Comparing microbial and chemical kinetics for modelling soil organic carbon decomposition using the DecoChem v1.0 and DecoBio v1.0 models
Comparing microbial and chemical kinetics for modelling soil organic carbon decomposition using the DecoChem v1.0 and DecoBio v1.0 models
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DOI：
10.5194/gmd-7-1519-2014
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发表时间：
2014-07
影响因子：
5.1
通讯作者：
G. Xenakis;M. Williams
中科院分区：
文献类型：
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作者：
G. Xenakis;M. Williams
抽象的。土壤有机质是一种巨大的碳储存，在全球碳循环中发挥着关键作用。尽管它的重要性，土壤有机碳分解的动态，气候变化的影响下，或不断变化的凋落物投入，知之甚少。目前的生物地球化学模型通常缺乏微生物过程，因此在考虑碳的命运时错过了一个重要的反馈。在这里，我们使用了一系列的建模实验来评估两种不同的模型结构：一个是标准的一阶动力学表示的土壤分解（DecoChem v1.0，以下化学模型）和一个控制土壤分解通过微生物活性（DecoBio v1.0，以下生物模型）。生物模型包括有机物质进入和离开微生物生物量的循环，并模拟作为微生物活性函数的衰减率。我们测试了两个假设。首先，我们假设两种模型对增加窝输入和葡萄糖添加的反应不同。在微生物模型中，我们假设这种扰动会引发微生物活动并减少土壤碳储量;在化学模型中，我们预计这种扰动会增加碳储量。在生物模型中，对凋落物量变化的反应更快，但随着土壤碳的停留时间改变，土壤碳储备缓冲。然而，在生物模型中，有一个强烈的反应，增加葡萄糖添加（即凋落物质量的变化），随着时间的推移，显着的损失，土壤碳储量，驱动启动。其次，我们假设，变暖将刺激化学模型中的分解和碳的损失，但在生物模型中，由于复杂的微生物反馈，土壤碳对变暖不太敏感。数值实验支持这一假设，与化学模型土壤C停留时间和稳态C股票调整强烈的温度变化，延长了几十年。另一方面，生物模型显示出对温度的快速反应，几年后消退，土壤总碳储量基本不变。微生物模型与实验变暖研究定性一致，发现土壤呼吸的短暂增加在几年内下降。总之，生物模型在很大程度上是缓冲对大规模的变化，凋落物的投入和气候，不像化学模型，而生物模型显示出强大的启动反应，增加不稳定的凋落物。因此，我们的研究结果突出了土壤分解的化学和生物建模方法之间显着不同的敏感性。
Abstract. Soil organic matter is a vast store of carbon, with a critical role in the global carbon cycle. Despite its importance, the dynamics of soil organic carbon decomposition, under the impact of climate change or changing litter inputs, are poorly understood. Current biogeochemical models usually lack microbial processes and thus miss an important feedback when considering the fate of carbon. Here we use a series of modelling experiments to evaluate two different model structures: one with a standard first-order kinetic representation of soil decomposition (DecoChem v1.0, hereafter chemical model) and one with control of soil decomposition through microbial activity (DecoBio v1.0, hereafter biological model). The biological model includes cycling of organic matter into and out of microbial biomass, and simulates the decay rate as a functional of microbial activity. We tested two hypotheses. First, we hypothesized different responses in the two models to increased litter inputs and glucose additions. In the microbial model we hypothesized that this perturbation would prime microbial activity and reduce soil carbon stocks; in the chemical model we expected this perturbation to increase C stocks. In the biological model, responses to changed litter quantity were more rapid, but with the residence time of soil C altering such that soil C stocks were buffered. However, in the biological model there was a strong response to increased glucose additions (i.e. changes in litter quality), with significant losses to soil C stocks over time, driven by priming. Secondly, we hypothesized that warming will stimulate decomposition in the chemical model and loss of C, but in the biological model soil C will be less sensitive to warming, due to complex microbial feedbacks. The numerical experiments supported this hypothesis, with the chemical model soil C residence times and steady-state C stocks adjusting strongly with temperature changes, extending over decades. On the other hand, the biological model showed a rapid response to temperature that subsided after a few years, with total soil C stocks largely unchanged. The microbial model shows qualitative agreement with experimental warming studies that found transient increases in soil respiration that decline within a few years. In conclusion, the biological model is largely buffered against bulk changes in litter inputs and climate, unlike the chemical model, while the biological model displays a strong priming response to additions of labile litter. Our results have therefore highlighted significantly different sensitivities between chemical and biological modelling approaches for soil decomposition.