Minor Changes in Vegetation and Carbon Gas Balance in a Boreal Mire under a Raised CO2 or NH4NO3 Supply
Minor Changes in Vegetation and Carbon Gas Balance in a Boreal Mire under a Raised CO2 or NH4NO3 Supply
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DOI：
10.1007/s10021-002-0208-3
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发表时间：
2003
期刊：
影响因子：
3.7
通讯作者：
S. Saarnio;Sanna Järviö;T. Saarinen;H. Vasander;J. Silvola
中科院分区：
文献类型：
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作者：
S. Saarnio;Sanna Järviö;T. Saarinen;H. Vasander;J. Silvola
大气中二氧化碳（CO2）浓度的增加或氮（N）的持续沉降可能会改变北极沼泽中的碳（C）循环，从而对气候变化的发展产生重大影响。沼泽中碳循环的大气影响是双重的：碳积累减弱和CH 4释放加强自然温室效应。我们研究了增加供应的CO2或NH 4 NO3的植被和每年的CO2交换草坪的北部贫营养沼泽在芬兰东部超过2年的时间内的影响。10块研究地块用mini-FACE（自由空气二氧化碳富集）环封闭。五个试验区用富CO2空气通风（目标值560 ppmv），而其对照组用环境空气通风;五个试验区用NH 4 NO3喷雾，相当于累计添加3 g N m−2a−1，而其对照组仅用蒸馏水喷雾。NH 4 NO3供应量的增加似乎会影响苔藓层的组成。CO2浓度升高不影响植被，但总光合作用显著增加。净CO2交换的变化取决于每年的天气条件。我们的研究结果表明，C的积累可能会增加在潮湿的年份，并弥补了温室效应所造成的增加CH 4释放从这个沼泽。相反，相对干燥和温暖的生长期有利于分解，甚至可以使二氧化碳平衡为负值。沿着CO2浓度升高时CH 4释放量的增加，C积累量的减少则增加了北方沼泽的辐射强迫。
Increasing concentrations of carbon dioxide (CO2) in the atmosphere or continuous nitrogen (N) deposition might alter the carbon (C) cycle in boreal mires and thus have significant impacts on the development of climate change. The atmospheric impact of the C cycle in mires is twofold: C accumulation attenuates and CH4release strengthens the natural greenhouse effect. We studied the effects of an increased supply of CO2or NH4NO3on the vegetation and annual CO2exchange in lawns of a boreal oligotrophic mire in eastern Finland over a 2-year period. Ten study plots were enclosed with mini-FACE (Free Air Carbon Dioxide Enrichment) rings. Five plots were vented with CO2-enriched air (target 560 ppmv), while their controls were vented with ambient air; five plots were sprayed with NH4NO3, corresponding to a cumulative addition of 3 g N m−2a−1, while their controls were sprayed with distilled water only. A raised NH4NO3supply seemed to affect the composition of the moss layer. Raised CO2did not affect the vegetation, but gross photosynthesis increased significantly. The change in net CO2exchange depended on the annual weather conditions. Our results suggest that C accumulation may increase in wet years and compensate for the warming effect caused by the increase in CH4release from this mire. In contrast, a relatively dry and warm growing period favors decomposition and can even make the CO2balance negative. Along with the increased CH4release under raised CO2, the decreased C accumulation then increases the radiative forcing of boreal mires.