Abstract: A chronic field manipulative experiment of ±30% throughfall (+30%, ?30%, and control, respectively) in a Mongolian pine plantation was carried out to detect the responses of forest soil respiration and its temperature sensitivity to precipitation change at PKU-SOGES, China. Results of repeated measures ANOVA indicate that there is no statistically significant effect of three throughfall treatments on soil respiration rates and apparent Q₁₀ generally (p>0.05). Multiple comparisons of paired t-test show that the soil respiration rates of +30% is statistically higher than that of the control (p<0.001), and the latter is not different from ?30% statistically (p >0.05). The order of apparent temperature sensitivity of soil respiration for three throughfall treatments is ?30% < control < +30% (p >0.05), which has a weak increasing trend along with increased precipitation. The results imply that the impact of chronic precipitation decrease of 30% on forest soil respiration may be rather limited, but the precipitation increase of 30% will stimulate soil CO₂ efflux dramatically.

Key words: soil respiration rate, apparent Q₁₀, precipitation change, manipulative experiment, Saihanba

摘要： 为了研究降水变化对土壤呼吸及其温度敏感性的影响, 在北京大学地球环境与生态系统塞罕坝实验站的樟子松(Pinus sylvestris var. mongolica)人工林中进行了降水控制实验, 用减雨30%、增雨30%和对照3种 穿透雨处理来模拟长期的降水变化情景。重复测量方差分析结果表明, 3种穿透雨处理总体上对生长季土壤 呼吸速率及其表观温度敏感性Q₁₀无显著影响p>0.05)。配对t检验多重比较结果则显示, 土壤呼吸速率平均值大小为对照<减雨30%<增雨30%, 增雨处理的土壤呼吸速率显著高于对照 (p<0.001), 对照和减雨处理之间无显著差异(p>0.05); 土壤呼吸表观Q₁₀平均值大小为减雨30%<对照<增雨30%, 随着降水量增加, 表观Q₁₀逐渐增大, 但处理间差异在统计上并不显著(p>0.05)。研究结果意味着降水量减少30%可能对森林土壤呼吸的限制较小, 而降水量增加30%则可能显著地增加土壤呼吸CO₂释放量。

关键词: 土壤呼吸速率, 表观Q₁₀降水变化, 控制实验, 塞罕坝