黄河源区建植19年人工草地生物结皮CO_(2)通量与叶绿素荧光参数的变化

Changes of CO_(2) Fluxes and Chlorophyll Fluorescence Parameters of Biological Soil Crusts in a 19-year Artificial Grassland in the Source Zone of the Yellow River

为了解黄河源人工草地不同类型生物结皮和植被群落CO_(2)释放和固定的变化特征,并探讨二者的影响因子,本文通过调查黄河源建植19年人工草地不同类型生物结皮CO_(2)通量和植被土壤特征变化发现:藻和地衣结皮CO_(2)通量均显著小于苔藓结皮(10.58μmol·m^(-2)·s^(-1))(P<0.05);苔藓结皮对应的植被群落CO_(2)通量(11.55μmol·m^(-2)·s^(-1))显著低于藻和地衣结皮(P<0.05);藻和地衣结皮下的土壤CO_(2)通量显著大于苔藓结皮(约2倍,P<0.05)。苔藓结皮叶绿素初始荧光参数F0(Minimal Fluorescence)和最大荧光参数Fm(Maximal Fluorescence)均最大;藻和苔藓结皮的PSⅡ最大光化学量子产量Fv/Fm(Optimal/Maximal Quantum Yield of PSⅡ)均高于地衣结皮。CO_(2)通量和叶绿素荧光参数的主要影响因子相似,均与禾本科高度、土壤铵态氮含量正相关,与pH负相关。因此,在研究草地碳平衡过程中应充分考虑生物结皮的贡献,同时需注意不同类型的生物结皮的CO_(2)通量和叶绿素荧光参数的差异变化。

To understand the variation of CO_(2)release and carbon fixation in different BSCs and vegetation communities in artificial grassland,and to explore the factors influencing CO_(2)release and photosynthesis of BSCs,we measured CO_(2)fluxes and chlorophyll fluorescence parameters of different BSCs in a 19-year-old artificial grassland,vegetation and soil characteristics were also investigated at the same time.The results showed that CO_(2)flux of algal and lichen crusts was significantly lower than that of moss(10.58μmol·m^(-2)·s^(-1))(P<0.05).The CO_(2)flux of the vegetation community was 11.55μmol·m^(-2)·s^(-1) in moss crust stage,which was significantly lower than that in algal and lichen crusts(P<0.05).The CO_(2)flux of the soil covered by algae and lichen crusts was significantly higher than that of moss crusts in soil CO_(2)fluxes test(about 2 times,P<0.05).For chlorophyll fluorescence,the parameters F0 and Fm of moss were the highest.Algal and moss had a higher Fv/Fm than lichen.Redundancy Analysis(RDA)showed that the CO_(2)fluxes and chlorophyll fluorescence were positively correlated with the height of grass and NH+4-N content,but negatively correlated with pH.Thus,it is important to consider the contribution of BSCs to the variability of CO_(2)fluxes and chlorophyll fluorescence in different successional stages.