Key Laboratory of Humid Subtropical Eco-geographical Process of Ministry of Education, School of Geographical Sciences, Fujian Normal University, Fuzhou, China; Fujian Sanming Forest Ecosystem National Observation and Research Station, Sanming, China; State Key Laboratory of Humid Subtropical Mountain Ecology, Fujian Normal University, Fuzhou, China.
Key Laboratory of Humid Subtropical Eco-geographical Process of Ministry of Education, School of Geographical Sciences, Fujian Normal University, Fuzhou, China; Fujian Sanming Forest Ecosystem National Observation and Research Station, Sanming, China; State Key Laboratory of Humid Subtropical Mountain Ecology, Fujian Normal University, Fuzhou, China.
Sci Total Environ. 2024 Jul 10;933:173147. doi: 10.1016/j.scitotenv.2024.173147. Epub 2024 May 11.
Plant phenology plays an important role in nutrient cycling and carbon balance in forest ecosystems, but its response to the interaction of global warming and precipitation reduction remains unclear. In this study, an experiment with factorial soil warming (ambient, ambient +5 °C) and precipitation exclusion (ambient, ambient -50 %) was conducted in a subtropical Chinese fir (Cunninghamia lanceolata) plantation. We investigated the effects of soil warming, precipitation exclusion, and their interactions on Chinese fir phenology involving tree height and fine root growth. In the meantime, the impact of tree height growth and related climatic factors on fine root production was also assessed. The results showed that: (1) more variable phenology responses were observed in fine root growth than in tree height growth to the climatic treatments; the duration of fine root growth and tree height growth was significantly reduced by the precipitation exclusion and warming treatment, respectively; phenology differences of fine root and tree height growth caused by the solo warming and precipitation exclusion treatment were further enhanced by the combined treatment; and despite the greater inter-annual phenology stability of tree height growth than that of fine root growth, both of them showed insignificant response to all the climate treatments; (2) asynchrony of phenology between tree height and fine root growth was significantly enlarged by solo warming and precipitation exclusion treatments, and further enlarged by the combined treatment; (3) fine root production was significantly and positively correlated with air, and soil temperature, and tree height growth as well, which was altered by warming and precipitation exclusion treatments. Our results demonstrated that climatic changes significantly and differently alter phenology of, and extend the phenology asynchrony between, above and below ground plant components, and also highlight the climate-sensitive and variable nature of root phenology. Overall, these phenology responses to climatic change may weaken the close link between fine root production and tree height growth, which may result in temporal mismatch between nutrient demand and supply in Chinese fir plantation.
植物物候在森林生态系统的养分循环和碳平衡中起着重要作用，但它对全球变暖与降水减少的相互作用的响应仍不清楚。本研究在亚热带杉木（Cunninghamia lanceolata）人工林内进行了一个包括土壤增温（常温、常温+5°C）和降水排除（常温、常温-50%）的因子实验，研究了土壤增温、降水排除及其相互作用对杉木物候（包括树高和细根生长）的影响。同时，还评估了树高生长及其相关气候因素对细根生产的影响。结果表明：（1）与树高生长相比，细根生长对气候处理的物候响应更为多变；降水排除和增温处理分别显著缩短了细根和树高生长的时间；单独的增温和降水排除处理引起的细根和树高生长物候差异，在联合处理下进一步增强；尽管树高生长的年际物候稳定性大于细根生长，但两者对所有气候处理均无显著响应；（2）单独的增温和降水排除处理显著扩大了树高和细根生长之间的物候异步，联合处理进一步扩大了这种异步；（3）细根产量与空气和土壤温度以及树高生长显著正相关，而增温和降水排除处理改变了这种相关性。研究结果表明，气候变化显著且不同地改变了地上和地下植物组成部分的物候，并扩大了它们之间的物候异步，突出了根物候的气候敏感性和变异性。总体而言，这些对气候变化的物候响应可能会削弱细根生产与树高生长之间的紧密联系，导致杉木人工林养分需求与供应之间的时间不匹配。
