The effects of simulated nitrogen deposition on extracellular enzyme activities of litter and soil among different-aged stands of larch
The effects of simulated nitrogen deposition on extracellular enzyme activities of litter and soil among different-aged stands of larch
复制标题
模拟氮沉降对不同林龄落叶松凋落物和土壤细胞外酶活性的影响
DOI：
10.1093/jpe/rtt028
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发表时间：
2014-06-01
影响因子：
2.7
通讯作者：
Piao, Shilong
中科院分区：
文献类型：
--
作者：
Ma, Yuecun;Zhu, Biao;Piao, Shilong
目的研究施氮量对森林凋落物和土壤有机质分解速率的影响。不同有机质质量的不同年龄林分，施氮对EEA的影响可能不同。我们感兴趣的是，在生长季节的影响，在凋落物和矿质土壤中的EEA添加N是否依赖于在中国北方落叶松种植园的林龄。方法在华北华北落叶松种植园11、20、45年生3个年龄段分别施氮0、20、50 kg N ha-1 a-1。本文测定了施氮后第二次生长海松凋落物（有机层）和矿质土壤（0-10 cm）中β-1，4-葡萄糖苷酶（BG）、纤维二糖水解酶（CB）、β-1，4-N-乙酰氨基葡萄糖苷酶（NAG）和酚氧化酶（PO）的潜在活性。我们还测量了C和N浓度，微生物生物量C和N，KCl提取的铵和硝酸盐在凋落物和矿质土壤。温度林分年龄对凋落物和矿质土壤EEA有很强的影响，这种影响在凋落物和矿质土壤之间以及不同的酶之间存在差异。氮素添加对凋落物BG和CB活性无显著影响，但显著抑制NAG活性。我们还发现，在凋落物和矿质土壤PO活性的年龄特异性的反应，除了N。施氮抑制了20年和45年生高C：N比凋落物的PO活性，对11年生低C：N比凋落物的PO活性影响不显著;施氮抑制了20年生高C：N比土壤的PO活性，对11年和45年生低C：N比土壤的PO活性影响不显著。总体而言，林分年龄有更大的影响EEA在凋落物和矿质土壤相比，2年的N添加。此外，施氮对PO活性的影响是林分年龄依赖性的，这可能会影响该森林的长期土壤碳储量。
Aims Nitrogen (N) addition could affect the rate of forest litter and soil organic matter decomposition by regulating extracellular enzyme activity (EEA). The impact of N addition on EEA may differ across different age stands with different organic matter quality. We were interested in whether the impact of N addition on EEA in litter and mineral soil during the growing season was dependent on stand age of a larch plantation in North China. Methods We added three levels of N (0, 20 and 50 kg N ha −1 year −1 ) in three age stands (11, 20 and 45 years old) of Larix principis-rupprech- tii plantation in North China. We measured potential activities of β-1,4-glucosidase (BG), cellobiohydrolase (CB), β-1,4-N-acetyl- glucosaminidase (NAG) and phenol oxidase (PO) in litter (organic horizon) and mineral soil (0-10 cm) during the second growing sea- son after N amendment. We also measured C and N concentrations, microbial biomass C and N, and KCl-extractable ammonium and nitrate in both litter and mineral soil. temperature. Stand age had a strong effect on EEA in both litter and mineral soil, and this effect differed between litter and mineral soil as well as between different enzymes. N addition did not signifi- cantly affect the activities of BG or CB but significantly suppressed the activity of NAG in litter. We also found stand age-specific responses of PO activity to N addition in both litter and mineral soil. N addition suppressed PO activity of the high C:N ratio litters in 20- and 45-year-old stands but had no significant effect on PO activity of the low C:N ratio litter in 11-year-old stand. Moreover, N addition inhibited PO activity of the high C:N ratio soil in 20-year- old stand but had no significant impact on PO activity of the low C:N ratio soils in 11- and 45-year-old stands. Overall, stand age had a greater effect on EEA in litter and mineral soil compared to 2 years of N addition. Moreover, the effect of N addition on PO activity is stand age dependent, which may affect the long-term soil carbon storage in this forest.