TRANSIENT NATURE OF CO2 FERTILIZATION IN ARCTIC TUNDRA
TRANSIENT NATURE OF CO2 FERTILIZATION IN ARCTIC TUNDRA
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DOI：
10.1038/371500a0
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发表时间：
1994-10-06
期刊：
影响因子：
64.8
通讯作者：
VOURLITIS, G
中科院分区：
文献类型：
--
作者：
OECHEL, WC;COWLES, S;VOURLITIS, G
关于大气CO2浓度增加对植物净初级生产力（1，3）和净生态系统CO2通量（3-10）的影响，一直存在很多争论。显然相互矛盾的实验结果可能是遗传潜力（11-15）和资源可用性（16-20）的差异，不同的实验条件（21-24）以及许多研究集中在系统的单个组件（2，21，25 -27）而不是整个生态系统的事实的结果。在这里，我们提出了一个完整的原生生态系统的反应，以提高二氧化碳的原位实验的结果。阿拉斯加图里克湖的一片未受干扰的草丛苔原被封闭在温室中，其中CO2水平，湿度和温度可以控制（28），并受到环境（340 p. p.m.）（680 p.p.m.）二氧化碳水平和温度（+4摄氏度）。空气湿度、降水量和土壤地下水位保持在环境控制水平。对于一个加倍的CO2水平，完全稳态的CO2通量重新建立在三个西尔斯，而暴露于更高的温度和加倍的CO2的组合的区域表现出持续的施肥效应，在这段时间内的净生态系统碳固存。这种差异可能是由于较高温度对生长的直接影响（16，29 -33）和矿化增加引起的营养供应增加的间接影响（10，11，19，27，34）而导致的汇活性增强。这些结果表明，本地生态系统对CO2浓度升高的反应可能并不总是积极的，也不太可能是直接的。显然，必须始终在遗传限制、资源可用性和其他此类因素的背景下考虑CO2施肥效应。
THERE has been much debate about the effect of increased atmospheric CO2 concentrations on plant net primary production(1,3) and on net ecosystem CO2 flux(3-10). Apparently conflicting experimental findings could be the result of differences in genetic potential(11-15) and resource availability(16-20), different experimental conditions(21-24) and the fact that many studies have focused on individual components of the system(2,21,25-27) rather than the whole ecosystem. Here we present results of an in situ experiment on the response of an intact native ecosystem to elevated CO2. An undisturbed patch of tussock tundra at Toolik Lake, Alaska, was enclosed in greenhouses in which the CO2 level, moisture and temperature could be controlled(28), and was subjected to ambient (340 p.p.m.) and elevated (680 p.p.m.) levels of CO2 and temperature (+4 degrees C). Air humidity, precipitation and soil water table were maintained at ambient control levels. For a doubled CO2 level alone, complete homeostasis of the CO2 flux was re-established within three Sears, whereas the regions exposed to a combination of higher temperatures and doubled CO2 showed persistent fertilization effect on net ecosystem carbon sequestration over this time. This difference may be due to enhanced sink activity from the direct effects of higher temperatures on growth(16,29-33) and to indirect effects from enhanced nutrient supply caused by increased mineralization(10,11,19,27,34). These results indicate that the responses of native ecosystems to elevated CO2 may not always be positive, and are unlikely to be straightforward. Clearly, CO2 fertilization effects must always be considered in the context of genetic limitation, resource availability and other such factors.