Reich Peter B, Oleksyn Jacek
Department of Forest Resources, University of Minnesota, St. Paul, 55108-6112, USA.
Proc Natl Acad Sci U S A. 2004 Jul 27;101(30):11001-6. doi: 10.1073/pnas.0403588101. Epub 2004 Jun 22.
A global data set including 5,087 observations of leaf nitrogen (N) and phosphorus (P) for 1,280 plant species at 452 sites and of associated mean climate indices demonstrates broad biogeographic patterns. In general, leaf N and P decline and the N/P ratio increases toward the equator as average temperature and growing season length increase. These patterns are similar for five dominant plant groups, coniferous trees and four angiosperm groups (grasses, herbs, shrubs, and trees). These results support the hypotheses that (i) leaf N and P increase from the tropics to the cooler and drier midlatitudes because of temperature-related plant physiological stoichiometry and biogeographical gradients in soil substrate age and then plateau or decrease at high latitudes because of cold temperature effects on biogeochemistry and (ii) the N/P ratio increases with mean temperature and toward the equator, because P is a major limiting nutrient in older tropical soils and N is the major limiting nutrient in younger temperate and high-latitude soils.
一个全球数据集包含了452个地点1280种植物的5087个叶片氮（N）和磷（P）观测值以及相关的平均气候指数，展示了广泛的生物地理模式。总体而言，随着平均温度和生长季长度增加，叶片N和P含量下降，而N/P比值向赤道方向增加。对于五个主要植物类群，即针叶树和四个被子植物类群（禾本科、草本、灌木和乔木），这些模式是相似的。这些结果支持了以下假设：（i）由于与温度相关的植物生理化学计量以及土壤基质年龄的生物地理梯度，叶片N和P含量从热带地区向凉爽干燥的中纬度地区增加，然后在高纬度地区由于低温对生物地球化学的影响而趋于平稳或下降；（ii）N/P比值随着平均温度升高并向赤道方向增加，因为P是古老热带土壤中的主要限制养分，而N是较年轻的温带和高纬度土壤中的主要限制养分。
