Small-scale spatial patterns of soil organic carbon and nitrogen stocks in permafrost-affected soils of northern Siberia
Small-scale spatial patterns of soil organic carbon and nitrogen stocks in permafrost-affected soils of northern Siberia
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DOI：
10.1016/j.geoderma.2018.05.014
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发表时间：
2018-11-01
期刊：
影响因子：
6.1
通讯作者：
Spielvogel, Sandra
中科院分区：
文献类型：
--
作者：
Evgrafova, Alevtina;de la Haye, Tilman Rene;Spielvogel, Sandra
受多年冻土影响的土壤有机质对气候变化的脆弱性在全球碳(C)循环中起着关键作用。然而，随着冻土层融化深度的变化，土壤和特定地点的因素如何影响高纬度矿物土壤中有机碳(SOC)和总氮(N)储量的空间分布和变异性，目前尚不清楚。土壤有机碳和氮储量(0-30 cm)的空间变异与活动层(AL)厚度、有机层厚度(OL)、土壤酸度、利用普通统计学和地统计学方法研究了西伯利亚森林-冻土带交错带6个景观斑块(16m(2))的Al、Fe氢氧化物以及植物和微生物来源的C输入。在较深的永久冻土区，SOC和N储量(0-30 cm)较低，根据半方差函数分析，在所分析的尺度上，SOC和N的分布总体上是均匀的。土壤全N和土壤有机碳储量在空间上与根源有机质分布无关，而在深层土壤和非冻土中则呈显著的正相关。因此，根系的发育和根深的增加，导致了根际土壤斑块土壤有机质积累的“热点”，这是深层土壤胁迫的结果。深层AL和非冻土底土的全N和SOC储量也与Fe和Al氢氧化物的浓度在空间上呈正相关，表明在冻土表较低的土壤中有机矿物组合对土壤有机质稳定的重要性。这项研究证实，北方森林生态系统AL的加深可能导致SOM分布的整体均质性，并同时发展不同的SOM积累和稳定机制。
The vulnerability of soil organic matter (SOM) sequestered in permafrost-affected soils to climate change plays one of the key roles in the global carbon (C) cycle. However, it still remains unclear how changing soil and site-specific factors, associated with the changing depth of the permafrost table due to thawing, influence the spatial distribution and variability of soil organic carbon (SOC) and total nitrogen (N) stocks in high-latitude mineral soils.The relationships between the spatial variation of SOC and N stocks (0-30 cm) and active layer (AL) thickness, thickness of the organic layer (OL), soil acidity, Al and Fe hydroxides as well as plant- and microbial-derived C inputs were studied using ordinary statistics and geostatistics within six landscape patches (16 m(2) ) in the Siberian forest-tundra ecotone underlain by warm and discontinuous permafrost.At deeper permafrost table, SOC and N stocks (0-30 cm) were lower and, according to the semivariogram analysis, an overall homogenization of SOC and N distribution at the analyzed scale occurred. Total N and SOC stocks were spatially independent from root-derived organic matter distribution (i.e. the concentration of suberin-derived monomers) at shallow AL patches, whereas there was a significant positive spatial correlation within deep AL and non-permafrost soils. Hence, the development of root systems and an increase in rooting depth, leading to "hot spots" of SOM accumulation at intensively rooted soil patches, was observed as a result of deeper AL. Total N and SOC stocks within deeper AL and non-permafrost subsoils were also positively spatially correlated with the concentration of Fe and Al hydroxides, demonstrating the importance of organo-mineral associations for SOM stabilization in soils with lower permafrost table. This study confirmed that deepening of the AL in boreal forest ecosystems may lead to an overall homogenization of SOM distribution and simultaneous development of distinct mechanisms of SOM accumulation and stabilization.