中国内蒙古温带典型草原植物物候对降水格局改变的响应

发布时间：2019-05-16 08:32

【摘要】：随着人类工业化进程的推进,全球气候发生了显著的变化。大气二氧化碳浓度升高,并由此导致了气候变暖以及伴随发生的降水格局变化。大量的控制实验研究和模型预测都表明在未来极端降水事件会显著增多,包括极端干旱和极端洪涝。植物物候是对气候变化响应最为敏感的指标之一,一直被作为植物应对气候变化的指示性指标。以往的研究往往只关注于干旱或者增雨对物候的影响,缺乏关于降水格局变化对植物物候影响的系统认识。半干旱草原是降水限制的主要生态系统类型之一。其植物物候在未来气候变化情景下会如何变化尚不清楚。为了研究半干旱草地植物物候对全球变化的响应,我们于2010-1012年在内蒙古半干旱草原设计了一项包括七个降水梯度(增雨20%,40%,60%;自然降雨,减雨20%,40%,60%)的控制实验。为了研究水分干扰后植被的生产恢复能力,我们于2013年停止降水梯度处理。在本实验平台上,我们在2012生长季后期选取了3个优势物种进行了物候研究,并于2013-2014年选取了群落中的10个常见物种进行研究。通过三年的物候观测数据,结果表明:(1)在处理年份(2012年),不同物种的物候对不同的降雨梯度有差异性响应。减雨60%使得克氏针茅在花期推迟了7.8天,增雨对克氏针茅的花期无显著影响。冷蒿物候对降水梯度的变化无显著响应。这可能是由于冷蒿是一种半灌木,根系发达,吸收能力强,因而对环境水分的改变不敏感。减雨和增雨条件下糙隐子草的开花时间均提前,可能是由于它本身植株矮小,对光的需求可能大于对水的需求。(2)在恢复年份植物物候对前期处理的响应与处理年份不同。与2012年干旱推迟针茅花期不同,在2013年,在干旱处理中针茅的开花时间比对照提前11.2天(P0.001),这可能是由于前期处理中,降雨减少导致的干旱降低了群落盖度,以及减少某些物种的数量,针茅受到的竞争压力比对照处理低。另外在恢复时期当水分不再受到限制,植物对地下的竞争转为地上光的竞争,针茅本身植株较高,对光的竞争优势强,植物生长更为迅速。(3)在恢复阶段植物群落整体花期提前。在干旱恢复期(2013-2014),禾草和非禾草分别显著提前开花物候2.3(P0.05)和0.9天(P0.1);早期开花物种和晚期开花物种分别提前开花1.9(P0.05)和2.2天(P0.05)。这说明在整个群落水平上物候提前,这可能是由于在干旱的内蒙古草原植被后代对干旱的响应是一种进化上的适应,通过提前开花来躲避干旱。我们的实验证明了在降水改变的条件下,不同植物由于其植株高度、根系吸水状况不同对降水改变的响应不同。在恢复期,由于植物对干旱环境适应的快速进化适应,群落水平物候整体提前。这种机制有利于植物在干旱胁迫后快速适应环境恢复生态系统生产。本研究对全球变化背景下的物候预测提供了一定的数据支持,并且对于当地草地生态系统管理具有一定的指导意义。
[Abstract]:With the advancement of the human industrialization process, the global climate has changed significantly. The concentration of carbon dioxide in the atmosphere is raised and thus results in a change in the climate warming and the resulting precipitation pattern. A large number of control experiments and model predictions show a significant increase in extreme precipitation events in the future, including extreme drought and extreme flooding. Plant phenology is one of the most sensitive indicators for climate change response and has been used as an indicator of plant response to climate change. Previous studies have been focused on the effects of drought or rain on the phenology, and the lack of systematic knowledge about the effect of precipitation pattern on the phenological effects of plants. Semi-arid grassland is one of the main ecosystem types of precipitation limitation. The change of plant phenology in future climate change scenarios is not clear. In order to study the response of plant phenology to global change in semi-arid grassland, we designed a control experiment including seven precipitation gradients (20%,40%,60%, natural rainfall,20%,40%,60%) in the semi-arid grassland of Inner Mongolia in 2010-1012. In order to study the recovery and recovery of vegetation after water disturbance, we stopped the precipitation gradient treatment in 2013. In this experimental platform, we selected three dominant species in the late season of 2012 and studied 10 common species in the community in 2013-2014. The results show that: (1) In the year of treatment (2012), the phenology of different species has a differential response to different rainfall gradients. The effect of precipitation on the flowering stage of Stipa grandis was delayed by 60%. There was no significant response to the change of the precipitation gradient. This may be due to the fact that the cold artemisia is a semi-shrub, the root system is developed, the absorption capacity is strong, and thus the change of the environment moisture is not sensitive. The flowering time of the rough and hermit grass is in advance under the conditions of rain-reducing and rain-increasing, which may be due to the short stature of the plant itself, and the demand for light may be larger than the water demand. (2) The response of the plant phenology to the previous treatment in the recovery year is different from that of the treatment year. In 2013, the flowering time of the Stipa grandis in the drought treatment was 11.2 days earlier than that in the control (P0.001), which may be due to the decrease in the degree of community coverage and the reduction of the number of certain species due to the early treatment, The competition pressure of the Stipa grandis is lower than that of the control. In addition, when the water content is no longer restricted during the recovery period, the competition of the plants to the underground is converted into the competition of the ground light, the plants of the Stipa are higher, the competition advantage of the light is strong, and the growth of the plants is more rapid. And (3) the whole flowering period of the plant community is advanced in the recovery stage. In the period of drought recovery (2013-2014), the early flowering of grass and non-grass was 2.3 (P0.05) and 0.9 days (P0.01), and the early flowering and late flowering species were flowering 1.9 (P0.05) and 2.2 days (P0.05). This indicates that there is an advance in the whole community level, which may be due to an evolutionary adaptation to the drought response in the drought-affected Inner Mongolia grassland, and to avoid the drought by early flowering. Our experiment shows that under the condition of the change of precipitation, the response of different plants to the change of precipitation is different due to the height of the plant and the water absorption of the root system. In the recovery period, the community level is advanced as a result of the rapid evolution adaptation of the plant to the drought environment. The mechanism is beneficial to the rapid adaptation of plants to the production of the ecosystem after drought stress. This study provides some data support for phenological prediction in the background of global change, and has certain guiding significance to the local grassland ecosystem management.
【学位授予单位】：河南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S812

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