Yang Cheng-Bang, Zhang Li, Gao Yan-Li, Wu Na, Chen Shi-Dong, Liu Xiao-Fei, Yang Zhi-Jie
College of Geographical Sciences, Fujian Normal University/Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology, Fuzhou 350007, China.
Sanming Forest Ecosystem and Global Change Observation and Research Station of Fujian Province, Sanming 365000, Fujian, China.
Ying Yong Sheng Tai Xue Bao. 2020 Sep 15;31(9):2849-2856. doi: 10.13287/j.1001-9332.202009.001.
Soil nitrogen cycling in forests may be accelerated or inhibited by global warming, with consequences on forest productivity. Such an impact will be more complicated with extending period of warming. We examined the effects of warming on soil inorganic nitrogen content in the young and mature plantations. Warming was simulated by means of soil cable warming, simulating a future climate change scenario of 4 ℃ warming. The results showed that after three years warming, both total soil inorganic nitrogen and ammonium contents in the young and mature plantations were significantly reduced. The sharp decline occurred in the young plantation, with soil ammonium content in 0-10, 10-20, 20-40, 40-60 cm soil layers decreased by 32.1%, 37.1%, 20.8% and 19.9%, respectively. Dissolved organic nitrogen was reduced and NO emission was accelerated in the both plantations. The main reasons for the reduction of soil inorganic nitrogen concentration were lower input of organic nitrogen substrate and higher gaseous nitrogen loss. The decrease in soil organic nitrogen substrate and increase in gaseous nitrogen emissions in the young plantation were larger than those in the mature plantation, indicating that soils in the young plantation were more sensitive to increasing temperature. The 3-year warming decreased soil inorganic nitrogen contents in the two plantations, which might negatively affect productivity of the plantations in subtropic China.
森林中的土壤氮循环可能会因全球变暖而加速或受到抑制，进而影响森林生产力。随着变暖时间的延长，这种影响会更加复杂。我们研究了变暖对幼龄和成熟人工林土壤无机氮含量的影响。通过土壤电缆加热模拟变暖，模拟未来升温4℃的气候变化情景。结果表明，经过三年的变暖处理，幼龄和成熟人工林中土壤无机氮总量和铵含量均显著降低。幼龄人工林下降幅度较大，0-10厘米、10-20厘米、20-40厘米、40-60厘米土层的土壤铵含量分别下降了32.1%、37.1%、20.8%和19.9%。两个林分中溶解有机氮减少，NO排放加速。土壤无机氮浓度降低的主要原因是有机氮底物输入减少和气态氮损失增加。幼龄人工林中土壤有机氮底物的减少和气态氮排放的增加幅度大于成熟人工林，表明幼龄人工林土壤对温度升高更为敏感。三年的变暖降低了两个林分的土壤无机氮含量，这可能会对中国亚热带人工林的生产力产生负面影响。
