Divergent effects of elevated CO2, N fertilizattion, and plant diversity on soil C and N dynamics in a grassland field experiment
Divergent effects of elevated CO2, N fertilizattion, and plant diversity on soil C and N dynamics in a grassland field experiment
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DOI：
10.1007/s11104-004-3848-6
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发表时间：
2005-05-01
期刊：
影响因子：
4.9
通讯作者：
Knops, JMH
中科院分区：
文献类型：
--
作者：
Dijkstra, FA;Hobbie, SE;Knops, JMH
虽然大气CO2浓度的增加、氮沉降的增加以及植物多样性的变化都被证明会显著改变土壤碳（C）和氮（N）的动态，但这些因素的影响从未被同时或组合研究过。在美国明尼苏达州的一个草地田间试验中，我们研究了土壤C和N动态对大气CO2（环境，560 ppm）、N施肥（0，4 g N m（-2）yr（-1））、植物种类数（1，4种）和植物功能群数（1，4群;全部4种）变化的响应。在处理的第四个季节，我们使用实验室培养来评估土壤C库的大小和动态以及净氮矿化，并确定微生物C和N以及土壤总C和N。CO2浓度升高增加了土壤活性碳和微生物生物量，但对净氮矿化、更多柠檬酸碳的呼吸或土壤总碳和总氮没有影响。施氮增加净氮矿化，因为更快的分解或固定的凋落物与较高的N浓度。在四个物种的地块，氮肥也增加了土壤总碳和氮，可能是因为更大的凋落物产生超过抵消任何增加分解。增加物种数量从一个到四个增加碳呼吸，这在很大程度上可以归因于更大的土壤碳输入增加生物量积累，但减少净氮矿化，可能是因为更大的固定在更富有成效的四种地块。增加官能团数并不影响任何土壤参数的测量。虽然CO2浓度升高，氮肥，增加物种数增加植物生物量的积累，他们对土壤C和N动态的不同影响。
While increased atmospheric CO2 concentrations, increased N deposition, and changes in plant diversity have all been shown to significantly alter soil carbon (C) and nitrogen (N) dynamics, the effects of these factors have never been studied simultaneously and in combination. We studied the response of soil C and N dynamics to changes in atmospheric CO2 (ambient, 560 ppm), N fertilization (0, 4 g N m(-2) yr(-1)), plant species number (1, 4 species), and plant functional group number (1, 4 groups; all with 4 species) in a grassland field experiment in Minnesota, USA. During the fourth season of treatments, we used laboratory incubations to assess soil C pool sizes and dynamics and net N mineralization, and determined microbial C and N and total soil C and N. Elevated CO2 increased labile C and microbial biomass, but had no effect on net N mineralization, respiration of more recalcitrant C, or total soil C and N. Nitrogen fertilization increased net N mineralization, because of faster decomposition or less immobilization by litter with higher N concentrations. In the four species plots, N fertilization also increased total soil C and N, likely because greater litter production more than offset any increases in decomposition. Increasing the species number from one to four increased C respiration that could largely be attributed to greater soil C inputs from increased biomass accumulation, but reduced net N mineralization, likely because of greater immobilization in the more productive four-species plots. An increase in functional group number did not affect any of the soil parameters measured. While elevated CO2, N fertilization, and increased species number all increased plant biomass accumulation, they had divergent effects on soil C and N dynamics.