长期增温对土壤酶活性的影响

The Influence of Long-term Warming on Soil Enzyme Activities

  • 摘要: 全球变暖是影响土壤碳氮循环过程的关键环境因子, 其影响效应因土壤类型不同而存在差异, 但土壤胞外酶调控机制尚不清楚。为研究土壤胞外酶活性对长期增温的响应, 本研究选择红壤、砖红壤、黑土、棕壤、紫色土和黄土6种常见土壤为研究对象, 利用开放式增温系统(FATI)对冬小麦全生育期进行全天增温模拟试验。测定土壤蔗糖酶(SC)、纤维二糖水解酶(CBH)、β-葡萄糖苷酶(βG)、β-木糖苷酶(βX)、脲酶(UE)、β-乙酰氨基葡萄糖苷酶(NAG)、磷酸酶(AP)和过氧化氢酶(CAT)的活性。结果表明: 增温(+2 ℃)处理显著增强了土壤酶活性, 且不同酶类在不同土壤类型中的响应特征存在极显著差异(P < 0.01)。黑土中蔗糖酶活性表现出最强的温度敏感性, 其活性增幅达104.7%, 显著高于其他土壤类型(P < 0.01);黄土脲酶活性对增温的响应最为显著, 其活性提升了79.22%, 显著高于常温对照处理(P < 0.01)。不同土壤类型中碳循环酶、氮循环酶和磷循环酶活性存在显著差异(P < 0.01), 增温提高了红壤的碳循环酶和氮循环酶活性, 降低了紫色土的氮循环酶和磷循环酶活性。在碳循环酶中, 碱性土壤的βX和过氧化氢酶活性显著高于其他土壤类型(P < 0.01)。在氮循环酶中, 酸性土壤的脲酶活性显著高于其他土壤类型(P < 0.01)。在磷循环酶中, 中性土壤的碱性磷酸酶活性显著高于其他土壤类型(P < 0.01)。无论是否增温, 6种类型土壤中的微生物均受碳和磷的共同限制。酶化学计量分析发现, 6种类型土壤的酶活性矢量角度均显著大于45°(P < 0.05), 这一现象表明微生物对磷的限制更为敏感。上述结果表明, 增温和土壤类型对土壤碳、氮、磷循环酶活性存在交互作用, 尤其需要加强对磷循环酶的关注。

     

    Abstract: Global warming is a key environmental factor affecting the soil carbon and nitrogen cycle process, and its influence effect varies depending on different soil types. However, the regulatory mechanism of extracellular enzymes in the soil within it remains unclear. To study the response of extracellular enzyme activities in soil to long-term warming, continuous warming simulation experiments were carried out in this study. Six common soil, namely red soil, laterite, black soil, brown soil, purple soil and loess, were selected as the research objects. The Open warming system (FATI) was used to conduct all-day warming of winter wheat throughout its growth period. The activities of soil sucrase (S-SC), cellobiose hydrolase (CBH), β -glucosidase (βG), β -xylitase(βX), urease (S-UE), β -acetylglucosidase (NAG), phosphatase (AP) and catalase (CAT) were determined. The results show that the warming (+2 ℃) treatment significantly enhanced the soil enzyme activities, and there were extremely significant differences in the response characteristics of different enzymes in different soil types (P < 0.01). The sucrase activity in black soil showed the strongest temperature sensitivity, with an increase of 104.7% in its activity, significantly higher than that of other soil types (P < 0.01). The urease activity in loess responded most significantly to temperature increase, with an increase of 79.22% in its activity, significantly higher than that of the normal temperature control treatment (P < 0.01). There were significant differences in carbon cycle enzymes, nitrogen cycle enzymes and phosphorus cycle enzymes among different soil types (P < 0.01). Warming increased the activities of carbon cycle enzymes and nitrogen cycle enzymes in red soil, while reduced the activities of nitrogen cycle enzymes and phosphorus cycle enzymes in purple soil. Among the carbon cycle enzymes, the βX enzyme and catalase in alkaline soil were significantly higher than those in other soil types (P < 0.01). Among nitrogen cycle enzymes, the urease activity in acidic soil was significantly higher than that in other soil types (P < 0.01), and among phosphorus cycle enzymes, the phosphatase activity in neutral soil was significantly higher than that in other soil types (P < 0.01). Whether or not the temperature increases, the microorganisms in the six types of soil are jointly limited by carbon (C) and phosphorus (P). Enzyme stoichiometric analysis reveals that the enzyme activity vector angles of all soil samples were significantly greater than 45° (P < 0.05), which indicates that microorganisms were more sensitive to the limitation of P element. These results indicate that there is an interaction between warming and soil type on the activities of soil carbon, nitrogen and phosphorus cycling enzymes, and particular attention to phosphorus cycling enzymes is needed.

     

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