Key Laboratory of Grassland Resources of the Ministry of Education, Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization of the Ministry of Agriculture and Rural Affairs, Inner Mongolia Key Laboratory of Grassland Management and Utilization, College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Hohhot, China.
School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
Glob Chang Biol. 2021 Sep;27(17):4169-4180. doi: 10.1111/gcb.15718. Epub 2021 Jun 11.
Leaf senescence is known to be regulated by the plant hormone ethylene, but how leaf lifespan responds to global environmental change and links to ecosystem-level responses remains largely unexplored. Here we investigated the effects of climate warming and nitrogen addition on plant functional traits, plant hormone ethylene and net primary production in a 13-year field experiment in a desert steppe. Across the last 3 years of the experiment (2016-2018), plant productivity increased under warming only in 2016, when there was above normal precipitation, but consistently increased with nitrogen addition. Warming enhanced net photosynthesis, leaf nitrogen and ethylene production and reduced leaf lifespan in 2016 (a wet year), but not in 2017 (a drought year); the effect of warming in 2018 (a year with normal precipitation) was opposite to 2016, likely due to the below-normal precipitation in the mid-growing season in 2018. Nitrogen addition led to increases in leaf nitrogen, ethylene production and net photosynthesis, and declines in leaf lifespan in 2016 and 2018, but not in 2017. The ethylene-regulated lifespan was further evidenced by the addition of CoCl (an ethylene biosynthesis inhibitor) that reduced ethylene production and prolonged lifespan. Structural equation modeling showed that leaf lifespan had a negative effect on plant productivity, both directly and indirectly via its negative effect on net photosynthesis, across all 3 years. Our results demonstrate the divergent responses of leaf lifespan and, in turn, plant productivity to warming under inter-annual and intra-annual precipitation variation, thus linking plant hormone production, functional traits and ecosystem functioning in the face of global environmental change.
叶片衰老已知受植物激素乙烯的调控，但叶片寿命如何响应全球环境变化并与生态系统水平的响应相关联在很大程度上仍未得到探索。在这里，我们在沙漠草原进行了为期 13 年的野外实验，研究了气候变暖与氮添加对植物功能性状、植物激素乙烯和净初级生产力的影响。在实验的最后 3 年（2016-2018 年），仅在 2016 年降水高于正常水平时，变暖增加了植物生产力，但氮添加则持续增加了植物生产力。变暖增强了净光合作用、叶片氮含量和乙烯的产生，并缩短了叶片寿命，这仅发生在 2016 年（湿润年份），而在 2017 年（干旱年份）没有发生；2018 年（降水正常年份）的变暖效应与 2016 年相反，这可能是由于 2018 年生长季中期降水低于正常水平所致。氮添加导致 2016 年和 2018 年叶片氮含量、乙烯的产生和净光合作用增加，叶片寿命缩短，但在 2017 年没有发生。2016 年和 2018 年添加 CoCl（一种乙烯生物合成抑制剂）减少了乙烯的产生并延长了叶片寿命，这进一步证明了乙烯调控的叶片寿命。结构方程模型表明，叶片寿命对植物生产力有负面影响，这种影响既直接，也通过对净光合作用的负面影响间接产生，这种影响在所有 3 年中都存在。我们的结果表明，叶片寿命及其植物生产力对变暖的响应在年际和年内降水变化下存在差异，从而在全球环境变化背景下联系了植物激素产生、功能性状和生态系统功能。
