石羊河下游白刺灌丛演替发育过程的土壤呼吸及其影响因素分析

Soil Respiration of Nitraria tangutorum Nebkhas at Different Evolvement Stages in Lower Reaches of Shiyang River and Its Influencing Factors

对不同类型土壤呼吸及其影响因素的研究有助于了解区域生态过程和全球气候变化。在石羊河下游,根据白刺灌丛生长及其生境状况,选择了初期发育、稳定、衰退、严重衰退的白刺灌丛植被,采用Li-8100土壤碳通量监测系统,研究了白刺灌丛演替过程的土壤呼吸日变化。结果表明,各发育阶段的白刺灌丛土壤呼吸最大值均出现在12:00,呼吸速率均值大小顺序为:稳定阶段>初期发育阶段>衰退阶段>严重衰退阶段。各发育阶段不同坡位土壤呼吸日变化动态存在差异,但平均值都表现为迎风坡>背风坡>丘间地。建立各因素与土壤呼吸之间的模型发现,白刺的生长状况与土壤呼吸之间的相关性达到极显著,表层土壤含水量对土壤呼吸的影响大于深层土壤,而二次函数较其他模型能更好地表达地下10cm温度与土壤呼吸之间的关系,且两者之间相关性达到极显著。

Study of soil respiration in different environment and its influencing factors is helpful to understand regional ecological process and global climate change.Soil respiration of Nitraria tangutorum nebkhas at different evolvement stages at lower reaches of Shiyang River,early development stage,stable stage,declension stage and severe declension stage,was studied through observation with LI-8100 automated soil CO2 flux system.Results showed that the maximum values of soil respiration appeared at 12：00 for Nitraria tangutorum nebkhas at all sites in different evolvement stages,and the mean values of soil respiration rate are ranked as： stable stage＇searly development stage＇sdeclension stage＇ssevere declension stage＇s.The diurnal variation of soil respiration at different slope position at different evolvement stages was different,but the average values were in order of windward slope＇sleeward slope＇sinter-dune＇s.Modeling of soil respiration and its influencing factors showed that correlation between soil respiration and growth condition of Nitraria tangutorum was extremely significant and the surface soil moisture had greater influence on the soil respiration than deep soil.Quadratic function could better fit the relationship between the soil temperature at 10-cm depth and soil respiration than other models and the correlation was extremely significant.