作为全球变化的主要成分,温度升高和氮沉降量增多会对土壤呼吸产生深远影响。本研究基于长期增温和氮素添加野外控制试验( 2006年开始处理) ,利用Li-8100开路式碳通量测定系统测定2016年生长季( 5 ~ 10月)土壤呼吸速率,研究土壤呼吸速率对内蒙古短花针茅荒漠草原增温和氮素添加的响应,研究结果表明: 1)氮素添加显著降低了土壤呼吸速率3. 2%( P < 0. 05) ,增温对其没有显著影响( P = 0. 59) ,但是氮素添加与增温共同作用对土壤呼吸速率的影响显著( P < 0. 05) ,在增温条件下,氮素添加使土壤呼吸速率减弱; 2)土壤呼吸速率与土壤湿度呈显著正相关关系( P < 0. 0001) ; 3)土壤呼吸速率对温度的敏感性( Q10值)在增温处理下降低,但是在氮素添加以及氮素添加和增温共同处理下增强。上述结果表明在水分限制的荒漠草原生态系统,氮素添加和增温对土壤呼吸的影响受到水分条件的调控。
英文摘要:
Climate warming and increased nitrogen deposition,as two important components of global changes, can have profound impacts on soil respiration. So we explored the effects of warming and nitrogen fertilization on soil respiration in a Stipa breviflora desert steppe in northern China,based on a long-term warming and nitrogen deposition manipulative experiment initiated since 2006. Soil respiration was monitored by Li-8100 open-circuit carbon flux measurement system-in growing season in 2016( month of May to October) . Three main results emerge: ( 1) Soil respiration rate significantly decreased by 3. 2% with nitrogen fertilization ( P < 0. 05) ,but did not significantly respond to warming ( P = 0. 59) . Significant interaction showed that warming exacerbated the decrease of soil respiration induced by nitrogen fertilization. ( 2) Soil respiration rate was positively correlated with soil moisture ( P < 0. 0001) . ( 3) Sensitivity of soil respiration to temperature ( Q10 value) decreased with warming, but increased with nitrogen fertilization and warming plus nitrogen fertilization. Our results suggest that the effects of warming and nitrogen fertilization on soil respiration could be mediated by water availability in water-limited desert grasslands.