期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 105, 期 49, 页码 19336-19341出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0810021105
关键词
nitrogen cycle; climate change; foliar nitrogen; ecosystem-climate feedback; remote sensing
资金
- NASA
- Harvard Forest
- Hubbard Brook
- Cedar Creek Long-Term Ecological Research programs
- U.S. Department of Agriculture Forest Service Northern Research Station
- Northeastern States Research Cooperative
- U.S. Department of Energy Office of Science (BER) through the Northeastern Regional Center of the National Institute for Climatic Change Research
The availability of nitrogen represents a key constraint on carbon cycling in terrestrial ecosystems, and it is largely in this capacity that the role of N in the Earth's climate system has been considered. Despite this, few studies have included continuous variation in plant N status as a driver of broad-scale carbon cycle analyses. This is partly because of uncertainties in how leaf-level physiological relationships scale to whole ecosystems and because methods for regional to continental detection of plant N concentrations have yet to be developed. Here, we show that ecosystem CO2 uptake capacity in temperate and boreal forests scales directly with whole-canopy N concentrations, mirroring a leaf-level trend that has been observed for woody plants worldwide. We further show that both CO2 uptake capacity and canopy N concentration are strongly and positively correlated with shortwave surface albedo. These results suggest that N plays an additional, and overlooked, role in the climate system via its influence on vegetation reflectivity and shortwave surface energy exchange. We also demonstrate that much of the spatial variation in canopy N can be detected by using broad-band satellite sensors, offering a means through which these findings can be applied toward improved application of coupled carbon cycle-climate models.
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