Jackson R B, Mooney H A, Schulze E D
Department of Botany, University of Texas at Austin, Austin, TX 78713, USA.
Proc Natl Acad Sci U S A. 1997 Jul 8;94(14):7362-6. doi: 10.1073/pnas.94.14.7362.
Global biogeochemical models have improved dramatically in the last decade in their representation of the biosphere. Although leaf area data are an important input to such models and are readily available globally, global root distributions for modeling water and nutrient uptake and carbon cycling have not been available. This analysis provides global distributions for fine root biomass, length, and surface area with depth in the soil, and global estimates of nutrient pools in fine roots. Calculated root surface area is almost always greater than leaf area, more than an order of magnitude so in grasslands. The average C:N:P ratio in living fine roots is 450:11:1, and global fine root carbon is more than 5% of all carbon contained in the atmosphere. Assuming conservatively that fine roots turn over once per year, they represent 33% of global annual net primary productivity.
在过去十年中，全球生物地球化学模型在对生物圈的表征方面有了显著改进。尽管叶面积数据是此类模型的重要输入，且在全球范围内很容易获取，但用于模拟水分和养分吸收以及碳循环的全球根系分布却并不存在。本分析提供了土壤中细根生物量、长度和表面积随深度的全球分布，以及细根中养分库的全球估计值。计算得出的根表面积几乎总是大于叶面积，在草原上更是超过一个数量级。活细根中的平均碳：氮：磷比率为450：11：1，全球细根碳占大气中所有碳的5%以上。保守估计细根每年周转一次，它们占全球年度净初级生产力的33%。
