高原泥炭地CO2通量对极端干旱的响应机理研究

目的]探明极端干旱事件对高原泥炭地二氧化碳(CO2)通量的影响机制。方法]以若尔盖高原泥炭地为研究对象,采用野外控制实验和静态箱法,利用快速温室气体分析仪测定极端干旱下高原泥炭地CO2通量变化,并结合环境因子及土壤酶活性的测定,分析其变化机制。结果](1)极端干旱显著降低了若尔盖高原泥炭地生态系统的净生态系统CO2交换(NEE)、生态系统呼吸(Re)和总初级生产力(GPP)(P<0.05)。(2)高原泥炭地生态系统Re对于空气温度和土壤温度的相关性在极端干旱的影响下增强。(3)NEE与β-葡萄糖苷酶(BG)、α-葡萄糖苷酶(AG)显著相关(P<0.05),Re与木糖苷酶(XYL)、纤维素外切酶(CB)显著相关(P<0.05),GPP与BG显著相关(P<0.05)。结论]高原泥炭地生态系统CO2通量在极端干旱的影响下将显著降低,其对环境因子的相关性也有所增强;NEE和Re变化分别受到不同土壤酶活性的影响,随着土壤深度的增加,与不同深度土壤温度相关性表现出相反的变化趋势。

Response Mechanism of CO Flux to Extreme Drought on An Plateau Peatland

Objective] To study the mechanism of extreme drought on carbon dioxide(CO2) flux on plateau peatland. Method] The field control experiment and static box method were used to measure the CO2 flux change on Zoige plateau peatland under extreme drought by using the fast greenhouse gas analyzer, and the change mechanism was analyzed combining with the measurement of environmental factors and soil enzyme activity. Result](1) Extreme drought significantly reduced the net ecosystem CO2 exchange(NEE), ecosystem respiration(Re) and gross primary productivity(GPP) of peatland ecosystem on Zoige plateau(P<0.05).(2) The sensitivity of Re to air temperature and soil temperature decreased under the influence of extreme drought.(3) The NEE was significantly correlated with β-glucosidase(BG), α-glucosidase(P<0.05), the Re was significantly correlated with β-xylosidase, β-D-cellobiosidase(P<0.05), and the GPP was significantly correlated with BG(P<0.05). Conclusion] Under extreme drought, the CO2 flux of plateau peatland ecosystem will decrease significantly, and its sensitivity to environmental factors will also be weakened. The changes of NEE and Re are affected by different soil enzyme activities. With the increase of soil depth, the correlation of soil temperature with NEE and Re shows an opposite trend.