO2通量和土壤表层CO2通量。此外，在每个生长季节的开始都设置了连续的裸地休耕地块，以区分自养和异养来源的土壤呼吸(包括“不稳定的”土壤C(最新的裸地休耕)，作为与最古老的裸地休耕的区别)。在整个生长期(土室测量的测量周期为15、10或7天)内，通过保持rband E0恒定(静态方法)，然后按时间段(动态方法)单独或一起改变rband E0进行逐步建模试验。动态模型优于Aaike信息标准(AIC)和决定系数(平均R2，静态模型为0.15，动态模型为0.50)。在每个作物年(最低AIC)的最佳拟合模型中，在每个时间段成功地估计了Rb值(相对标准误差为50%)，而在一半的作物年中找到了季节可变的E0估计值。不同成分和季节之间的Q10值估计在1到6.01之间。恢复组分2012年，冬小麦(50%)和玉米(60%)的高强度观测期间，自养的地上呼吸占最大比例，根呼吸分别占19%和21%。此外，在冬小麦下，31%的恢复为异养呼吸，15%来自不稳定的土壤C。结果表明，当使用温度作为生态系统呼吸成分(自养和土壤异养)的驱动力时，需要应用单独的温度响应函数。
The response of agroecosystem carbon (C) respiration fluxes to environmental changes needs to be better understood as respiration subcomponents may respond differently to management and seasonal weather dynamics, which is important for soil organic matter (SOM) modeling. Respiration measurements at two different spatial and temporal scales (eddy covariance (EC) and soil chambers) were used to ascertain the relationship between temperature and CO2flux of different ecosystem respiration components (ecosystem (Reco), soil and root combined, and soil). Further, different model approaches (static versus dynamic reference CO2rate (rb) and activation energy type parameter (E0) with an Arrhenius-like function) in order to partitionRecointo above- and belowground autotrophic (RA_above,RA_below) and heterotrophic respiration (RH_SOM) were tested. Canopy level CO2fluxes in winter wheat and silage maize were measured by EC stations and soil surface CO2flux by a handheld chamber analyzer in arable fields in Southwest Germany over a period of three growing seasons (2009, 2010, and 2012). Additionally, successive bare fallow plots were installed at the beginning of each growing season to partition soil respiration between autotrophic and heterotrophic sources (including “labile” soil C (newest bare fallow) as the difference to the oldest bare fallow). Stepwise model building was tested with keepingrbandE0constant (static method) and then by varyingrbandE0each individually or together by time period (dynamic method) over the whole growing season (15, 10 or 7 days forReco, measurement periods for soil chamber measurements). The dynamic models were superior as measured by Aaike Information Criteria (AIC) and coefficient of determination (averageR2, 0.15 for the static model and 0.50 for the dynamic model). In the best fitting model for each crop-year (lowest AIC),rbwas successfully estimated in each time period (relative standard error <50%), while seasonally variableE0estimates were found in half of the crop years. Estimated Q10values were between 1 to 6.01 between different components and seasons. EstimatedRecocomponents during 2012, autotrophic above ground respiration accounted for the largest component during the intense measurement periods under both winter wheat (50%) and maize (60%), with root respiration accounting for 19% and 21%, respectively. Additionally under winter wheat 31% ofRecowas estimated as heterotrophic respiration, with 15% from labile soil C. The results highlight the need to apply individual temperature response functions when using temperature as a driving force for ecosystem respiration components (autotrophic and soil heterotrophic).