Effects of different types of N deposition on the fungal decomposition activities of temperate forest soils
Effects of different types of N deposition on the fungal decomposition activities of temperate forest soils
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DOI：
10.1016/j.scitotenv.2014.07.098
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发表时间：
2014-11-01
影响因子：
9.8
通讯作者：
He, Jianping
中科院分区：
文献类型：
--
作者：
Li, Shushan;Du, Yuhan;He, Jianping
氮(N)沉降显著影响森林生态系统土壤微生物活性和凋落物分解过程。然而，土壤真菌在凋落物分解过程中的变化仍然不清楚。在本研究中，硝酸铵被选为无机氮(IN)，尿素和甘氨酸被选为有机N(ON)。将不同IN：ON比例(1：4、2：3、3：2、4：1和5：0)的氮肥等量混合后，添加到温带森林土壤中。每个处理的一半同时加入链霉素以抑制土壤细菌。经过三年的田间试验，测定了与凋落物分解有关的酶(转化酶、β-葡萄糖苷酶、纤维素酶、多酚氧化酶和磷酸酶)的活性。结果表明，在非抗生素添加处理中，IN对酶活性有抑制作用，而ON对酶活性有促进作用。混合氮肥中ON的增加也使酶活性从抑制氮转移到促进氮。同样，在抗生素添加处理中，真菌活性也表现出相同的趋势，但它们被IN严重抑制，而被ON显著促进。这些结果表明，土壤真菌对氮素沉降尤其是氮素沉积更为敏感。大量的ON可能会将土壤微生物群落转化为以真菌为主的系统。然而，过量的ON沉积(20%IN+80%ON)会导致N饱和并抑制真菌活性。这些结果表明，土壤真菌对氮素类型敏感，不同的IN/ON比可能对土壤真菌产生不同的生态效应。(C)2014爱思唯尔B.V.保留所有权利。
Nitrogen (N) deposition significantly affects soil microbial activities and litter decomposition processes in forest ecosystems. However, the changes in soil fungi during litter decomposition remain unclear. In this study, ammonium nitrate was selected as inorganic N (IN), whereas urea and glycine were selected as organic N (ON). N fertilizer with different IN-to-ON ratios (1:4, 2:3, 3:2, 4:1, and 5:0) was mixed in equal amounts and then added to temperate forest soils. Half of each treatment was simultaneously added with streptomycin to inhibit soil bacteria. The activities of enzymes involved in litter decomposition (invertase, beta-glucosidase, cellulase, polyphenol oxidase, and phosphatase) were assayed after a three-year field experiment. The results showed that enzymatic activities were inhibited by IN addition but accelerated by ON addition in the non-antibiotic addition treatments. An increase in ON in the mixed N fertilizer also shifted enzymatic activities from N inhibition to N stimulation. Similarly, in the antibiotic addition treatments, fungal activities revealed the same trends, but they were seriously inhibited by IN and significantly accelerated by ON. These results indicated that soil fungi were more sensitive to N deposition, particularly to ON. A large amount of ON may convert soil microbial communities into a fungi-dominated system. However, excessive ON deposition (20% IN + 80% ON) caused N saturation and repressed fungal activities. These results suggested that soil fungi were sensitive to N type and that different IN-to-ON ratios may induce diverse ecological effects on soil fungi. (C) 2014 Elsevier B.V. All rights reserved.