增温和光周期变化对东北地区兴安落叶松主要物候期的影响

Effects of warming and photoperiod change on main phenological phases of Larix gmelinii in Northeast China

兴安落叶松在东北地区森林生态系统的结构与功能中起着重要作用,气候变化背景下东北地区气温增加且光照缩短必将影响兴安落叶松的变化,特别是物候这一气候变化的敏感指标。弄清其物候对气候变化的响应有助于揭示兴安落叶松的变化趋势。但是,当前关于兴安落叶松物候对温度、光周期及其协同作用的响应机制仍不清楚。针对东北地区温度剧增、日照时数减少的特点,2019年4月至11月开展了3年生兴安落叶松幼苗主要物候期响应温度和光周期变化的大型人工气候室模拟控制实验。结果表明:(1)不同程度的增温对兴安落叶松生长周期(展叶始期至完全变色期)无显著影响,但显著缩短生长盛期(展叶盛期至叶变色普期),且增温2.0℃较增温1.5℃对生长盛期影响更大。(2)长光照显著增加兴安落叶松的生长周期(9.25 d),短光照对兴安落叶松生长周期的影响不显著,且长光照和短光照均使兴安落叶松生长盛期缩短,二者对兴安落叶松生长盛期影响表现一致。(3)长光照、短光照分别与增温协同作用均使兴安落叶松生长盛期缩短,其中增温2.0℃与长光照协同作用对生长盛期缩短更显著(34.67 d)。(4)与生长始期(展叶始期)和末期(完全变色期)相比,兴安落叶松生长盛期对温度响应更敏感,除叶变色普期外,兴安落叶松物候温度敏感度均随温度升高而降低。不同增温条件下,光照减少降低叶变色始期的温度敏感度,但增温1.5℃时光照减少降低展叶盛期的温度敏感度,增加叶变色普期的温度敏感度;增温2.0℃则相反。东北地区气候变化不利于兴安落叶松生长,且增温2.0℃较增温1.5℃更为不利。研究结果可为理解东北地区生态系统结构与功能变化提供依据。

Larix gmelinii forest plays an important role in the structure and function of forest ecosystem in Northeast China.In the context of climate change,the increase of temperature and the decrease of light in Northeast China will affect the change of Larix gmelinii forest,especially its phenology,a sensitive index of climate change.Understanding the response of phenology to climate change is helpful to reveal the change trend of Larix gmelinii.However,the response mechanism of Larix gmelini phenology to temperature,photoperiod and its synergistic effect is still unclear.According to the fact of increasing temperature and decreasing sunshine duration in Northeast China,a large-scale artificial climate chamber simulation experiment was conducted from April to November 2019 to understand the response of main phenological stages of Larix gmelinii seedlings with 3-year old to the changes of temperature and sunshine duration.The results indicate that:(1)Different degrees of warming had no significant effect on the growth cycle of Larix gmelinii(from the first stage of leaf unfolding to the complete discoloration stage),but significantly shortened the peak growth period(from the peak stage of leaf unfolding to the leaf discoloration in general).The effect of 2.0℃warming on the growth peak was greater than that of 1.5℃warming.(2)The growth cycle of Larix gmelinii significantly increased(9.25 days)with long sunshine duration,but the effect of short sunshine duration on the growth cycle of Larix gmelinii was not significant,and both long and short sunshine duration shortened the peak growth period of Larix gmelinii,and had the same effect on the peak growth period of Larix gmelinii.(3)The interaction between sunshine duration and increasing temperature shortened the peak growth period of Larix gmelinii,and the interaction between 2.0℃warming and long sunshine duration had more significant to shorten the peak period of growth(34.67 days).(4)Compared with the initial growth stage(the first stage of leaf unfolding)and the final growth stage(complete discoloration stage),the peak growth stage of Larix gmelinii was more sensitive to temperature.The temperature sensitivity of phenology of Larix gmelinii decreased with the increase of temperature except the leaf discoloration in general.Under the conditions of different increasing temperatures,the decrease of sunshine duration decreased the temperature sensitivity at the leaf discoloration onset,however,when the temperature increased by 1.5℃,the decrease of sunshine duration decreased the temperature sensitivity at the peak stage of leaf unfolding and increased the temperature sensitivity at the leaf discoloration in general,while it was the opposite under 2.0℃warming.This indicates that climate change in Northeast China is not conducive to the growth of Larix gmelinii,and that 2.0℃warming is more unfavorable than 1.5℃warming.The results can provide a basis for understanding the changes of ecosystem structure and function in Northeast China.