作 者 ：江长胜,郝庆菊*,宋长春,胡必琴
期 刊 ：生态学报 2010年 30卷 17期 页码：4539~4548
Keywords:marsh, reclamation, farmland, soil respiration,
摘 要 ：三江平原是我国最大的沼泽化低平原，同时也是受人类活动影响最剧烈的区域之一。选取三江平原两类典型湿地-常年积水的毛果苔草（Carex lasiocapa）沼泽和季节性积水的小叶章（Deyeuxia angustifolia）草甸及由其垦殖的水田和旱田为研究对象，利用静态暗箱-气相色谱法对土壤呼吸速率进行了观测。研究结果表明，小叶章草甸与毛果苔草沼泽土壤呼吸速率的季节变化形式相同，为单峰型，在夏季出现排放峰值，而冬季呼吸速率最低。沼泽湿地垦殖为旱田后，土壤呼吸速率的季节变化形式未发生变化，但垦殖为水田后，土壤呼吸速率排放峰值的时间延后在秋季出现。毛果苔草沼泽、小叶章草甸、旱田及水田通过土壤呼吸释放的碳量分别为(3.1±0.4)、(4.8±0.7)、(2.8±0.4)\,(2.2±0.3) tC?hm-2?a-1。毛果苔草沼泽土壤呼吸速率低于小叶章草甸是由沼泽湿地的积水环境差异造成的，而沼泽湿地垦殖为农田后土壤呼吸作用减弱，主要是由于垦殖后土壤有机碳含量大幅降低所致。相关分析表明，温度和土壤湿度（或积水深度）是影响土壤呼吸速率的重要因素，温度与小叶章草甸、毛果苔草沼泽以及旱田土壤呼吸速率呈显著指数关系，Q10值分别为2.1、2.5和1.8，沼泽湿地垦殖为旱田后温度敏感性指数降低，主要是由于土壤微生物营养源减少从而对微生物营养供应受限造成的。小叶章草甸、毛果苔草沼泽、旱田以及水田土壤呼吸速率与土壤湿度/积水深度之间的关系可用线性或二次曲线方程来描述。
Abstract:The Sanjiang Plain is the largest low-altitudinal swampy plain in China where has been strongly affected by human activities particularly the conversion of marsh to cropland. To evaluate the effect of marsh reclamation on soil respiration, field observations were made at the Sanjiang Mire Wetland Experimental Station (47°35′N, 133°31′E), Chinese Academy of Sciences, located in the eastern part of Heilongjiang Province. Four plots of Carex lasiocarpa marsh, Deyeuxia angustifolia marsh, rice field and dryland were selected in this study. During the experimental periods, measurements were made twice a week in growing season and once a month in the winter. Three replicates were conducted for each plot. Soil respiration rate was measured using the static opaque chamber and gas chromatography system. Results showed that the seasonal changes of soil respiration rates from Carex lasiocarpa marsh and Deyeuxia angustifolia marsh were identical with single-peak. The largest values appeared in summer and the lowest ones appeared in winter. The seasonal variation of soil respiration rate from dryland was the same as the marshland, but the seasonal course of soil respiration rate from rice field changed and the peak values postponed in autumn. The carbon effluxes by soil respiration from Carex lasiocarpa marsh, Deyeuxia angustifolia marsh, dryland and rice field were (3.14±0.45),(4.81±0.68),(2.85±038), (2.18±0.31) tC?hm-2?a-1, respectively. The difference in soil respiration rates between Carex lasiocarpa marsh and Deyeuxia angustifolia marsh was caused by water environment. The lower soil respiration rates from farmland than from marshland was induced by reduced soil organic carbon contents due to marsh reclamation. Temperature and soil moisture/water table were important factors controlling soil respiration. Significant relationships were found between temperature and soil respiration rate from Carex lasiocarpa marsh, Deyeuxia angustifolia marsh and dryland, which could be best described by the exponential equations. Q10 values were 2.1, 2.5 and 1.8, respectively for Carex lasiocarpa marsh, Deyeuxia angustifolia marsh and dryland, and tended to decrease in dryland when compared wtih marshland, which was caused by the decrease in substrate sources in soil after marsh reclamation. The relationships between soil respiration rate and soil moisture/water table were best described by linear or quadratic equations.
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