Different regulatory mechanisms on carbon-degrading enzyme activities under short-term litter input manipulations in subalpine coniferous and broad-leaved forest soils
Xiuxian Men , Yong Bao , Deping Zhai , Chang Liao , Yiyue Wang , Chi Wang , Xiaoli Cheng
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引用次数: 0
Abstract
Soil carbon (C)-degrading extracellular enzyme activities (EEAs) are important regulators in targeting litter and soil organic carbon (SOC) decomposition in territorial ecosystems. However, the responses of enzymes involved in C-cycling to short-term litter input manipulations in different forest ecosystems remain unclear. Here, we examined oxidative C-degrading EEAs (Ox-EEAs), hydrolytic C-degrading EEAs (Hy-EEAs) and their ratios (Ox-to-Hy C EEA ratios) at topsoil (0–10 cm) and subsoil (10–30 cm) after two years of litter manipulations (i.e., Detritus Input and Removal Treatments-DIRT: control, CK; double litter, DL; no roots and double litter, NRDL; no litter, NL; no roots, NR; no roots and no litter, NRNL) in a coniferous forest (Pinus yunnanensis) and a broad-leaved forest (Quercus pannosa) in subalpine area of Southwest China. The litter addition did not significantly affect Ox-EEAs, Hy-EEAs, and their ratios in two forest soils. In contrast, the litter removal significantly decreased Hy-EEAs and slightly affected Ox-EEAs in coniferous forest soil, whereas they increased Ox-EEAs and slightly affected Hy-EEAs in broad-leaved forest soil. Consequently, the Ox-to-Hy C EEA ratios were significantly enhanced by litter removal in both two forest soils. This different variation in Ox-EEAs and Hy-EEAs under litter removal in two forest soils could be attributed to initial soil properties, where soil properties (e.g., pH, total nitrogen [TN], NO3−-N, SOC) with lower C: N ratios in coniferous forest were more likely to promote Hy-EEAs. Whereas microbial parameters (e.g., microbial biomass C) and soil properties (e.g., dissolved organic C) mainly regulated Ox-to-Hy C EEA ratios at topsoil and subsoil in broad-leaved forest, respectively. Overall, our findings revealed different mechanisms and associated drivers on enzymes involved in C-cycling under short-term litter input manipulation of the subalpine coniferous forest and broad-leaved forest soils, which further strengthened our understanding of C-cycling in forest soils.
土壤碳(C)降解胞外酶活性(EEAs)是领土生态系统中针对枯落物和土壤有机碳(SOC)分解的重要调节因子。然而,在不同的森林生态系统中,参与碳循环的酶对短期枯落物输入操纵的反应仍不清楚。在此,我们研究了两年的枯落物处理(即:枯落物输入和清除)后表土(0-10 厘米)和底土(10-30 厘米)上的氧化降解碳的 EEAs(Ox-EEAs)、水解降解碳的 EEAs(Hy-EEAs)及其比率(Ox-Hy C EEAs 比率)、在中国西南亚高山针叶林(云南松)和阔叶林(柞树)中,经过两年的枯落物处理(即:Detritus Input and Removal Treatments-DIRT:对照组,CK;双枯落物处理,DL;无根和双枯落物处理,NRDL;无枯落物处理,NL;无根处理,NR;无根和无枯落物处理,NRNL)后,表土(0-10 cm)和底土(10-30 cm)上的Ox-Hy C EEA比值发生了变化。在两种森林土壤中,添加枯落物对 Ox-EEAs、Hy-EEAs 及其比率没有明显影响。相反,在针叶林土壤中,清除枯落物明显降低了Hy-EEAs,轻微影响了Ox-EEAs;而在阔叶林土壤中,清除枯落物增加了Ox-EEAs,轻微影响了Hy-EEAs。因此,在这两种森林土壤中,Ox-Hy C EEA 比值都因垃圾的清除而显著提高。两种森林土壤在清除枯落物后,Ox-EEAs和Hy-EEAs的不同变化可归因于最初的土壤特性,针叶林中C:N比值较低的土壤特性(如pH值、全氮[TN]、NO3--N、SOC)更有可能促进Hy-EEAs。而在阔叶林中,微生物参数(如微生物生物量C)和土壤性质(如溶解有机C)分别主要调节表土和底土的Ox-Hy C EEA比率。总之,我们的研究结果揭示了亚高山针叶林土壤和阔叶林土壤在短期垃圾输入操纵下参与C循环的酶的不同机制和相关驱动因素,进一步加深了我们对森林土壤C循环的理解。
期刊介绍:
Soil Biology & Biochemistry publishes original research articles of international significance focusing on biological processes in soil and their applications to soil and environmental quality. Major topics include the ecology and biochemical processes of soil organisms, their effects on the environment, and interactions with plants. The journal also welcomes state-of-the-art reviews and discussions on contemporary research in soil biology and biochemistry.