Microscale spatiotemporal patterns of water, soil organic carbon, and enzymes in plant litter detritusphere
Microscale spatiotemporal patterns of water, soil organic carbon, and enzymes in plant litter detritusphere
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DOI：
10.1016/j.geoderma.2023.116625
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发表时间：
2023-10
期刊：
影响因子：
6.1
通讯作者：
Kyung-Bum Kim;A. Kaestner;Maik Lucas;A. Kravchenko
中科院分区：
文献类型：
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作者：
Kyung-Bum Kim;A. Kaestner;Maik Lucas;A. Kravchenko
了解腐殖层的生物物理和生化过程对于量化和模拟植物残体分解动力学以及随后的土壤有机碳积累至关重要。本研究的目的是探讨玉米和大豆叶片分解过程中形成的腐质圈内的微环境条件，以及分解过程中水分分布、酶活性和碳动态之间的关系。我们利用x射线和中子计算机断层扫描技术评估了土壤水分分布的时空动态，并利用酶谱法评估了参与土壤C和N处理的β-葡萄糖苷酶和几丁质酶的活性。我们利用13c标记残留物来追踪残留物对大气co2和土壤有机c的贡献，水分的再分配模式因残留物类型而异。玉米叶片会立即吸收水分，并在之后保持水分，而柳枝稷叶片吸收水分的速度较慢，并在距残留物1毫米的范围内形成缺水区。这种初始水分耗竭导致柳枝稷几丁质酶活性和残馀co2排放量降低。与几丁质酶相比，β-葡萄糖苷酶活性受植被历史和残留物类型的共同影响，当残留物来源与土壤植被历史相匹配时，β-葡萄糖苷酶活性较高。孔隙大小对所研究的酶有相反的影响，这支持了不同土壤孔隙结构可以通过选择优势酶产生物来刺激不同酶活性的观点。研究结果表明，植物残茬的分解动力学不仅是残茬化学的简单函数，而且是植被历史的综合作用，部分通过其对微生物群落组成、植物残茬化学特征和可能的物理特征以及碎屑层土壤孔隙结构的影响。它们共同创造了影响分解的时间动态微环境条件。具体来说，我们的研究表明，在腐殖层中形成的初始微环境对酶活性和随后的C动力学起重要作用。
Understanding biophysical and biochemical processes in detritusphere is critical to quantifying and modeling plant residue decomposition dynamics and subsequent soil organic carbon (C) accrual. The objectives of the study were to explore (i) micro-environmental conditions within the detritusphere formed around decomposing corn and soybean leaves, and (ii) the relationships between moisture distribution, enzyme activity, and C dynamics during decomposition. We assessed spatial and temporal dynamics of moisture distribution using X-ray and neutron computed tomography, and activities of β-glucosidase and chitinase, two enzymes involved in soil C and N processing, using zymography. We used13C labeled residue to track residue contribution to atmospheric CO2and soil organic C. Moisture redistribution pattern varied depending on the residue type. While the water was immediately absorbed by the corn leaves and maintained afterward, switchgrass leaves absorbed water more slowly and created water-deficient zones within ∼1mm from the residue. This initial moisture depletion led to lower chitinase activity and residue-derived CO2emissions in switchgrass. In contrast to chitinase, β-glucosidase activity was influenced by a combination of vegetation history and residue type, and it was higher when the origin of the residue matched the vegetation history of the soil. Pore size had an opposite impact on the studied enzymes, supporting the notion that contrasting soil pore architecture can stimulate activities of different enzymes through a selection of dominant enzyme producers. We concluded that the decomposition dynamics of plant residues is not only a simple function of residue chemistry, but rather a combined effect of the vegetation history, in part through its effect on microbial community composition, the plant residue chemical and likely physical characteristics, and the soil pore structure in the detritusphere. Together, they create temporally dynamic micro-environmental conditions influencing decomposition. Specifically, our study demonstrated that the initial micro-environment formulated in detritusphere can play an important role in enzyme activities and consequent C dynamics.