Nitrogen (N) and phosphorus (P) limitation constrains the magnitude of terrestrial carbon uptake in response to elevated carbon dioxide and climate change. However, global maps of nutrient limitation are still lacking. Here we examined global N and P limitation using the ratio of site-averaged leaf N and P resorption efficiencies of the dominant species across 171 sites. We evaluated our predictions using a global database of N- and P-limitation experiments based on nutrient additions at 106 and 53 sites, respectively. Globally, we found a shift from relative P to N limitation for both higher latitudes and precipitation seasonality and lower mean annual temperature, temperature seasonality, mean annual precipitation and soil clay fraction. Excluding cropland, urban and glacial areas, we estimate that 18% of the natural terrestrial land area is significantly limited by N, whereas 43% is relatively P limited. The remaining 39% of the natural terrestrial land area could be co-limited by N and P or weakly limited by either nutrient alone. This work provides both a new framework for testing nutrient limitation and a benchmark of N and P limitation for models to constrain predictions of the terrestrial carbon sink.

氮（N）和磷（P）的限制限制了由于二氧化碳含量升高和气候变化而导致的陆地碳吸收量。但是，仍然缺乏全球营养限制图。在这里，我们使用了171个位点上优势种的位点平均叶片N和P吸收效率之比，检查了总体N和P限制。我们分别使用基于N和P限制实验的全球数据库评估了我们的预测，该数据库分别基于在106和53个位置的营养添加量。在全球范围内，我们发现较高纬度和降水季节以及较低的年平均温度，温度季节，年平均降水量和土壤黏土分数均从相对P限制变为N限制。不包括农田，城市和冰川地区，我们估计自然陆地面积的18％受N的限制很大，而43％受P的限制。其余39％的自然陆地面积可能受氮和磷的共同限制，或者仅受任何一种营养素的限制就很少。这项工作既提供了测试养分限制的新框架，又为模型提供了氮和磷限制基准，以约束对陆地碳汇的预测。