Zhang Yao, Li Ying, Wang Ruomeng, Xu Li, Li Mingxu, Liu Zhaogang, Wu Zhenliang, Zhang Jiahui, Yu Guirui, He Nianpeng
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, China.
Front Plant Sci. 2020 Aug 12;11:1244. doi: 10.3389/fpls.2020.01244. eCollection 2020.
Chlorophyll is the molecular basis for the function of photosystems and is also a promising tool for ecological prediction. However, the large-scale patterns of chlorophyll variation in grasslands remain poorly understood. We performed consistent measurements of chlorophyll , , +, and the : ratio (chlorophyll ) for 421 species across northern hemisphere grassland transects, recorded their distributions, variations, and influencing factors, and examined their relationships with leaf nitrogen. The results showed that the distributional ranges were 0.52-28.33 (mean 5.49) mg·g dry weight, 0.15-12.11 (mean 1.83) mg·g dry weight, 0.67-39.29 (mean 7.32) mg·g dry weight, and 1.28-7.84 (mean 3.02) for chlorophyll , , +, and /, respectively. The chlorophyll averages differed among regions (higher in the Loess Plateau and the Mongolian Plateau than in the Tibetan Plateau), grassland types (desert grasslands > meadow > typical grasslands), life forms, life spans, and taxonomies. In the entire northern hemisphere grassland, chlorophyll concentrations and chlorophyll / were negatively correlated to photosynthetically active radiation and the soil N:P ratio, and positively correlated to the mean annual temperatures. These results implied that chlorophyll in grasslands was shaped by the layered structure of grasses, distinct plateau environments, and phylogeny. The allocation patterns of leaf nitrogen to chlorophyll differed among regions and grassland types, showing that caution is required if simply relating single leaf N or chlorophyll to productivity separately. These findings enhance our understanding of chlorophyll in natural grasslands on a large scale, as well as providing information for ecological predictive models.
叶绿素是光系统功能的分子基础，也是生态预测的一个有前景的工具。然而，草原中叶绿素变化的大规模格局仍知之甚少。我们对北半球草原样带的421个物种的叶绿素a、叶绿素b、叶绿素a+b以及叶绿素a/b比值进行了统一测量，记录了它们的分布、变化及影响因素，并研究了它们与叶片氮含量的关系。结果表明，叶绿素a、叶绿素b、叶绿素a+b以及叶绿素a/b的分布范围分别为0.52 - 28.33（平均5.49）mg·g干重、0.15 - 12.11（平均1.83）mg·g干重、0.67 - 39.29（平均7.32）mg·g干重以及1.28 - 7.84（平均3.02）。叶绿素的平均值在不同区域（黄土高原和蒙古高原高于青藏高原）、草地类型（荒漠草原>草甸>典型草原）、生活型、寿命和分类群之间存在差异。在整个北半球草原中，叶绿素浓度和叶绿素a/b与光合有效辐射和土壤氮磷比呈负相关，与年平均温度呈正相关。这些结果表明，草原中的叶绿素受草的分层结构、独特的高原环境和系统发育的影响。叶片氮素向叶绿素分配的模式在不同区域和草地类型之间存在差异，这表明如果单独将单叶氮或叶绿素与生产力简单关联时需谨慎。这些发现增强了我们对天然草原叶绿素的大规模理解，同时也为生态预测模型提供了信息。
