不同土地利用方式下土壤呼吸对极端降水脉冲的响应

Response of Soil Respiration to Extreme Precipitation Pulse under Different Land-use Patterns

为研究台风引起的降雨脉冲对土壤呼吸的响应,以2018年8月中旬台风"温比亚"带来的强降雨为契机,选取河南大学金明校区内玉米农田、果树林地和人工草地作为研究对象,利用LI-cor 8100土壤CO2通量全自动测量系统对极端降水后第1天、第7天和第14天土壤呼速率进行检测,并结合土壤温度、含水量、根生物量,分析土壤呼吸脉冲的影响因子。结果表明:①极端降水改变了农田、林地和草地土壤温度和含水量,土壤含水量在不同生态系统间存在显著差异,从大到小依次为农田、草地、林地;②极端降水后各样地呼吸均迅速升高,但草地呼吸升高最明显,可达(14.45±3.19)μmol·m-2·s-1,农田和林地分别为(8.89±2.14)和(8.67±1.80)μmol·m-2·s-1。农田和林地呼吸在1~7 d内脉冲下降明显,15 d后呼吸速率分别为(3.02±0.38)和(2.50±0.84)μmol·m-2·s-1,而草地脉冲效应可以维持7~14 d,15 d后呼吸速率为(2.93±0.57)μmol·m-2·s-1;③土壤呼吸和土壤温度呈指数相关,和土壤含水量呈线性相关。④强降雨之后在1~7 d内的呼吸脉冲不是由植物根系主导的。

To explore the effects of extreme precipitation caused by typhoons on soil respiration(SR)under different land-use patterns,SR was measured using LI-COR 8100 soil CO2 flux automatic measurement system in cropland,plantation forest,and cultivated grassland of Kaifeng,Henan Province in August 2018 after heavy rain induced by typhoon"Wambia".Root biomass and soil temperature and moisture were recorded when SR was measured on the 1 st,the 7 th,and the 14 th days after heavy rain.The results showed that:①Soil moisture was significantly increased in the three different land types,with the highest in the cropland followed by the cultivated grassland and plantation forest.②SR was significantly stimulated by extreme precipitation in this study.SR was up to 14.45±3.19,8.89±2.14,and 8.67±1.80μmol m-2·s-1 in the cultivated grassland,cropland,and plantation forest,respectively.The legacy effect of extreme precipitation on SR lasted for 7 d and then SR dropped to 3.02±0.38 and 2.50±0.84μmol m-2·s-1 in the cropland and plantation forest,respectively,on the 14 th day after extreme precipitation;however,the legacy effect of extreme precipitation on SR in the cultivated grassland maintained for 14 d,and SR returned to 2.93±0.57μmol m-2·s-1 on the 14 th day after extreme precipitation.③SR was exponentially correlated with soil temperature,whereas linearly related to soil moisture.④The enhancement of SR within 1-7 d after extreme precipitation was not mediated by root biomass.