Root and rhizomicrobial respiration: A review of approaches to estimate respiration by autotrophic and heterotrophic organisms in soil
Root and rhizomicrobial respiration: A review of approaches to estimate respiration by autotrophic and heterotrophic organisms in soil
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DOI：
10.1002/jpln.200421703
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发表时间：
2005-08
影响因子：
2.5
通讯作者：
Y. Kuzyakov;A. Larionova
中科院分区：
文献类型：
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作者：
Y. Kuzyakov;A. Larionova
将来自土壤的根源co2外排（通常称为根际呼吸）划分为实际根呼吸（自养生物呼吸RR）和根微生物呼吸（异养生物呼吸RMR）对于确定植物和土壤的碳(C)和能量平衡至关重要。它在量化根际微生物的碳源、估算促进土壤有机质周转（SOM）的碳以及联系净生态系统产量（NEP）和净生态系统交换（NEE）方面也至关重要。人工环境研究，如水培或无菌土壤产生不切实际的C分配值，不适合预测自然条件下的C流动。迄今为止，已经提出了几种方法来分离非无菌土壤中的RR和RMR: 1)组分整合，2)基质诱导的呼吸，3)去除的根的呼吸，4)连续标记后根源性14co 2与根微生物性14co 2的比较，5)同位素稀释，6)模型根沉积技术，7)14co 2外排动力学建模，8)渗出液洗脱，9)CO 2和微生物生物量的δ 13c。本综述描述了这些方法的基本原理和假设，并比较了原始论文和旨在比较这些方法的研究中获得的结果。分量积分法导致不同来源的CO 2外排扰动较大，呈非比例增加。其中四种方法（5至8）是基于在14co2大气中对芽进行脉冲标记以及随后对土壤中14co2流出量的监测。模型-根沉积法和渗出-洗脱法严重高估了相对危险度，而低估了相对危险度。尽管有不同的假设，同位素稀释和14co 2外排动力学模型得出了类似的结果。在作物和禾草（小麦、黑麦草、大麦、荞麦、玉米、草甸羊茅、草原草）中，根源co2的RR平均为48±5%，RMR平均为52±5%。基于co2和微生物生物量的13c同位素特征的方法是最有前途的方法，特别是当植物在13co2或14co2大气中连续标记时。不同的方法，如挖沟法、树环法、排根法等，不适合分离自养和异养生物的呼吸作用，因为不同的方法忽略了根沉积物微生物呼吸作用的重要性。
Partitioning the root-derived CO 2 efflux from soil (frequently termed rhizosphere respiration) into actual root respiration (RR, respiration by autotrophs) and rhizomicrobial respiration (RMR, respiration by heterotrophs) is crucial in determining the carbon (C) and energy balance of plants and soils. it is also essential in quantifying C sources for rhizosphere microorganisms and in estimation of the C contributing to turnover of soil organic matter (SOM), as well as in linking net ecosystem production (NEP) and net ecosystem exchange (NEE). Artificial-environment studies such as hydroponics or sterile soils yield unrealistic C-partitioning values and are unsuitable for predicting C flows under natural conditions. To date, several methods have been suggested to separate RR and RMR in nonsterile soils: 1) component integration, 2) substrate-induced respiration, 3) respiration by excised roots, 4) comparison of root-derived 14 CO 2 with rhizomicrobial 14 CO 2 after continuous labeling, 5) isotope dilution, 6) model-rhizodeposition technique, 7) modeling of 14 CO 2 efflux dynamics, 8) exudate elution, and 9) δ 13 C of CO 2 and microbial biomass. This review describes the basic principles and assumptions of these methods and compares the results obtained in the original papers and in studies designed to compare the methods. The component-integration method leads to strong disturbance and non-proportional increase of CO 2 efflux from different sources. Four of the methods (5 to 8) are based on the pulse labeling of shoots in a 14 CO 2 atmosphere and subsequent monitoring of 14 CO 2 efflux from the soil. The model-rhizodeposition technique and exudate-elution procedure strongly overestimate RR and underestimate RMR. Despite alternative assumptions, isotope dilution and modeling of 14 CO 2 -efflux dynamics yield similar results. In crops and grasses (wheat, ryegrass, barley, buckwheat, maize, meadow fescue, prairie grasses), RR amounts on average to 48±5% and RMR to 52±5% of root-derived CO 2 . The method based on the 13 C isotopic signature of CO 2 and microbial biomass is the most promising approach, especially when the plants are continuously labeled in 13 CO 2 or 14 CO 2 atmosphere. The difference methods, i.e., trenching, tree girdling, root-exclusion techniques, etc., are not suitable for separating the respiration by autotrophic and heterotrophic organisms because the difference methods neglect the importance of microbial respiration of rhizodeposits.