外源氮输入下大兴安岭冻土区泥炭地土壤中碳、氮含量和酶的活性

Carbon and Nitrogen Contents and Enzyme Activities of Soil in Peatland of Permafrost Region in Greater Hinggan Mountains under Exogenous Nitrogen Input

选择大兴安岭冻土区典型泥炭地作为实验地,从2012年开始,在连续9 a的5~9月(植物生长季),向实验地中的9块样地输入外源氮,外源氮输入水平分别为6 g/(m^(2)·a)氮、12 g/(m^(2)·a)氮和24 g/(m^(2)·a)氮;2020年8月13日,采集土壤样品,研究外源氮输入下实验地0~20 cm深度和20~40 cm深度土壤中碳、氮含量和酶的活性。研究结果表明,外源氮输入后,实验地0~40 cm深度土壤中的全碳含量无显著变化,0~20 cm深度土壤中的全氮含量显著增大,20~40 cm深度土壤中的全氮含量显著减小,当外源氮输入量为24 g/(m^(2)·a)氮时,0~20 cm深度土壤中的全磷含量显著减小;随着外源氮输入量的增大,0~40 cm深度土壤中的全磷含量逐渐减小;当外源氮输入量为12 g/(m^(2)·a)氮时,20~40 cm深度土壤中的溶解性有机碳含量和0~20 cm深度土壤中微生物量碳含量都显著减小;随着外源氮输入量的增大,0~40 cm深度土壤中溶解性有机氮含量逐渐增大;外源氮输入使0~40 cm深度土壤中微生物量氮含量显著减小;当外源氮输入量为12 g/(m^(2)·a)氮时,0~20 cm深度土壤中蔗糖酶的活性显著增大;当外源氮输入量为24 g/(m^(2)·a)氮时,20~40 cm深度土壤中蔗糖酶的活性显著减小;当外源氮输入量为12 g/(m^(2)·a)氮时,0~40 cm深度土壤中脲酶的活性显著增大;随着外源氮输入量的增大,0~40 cm深度土壤中β-葡萄糖苷酶的活性逐渐减小;外源氮输入对0~40 cm深度土壤中酸性磷酸酶的活性无显著影响。

The typical peatland in permafrost region in Greater Hinggan Mountains was selected as the experimental site.Since 2012,the exogenous nitrogen input of the experimental site has been carried out for 9consecutive growing seasons,with concentrations of 0 g/(m^(2)·a) nitrogen (control site),6 g/(m^(2)·a) nitrogen,12g/(m^(2)·a) nitrogen and 24 g/(m^(2)·a) nitrogen.Soil samples were collected on August 13,2020,to analyze carbon and nitrogen content and enzyme activities of soil at 0-20 cm and 20-40 cm depths in experimental site under the exogenous nitrogen input.The results showed that under exogenous nitrogen input,the total carbon content in soil at 0-40 cm depth didn’t change significantly.But the total nitrogen content in soil at 0-20 cm depth increased significantly,and the total nitrogen content in soil at 20-40 cm depth decreased significantly When the exogenous nitrogen input was 24 g/(m^(2)·a) nitrogen,the total phosphorus content in soil at 0-20 cm depth decreased significantly;with the increase of exogenous nitrogen input,the content of total phosphorus in soil at 0-40 cm depth decreased gradually.When the exogenous nitrogen input was 12 g/(m^(2)·a) nitrogen the content of dissolved organic carbon in soil at 20-40 cm depth and microbial biomass carbon in soil at 0-20cm depth decreased significantly.With the increase of exogenous nitrogen input,the content of dissolved organic nitrogen in soil at 0-40 cm depth gradually increased.Exogenous nitrogen input significantly reduced microbial biomass nitrogen content in soil at 0-40 cm depth.When the exogenous nitrogen input was 12 g/(m^(2)·a)nitrogen,the activity of invertase in soil at 0-20 cm depth increased significantly;when the exogenous nitrogen input was 24 g/(m^(2)·a) nitrogen,the activity of invertase in soil at 20-40 cm depth decreased significantly.When the exogenous nitrogen input was 12 g/(m^(2)·a) nitrogen,the activity of urease in soil at 0-40 cm depth increased significantly.With the increase of exogenous nitrogen input,the activity ofβ-glucosidase in soil at 0-40 cm depth gradually decreased.Exogenous nitrogen input had no significant effect on the activity of acid phosphatase in soil at 0-40 cm depth.