| 摘要: |
| 土壤呼吸是区域碳收支及全球变化的热点问题之一，植物作为碳循环重要的生物库对土壤呼吸有着深远的影响。本文以黄河三角洲柽柳灌丛周边土壤的CO2通量变化的时空特征为研究目的，采用LI-8100A开路式土壤碳通量监测系统，分析了不同生境条件下柽柳对周边的土壤呼吸的影响，结果表明：（1）研究区生境可分为低盐-高养与高盐-低养。低盐生境中的柽柳灌丛，其周边土壤的土壤呼吸速率明显高于高盐生境，夏秋两季的日动态没有明显的“单峰曲线”特征，春季峰值具有明显的“滞后”现象。（2）柽柳灌丛的南（S）、北（N）方向上，S方向更容易获得光照与热量，表现为春秋两季S方向的土壤呼吸速率高于N方向，但夏季这种现象却恰好相反。土壤呼吸速率昼夜差异较大，但夜间土壤呼吸速率却不容忽视，接近总量的40%，春季土壤呼吸速率昼夜差异最大。（3）以柽柳灌丛中心为起点由近及远，呈现出随着距离的增加土壤呼吸速率逐渐降低的趋势，这种趋势在低盐生境的灌丛周边尤为明显。高盐生境中，S方向的土壤呼吸速率为远距柽柳处的较高，这种“逆反”现象与温度、湿度交替的较大变异有一定关系。 |
| 关键词: 黄河三角洲 滨海湿地 柽柳灌丛 土壤呼吸 |
| DOI：10.7515/JEE222015 |
| CSTR： |
| 分类号: |
| 基金项目:国家自然科学基金项目（40901276）；聊城大学基金项目（321021916） |
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| Effects of Tamarix chinensis shrub on soil respiration in the Yellow River Delta |
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MA Xiaodan, LIU Jiazhen, CHEN Yongjin, MA Rongzhen, XU Mengchen
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1. School of Geography and Environment, Liaocheng University, Liaocheng 252059, China
2. The Sixth Engineering Company of Shandong High Speed Engineering Construction Group Co., Ltd., Jinan 250101, China
3. Jinan Environmental Research Academy, Jinan 250101, China
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| Abstract: |
| Background, aim, and scope Soil respiration is one of the hot issues around regional carbon budget and global climate change, and plants play crucial role in soil CO2 flux. As one of the biological reservoirs of carbon cycle, plants can influence soil respiration by influencing surrounding temperature and humidity. In Tamarix chinensis, with the characteristics of fertilizing soil and salt tolerance, is the dominant species of woody plants in the Yellow River Delt. It can not only promote the soil nutrients to accumulate around the shrub, but also improve the soil texture. In the view of carbon fixation, Tamarix chinensis plays an active role in the regional carbon cycle, reducing CO2 emission. This paper aims to make clear the temporal and spatial characteristics of soil CO2 flux around Tamarix chinensis shrub in the wetland of the Yellow River Delta, and the effects of Tamarix chinensis on soil respiration in different habitats. Materials and methods In April, July and October 2015, the Open Circuit Soil Carbon Flux Measurement System (LI-8100A) was selected for data monitoring on sunny days. The monitoring points were arranged in the north and south direction of the shrub, with 6 monitoring points respectively. Soil temperature and moisture were measured synchronously at each monitoring point including the atmospheric temperature and humidity at 5—10 cm above the ground surface, the soil humidity and the soil temperature at 0—5 cm layer of the soil profile. The 0—10 cm soil samples were collected in the N and S directions to determine the content of soil organic matter and the soil total salt. Data calculation were completed in Excel 2007 and SPSS 17.0. Results The results show that: (1) the habitats where Tamarix chinensis grow were characterized with low salt-high nutrient and high salt-low nutrient. In low salt habitat, the soil respiration rate around Tamarix chinensis shrub was significantly higher than that of high salt habitat, daily dynamics of soil respiration rate in summer and autumn were no obvious “single peak curve” characteristic, and the peak value of soil respiration rate in spring had an obvious “lag” phenomenon. (2) Soil respiration rate of south (S) direction of Tamarix chinensis was higher than that of north (N) direction in spring and autumn, this phenomena may be attributed to the soil in S direction of Tamarix chinensis being easier to obtain the light and heat than that of N direction. However, the soil respiration rate reversed of the two directions in summer, which tells us that too high temperature was adverse to soil respiration. The soil respiration rate at night, with close to 40% of the total in summer, should not be ignored. The biggest difference of soil respiration rate between day and night occurred in spring. (3) The soil respiration rate gradually decreased with the increase of the spatial distance to Tamarix chinensis, this characteristic was particularly obvious around the shrub in low salt habitat. In the habitat of high salinity, the south soil respiration rate at the sites farther away from Tamarix chinensis was higher than that near the Tamarix chinensis. This “reverse” phenomenon was related to the great fluctuation of temperature and humidity. Discussion (1) The diurnal variation of soil respiration rate mostly showed a unimodal curve, and the highest value appeared at 12∶00—14∶00 at noon. In this paper, the diurnal variation of soil respiration in the two habitats also showed a single peak curve. However, the peak appeared at 10∶00—16∶00 in this study, either high-salinity and low-nutrient environment or low-salinity and high-nutrient environment. Especially at the site of 50 cm away from the center of the shrub in the low-salt and high-nutrient environment, there was no obvious peak of the soil respiration rate. Here, the change of soil respiration rate under the influence of Tamarix chinensis shrub was not sensitive. (2) Some studies have shown that dry and wet fluctuations could cause the excitation effect of soil respiration. The variation coefficient of soil temperature and humidity at the sites of 250 cm away from Tamarix chinensis shrub in the south direction fluctuated greatly, especially the variation of soil temperature. Therefore, the soil respiration value at 250 cm in south direction was higher than that at 300 cm in summer. On the other hand, the wind blew the plants litters to gather the lowland, thereby promoting the activities of microorganisms and making the soil respiration rate larger. Conclusions The Tamarix chinensis shrub can affect the heterogeneity of its surrounding environment and lead to the spatial heterogeneity of soil respiration. The influence is obvious in the ranges of 100 cm from Tamarix chinensis. Recommendations and perspectives The temporal and spatial changes of soil respiration surrounding the Tamarix chinensis in the Yellow River Delta will provide the theoretical reference for achieving carbon peaks and carbon neutrality goals and offer a scientific basis for protecting the wetlands of the Yellow River Delta. |
| Key words: Yellow River Delta coastal wetland shrub of Tamarix chinensis soil respiration |
