短期增温对内蒙古大青山油松人工林土壤净氮矿化速率的影响

Effects of Short-term Warming on Soil Nitrogen Mineralization Rate of Pinus tabulaeformis Plantation in Daqingshan,Inner Mongolia

利用顶盖埋管法,研究短期模拟增温(1年)对大青山油松人工林(Pinus tabuliformis)土壤的铵化、硝化及氮矿化速率的影响。结果表明:模拟增温显著提高了各层土壤温度,其中5、10、20、40 cm土层土壤温度分别增加了1.09、1.37、1.14、1.44℃,5、10、20 cm土层土壤湿度分别较CK减少了3.63%、1.91%、6.71%,40 cm土层增加1.20%。增温处理下0~10 cm土层土壤碱解氮和全氮含量较CK分别增加了54.02%和40.91%,10~20 cm土层土壤的全氮、有机碳含量分别增加了40.00%、41.26%。增温处理下土壤净氮矿化速率呈现季节单峰曲线变化趋势,8月达到峰值。模拟增温使0~10 cm土层土壤的铵化速率和硝化速率分别降低了19%、200%,10~20 cm土层降低了6%、17%,表层和下层土壤的净氮矿化速率分别降低了52%和51%。增温处理下,随着土壤深度的增加,土壤湿度降低,这是导致土壤净氮矿化速率降低的主要原因。

In this paper,the effects of short-term simulated warming(one year)on the rates of soil ammonification,nitrification and nitrogen mineralization of Pinus tabulaeformis plantation in Daqingshan were studied.The results showed that the simulated warming significantly increased the soil temperature in each layer,in which the soil temperature in 5 cm,10 cm,20 cm and 40 cm increased by 1.09,1.37,1.14 and 1.44℃respectively.The soil moisture of 5 cm,10 cm and 20 cm soil layers decreased by 3.63%,1.91%and 6.71%respectively compared with the control,and the soil moisture of 40 cm soil layers increased by 1.20%.Under warming treatment,the contents of alkali hydrolyzable nitrogen and total nitrogen in 0-10 cm soil of Pinus tabulaeformis plantation increased by 54.02%and 40.91%respectively compared with the control,and the contents of total nitrogen and organic carbon in 10-20 cm soil increased by 40.00%and 41.26%respectively.Under warming treatment,the mineralization rate of soil net nitrogen showed a seasonal single peak curve,and reached the peak in August.The simulated warming reduced the ammonification rate and nitrification rate of 0-10 cm soil layer by 19%and 200%,6%and 17%in 10-20 cm soil layer,and the net nitrogen mineralization rate of surface and lower soil layer by 52%and 51%respectively.Under the warming treatment,with the increase of soil depth,the soil humidity decreases.The decrease of soil humidity is the main reason for the decrease of soil net nitrogen mineralization rate.