KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 荒漠草本植物对降雨变化的光合响应及生长适应策略 | |
| Alternative Title | Photosynthetic response and growth adaptation strategies of desert herbaceous plants to rainfall variation |
| 闵孝君 | |
| Subtype | 博士 |
| Thesis Advisor | 马剑英 |
| 2020-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 理学博士 |
| Keyword | 降雨量 降雨频次 短命植物 光合作用 稳定同位素 Rainfall amount Rainfall frequency Ephemeral plants Photosynthesis Stable isotopes |
| Abstract | 近年来，人类活动的干扰和全球气候的变化正在改变全球水文循环，从而影响降水格局。 降雨量和频次的变化可能影响陆地生态系统结构和功能，尤其是受降水量限制的干旱与半干旱区。荒漠草本植物对早春沙丘的固定和营养循环具有重要作用， 研究降雨变化下草本植物的生长和适应策略对沙漠管理和保护具有理论意义。本研究选择古尔班通古特沙漠南缘较为平坦的丘间低地作为研究样地，开展了为期三年的降雨控制实验。 根据该地区历年来降雨数据，采用遮雨棚控制自然降雨，设置了降雨量（50%减雨、对照和 50%增雨）和降雨频次（3 d、 6 d 和 15d） 两个因素三水平的析因设计。 研究生长季降雨变化对草本植物层片特征、优势种植物个体生长和生理特征的影响， 探讨降雨量和降雨频次对荒漠草本植物的适应和生长策略， 揭示草本植物对降雨变化的适应机制。 实验结果如下：（1）降雨量的变化，主要影响草本层片植物盖度、地上生物量，对植物密度、物种多样性没有显著影响。 降雨量增加 50%条件下， 条叶庭荠（ Alyssumlinifolium Steph. ex Willd.）、 尖喙牻牛儿苗（Erodium oxyrhinchum M. Bieberstein）和琉苞菊（Centaurea pulchella Ledeb.） 的株高增高、叶片和花果数量增多。 降雨量减少 50%条件下， 条叶庭荠、 尖喙牻牛儿苗和琉苞菊提前开花、结实和凋谢，从而缩短其生活周期； 反之亦然。 少频次的大降雨（15 d）与降雨量增加具有相似的处理效应，都增加了尖喙牻牛儿苗和琉苞菊的生物量。 减少降雨量和增加降雨频次（3 d）都使得尖喙牻牛儿苗和琉苞菊遭受了干旱胁迫，减少其营养器官（叶片和茎）生物量分配，增加其生殖器官（花和果实）生物量；（2）随着降雨量的减少，尖喙牻牛儿苗和琉苞菊叶片光合速率下降，主要是由于气孔限制，数据也显示气孔导度和胞间 CO2 浓度下降；尖喙牻牛儿苗和琉苞菊气孔导度变化可以分别解释约 90%和 70%光合速率的变异。 降雨量减少处理下， 尖喙牻牛儿苗和琉苞菊内在水分利用效率（WUE） 提高，这是荒漠草本植物在不利环境条件下生存的重要策略；（3）降雨量减少条件下， 优势种植物叶片 δ13C 增大，即水分利用效率升高，与气体交换参数计算的内在水分利用效率一致，主要是长期气孔限制所致。 相反，植物叶片 δ15N 减小，这与氮代谢过程中相关酶活性降低有关。 降雨变化下，叶片 δ13C 对植物光合作用和 WUE 有较好指示作用， 而 δ15N 对植物生物量具有更好的指示作用。本研究表明， 降雨量的变化对古尔班通古特沙漠南缘草本层片特征的影响比降雨频次的变化更加重要。 此外，草本植物盖度和生产力对短期降雨变化响应明显，但是植物多样性没有受到降雨变化的显著影响；植物通过快速的形态和生理调节以及增加生殖器官生物量分配的生长策略，保障了草本层片物种多样性和组成的稳定。 长期降雨变化对草本植物的影响有待进一步的研究。 |
| Other Abstract | In recent years, the disturbance of human activities and the change of globalclimate have given rise to the variation in global hydrological cycle, thus affecting theprecipitation patterns. Changes in rainfall amount and frequency may affect thestructure and function of terrestrial ecosystems, especially in water-limited arid andsemi-arid regions. Desert herbs play an important role in the fixation and nutrientcycling of dunes in early spring. Therefore, it is of theoretical significance for desertmanagement and protection to study the growth and adaptation strategies of herbaceousplants under the scenario of changing rainfall patterns.In order to study the adaptation and growth strategies of desert herbaceous plantsto changing rainfall amount and frequency, a three-year rainfall simulation experimentwas conducted in the southern edge of the Gurbantonggut desert. According to thehistorical rainfall data in this region, natural rainfall was controlled by rain-shelter, anda factorial design of rainfall (50% reduction, control and 50% increase) and rainfallfrequency (3 d, 6 d and 15 d) was applied with five replicates. The characteristics ofherbaceous layer, individual growth and leaf characters of dominant species weredetected under different rainfall treatments in growing season. The results are as follows:(1) the change of rainfall amount mainly affected the cover and abovegroundbiomass of herbaceous layer, but had no significant effect on plant density and speciesdiversity. Under the condition of the rainfall amount increased by 50%, the plant height,number of leaves, flowers and fruits in Alyssum linifolium, Erodium oxyrhinchum andCentaurea pulchella increased significantly. Under the condition of the rainfall amountdecreased by 50%, A. linifolium, E. oxyrhinchum and C. pulchella blossomed, fruitedand withered in advance, thereby shortened the life cycle, vice versa. Low frequencybut larger rainfall amount (15 d) had a similar treatment effect with increased rainfallamount, both increased the biomass of E. oxyrhinchum and C. pulchella. Reducing rainfall amount or increasing rainfall frequency (3 d) made E. oxyrhinchum and C.pulchella suffer from drought stress, reduced the biomass distribution of vegetativeorgans (leaves and stems), while increased the biomass of reproductive organs (flowersand fruits).(2) With the decrease of rainfall amount, the photosynthetic rate decreased in E.oxyrhinchum and C. pulchella, mainly due to stomatal limitation. The data also showedthat stomatal conductance and intercellular CO2 concentration decreased. The variationof stomatal conductance in E. oxyrhinchum and C. pulchella could explain about 90%and 70% variation of their photosynthetic rate, respectively. Under the reduced rainfallamount treatment, the intrinsic water use efficiency of E. oxyrhinchum and C. pulchellawas improved, which is an important strategy for desert herbs to survive in adverseenvironmental conditions.(3) Under the condition of reduced rainfall amount, the foliar δ13C in E.oxyrhinchum and C. pulchella increased, that is, the water use efficiency increased,which was consistent with the intrinsic water use efficiency calculated by gas exchangeparameters, mainly due to long-term stomatal limitation. In contrast, foliar δ15N in E.oxyrhinchum and C. pulchella decreased under the reduced rainfall amount, whichcould be related to the decreased activity of related enzymes during nitrogenmetabolism. Under the rainfall variation, foliar δ13C could be used a good indicator ofplant photosynthesis and WUE, while δ15N could be used an indicator of plant biomass.This study showed that the change in rainfall amount is more important than thechange in rainfall frequency for the variation in characteristics of herbaceous layer inthe southern edge of the Gurbantonggut desert. In addition, herbaceous plants haverelatively limited response in short-term rainfall change due to high stability. Theeffects of long-term rainfall change on herbaceous plants are in need of further study. |
| Subject Area | 生态学 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15439 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 闵孝君. 荒漠草本植物对降雨变化的光合响应及生长适应策略[D]. 北京. 中国科学院大学,2020. |
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