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生物结皮土壤呼吸是干旱区碳循环的重要参与者,是了解荒漠生态系统碳循环的重要过程之一,但有关生物结皮土壤呼吸对水热因子的响应还存在许多不确定性,难以在区域尺度上准确评估生物结皮土壤系统碳排放对水热因子变化的响应及反馈方向和程度。该文以腾格里沙漠东南缘天然植被区藓类和藻-地衣结皮土壤为研究对象,利用开顶式生长室模拟增温,采用全自动土壤碳通量测定系统研究了模拟增温及降水格局变化对不同类型生物结皮土壤呼吸的影响。结果表明:观测期间(2016年4月1日到7月31日),不同自然降水事件下(降水量在0.3–30.0 mm间),藓类结皮土壤呼吸速率在–0.16–4.69μmol·m~(–2)·s~(–1)之间变动,藻-地衣结皮土壤呼吸速率在–0.21–5.72μmol·m~(–2)·s~(–1)之间变动。藓类结皮土壤呼吸速率平均为1.09μmol·m~(–2)·s~(–1),高于藻-地衣结皮土壤呼吸速率的0.94μmol·m~(–2)·s~(–1),是藻-地衣结皮土壤呼吸速率的1.2倍。生物结皮土壤呼吸在不同的降水事件下具有明显的时空异质性,且生物结皮土壤呼吸速率与降水量有显著正相关关系。对照下两类结皮土壤呼吸速率平均为1.24μmol·m~(–2)·s~(–1),增温条件下为0.79μmol·m~(–2)·s~(–1),增温显著降低了其呼吸速率,增温主要是通过加速土壤水分的散失而降低两类结皮土壤呼吸。大多数情况下,土壤温度和生物结皮土壤呼吸呈现类似的单峰曲线,但土壤温度峰值出现的时间滞后于生物结皮土壤呼吸峰值出现的时间,滞后时间一般为2 h。
Soil respiration of biological crusts is an important participant in the carbon cycle in arid regions and one of the important processes in understanding the carbon cycle of desert ecosystems. However, there are still many uncertainties about the response of soil crusts to hydrothermal factors, Accurately assess the response and feedback direction of bio-crust soil system carbon emissions to hydrothermal factors at the regional scale. In this paper, the moss and algal-lichen crust soil in the natural vegetation area of the southeastern margin of the Tengger Desert were studied. The open-top growth chamber was used to simulate warming. The automatic soil carbon flux measurement system was used to study the simulated warming and Effect of precipitation pattern on soil respiration of different types of bio - crusts. The results showed that during the observation period (April 1, 2016 to July 31, 2016), under different natural precipitation events (precipitation between 0.3 and 30.0 mm), soil respiration rate of moss crust ranged from -0.16 to 4.49 μmol · m ~ (-2) · s ~ (-1), and the soil respiration rate of algae-lichen crust varied from -0.21-5.72μmol · m -2 · s -1. The average soil respiration rate of moss crusts was 1.09 μmol · m -2 · s -1, which was higher than 0.94 μmol · m -2 · s ~ (-1) of algae-lichen crust soil respiration rate -1), which is 1.2 times of the soil respiration rate of algae-lichen crust. Soil respiration of the bio-crust had obvious spatio-temporal heterogeneity under different precipitation events, and there was a significant positive correlation between soil respiration rate and precipitation. The average soil respiration rate was 1.24μmol · m -2 · s -1 in the control and 0.79μmol · m -2 · s -1 in the warming condition, Increasing temperature significantly reduced the respiration rate, which was mainly caused by the loss of soil moisture and the reduction of soil respiration in two types of crusts. In most cases, soil temperature and soil crust showed similar unimodal curves, but the peak time of soil temperature lags behind the peak time of soil crust, with a lag time of 2 h.