Responses of soil WEOM quantity and quality to freeze-thaw and litter manipulation with contrasting soil water content: A laboratory experiment
Responses of soil WEOM quantity and quality to freeze-thaw and litter manipulation with contrasting soil water content: A laboratory experiment
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土壤 WEOM 数量和质量对冻融和凋落物处理的响应以及对比土壤含水量：实验室实验
DOI：
10.1016/j.catena.2020.105058
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发表时间：
2021
期刊：
影响因子：
6.2
通讯作者：
Congsheng Fu
中科院分区：
文献类型：
--
作者：
Haohao Wu;Xingkai Xu;Pingqing Fu;Weiguo Cheng;Congsheng Fu
未来气候变化可能会增加高纬度和/或高海拔地区土壤冻融（FT）事件的发生，这可能会显著影响溶解有机质（DOM）释放到土壤中的动态。然而，在不同土壤水分和凋落物处理条件下，北方温带林分土壤DOM的数量和质量对FT格局变化的响应尚不清楚。在这项研究中，凋落物修正和非修正的森林土壤培养360天，在三个土壤水分水平（30%，60%和90%的水填充孔隙空间）和三个强度的FT干扰（低，高，无）。我们量化异养呼吸，酶活性，微生物生物量，和水提取的有机质（WEOM）作为一个代理DOM在土壤中的培养实验。通过生物降解性、紫外吸光度和荧光激发发射矩阵的平行因子分析模型表征了WEOM的质量。在360天的培养期内，所有处理的水提取有机碳（WEOC）和可生物降解的WEOC浓度持续下降。荧光WEOM的主要成分从腐殖酸和富里酸类成分在第一个108天的孵化，蛋白质类成分的微生物来源，其特征在于高芳香性，在孵化期结束。凋落物改良、FT干扰及其相互作用在108天培养期早期增加了土壤中WEOC的浓度，特别是在低水分和高FT强度的土壤中，但在15 °C培养252天后，这些增加消失。在没有FT干扰的土壤中，凋落物衍生的荧光WEOM在孵育14天后主要由蛋白质样组分组成，但在108天后这些被腐殖酸和富里酸样组分所取代。这种替代效应在FT干扰的土壤中较弱，这归因于微生物特性的变化，包括酶活性、微生物生物量和活性。
Future climatic change is likely to increase the occurrence of soil freeze–thaw (FT) events in high latitude and/or high altitude zones, which can substantially influence the dynamics of dissolved organic matter (DOM) released into the soils. However, it is not clear how the quantity and quality of soil DOM respond to changing FT patterns under different soil moisture and litter manipulation conditions in northern temperate forest stands. In this study, litter-amended and non-amended forest soils were incubated for 360 days at three soil moisture levels (30%, 60%, and 90% water-filled pore space) and three intensities of FT disturbance (low, high, and none). We quantified heterotrophic respiration, enzyme activity, microbial biomass, and water-extractable organic matter (WEOM) as a proxy for DOM in soils during the incubation experiment. The quality of WEOM was characterized by biodegradability, UV absorbance and parallel factor analysis modelling of fluorescence excitation emission matrices. Concentrations of water-extractable organic carbon (WEOC) and biodegradable WEOC declined continuously in all treatments over the 360-day incubation period. The dominant component of fluorescent WEOM shifted from humic- and fulvic- like components during the first 108 days of incubation, to protein-like components of microbial origin, characterized by high aromaticity, at the end of the incubation period. Litter amendment, FT disturbance, and their interaction increased WEOC concentrations in soils during the early 108-day incubation period, particularly in soils with low moisture and high FT intensity, but these increases disappeared after 252 days incubation at 15 °C. Litter-derived fluorescent WEOM in soils without FT disturbance was dominated by protein-like components after 14 days of incubation, but these were replaced by humic- and fulvic-like components after 108 days. This replacement effect was weaker in soils with FT disturbance, which we attribute to changes in microbial properties, including enzyme activity, microbial biomass and activity.