【作者】 徐伟红；

【导师】 王仁卿；

【作者基本信息】 山东大学 ， 生态学， 2009， 硕士

【摘要】 目前由于全球气候变化的影响,导致森林生态系统破坏,生态功能退化日益严重,恢复日益受损和退化的生态系统成为国际社会广泛关注的热点问题。植物通过各种不同的生理生态特征适应日益变化的环境,进行植物与环境之间相互关系及基本机制的研究成为现代植物生理生态学研究的重要内容。本研究选用刺槐(Robinia pseudoacacia L.)这种鲁中山区典型植被恢复物种,在房干实验基地,采用现代生理生态学分析方法和测量手段,研究在两种不同土壤基质下水分胁迫对其生理生态特征的影响,目的在于模拟未来可能出现的干旱环境下,待恢复山区和恢复区上刺槐林的适应机制,对于深入探讨刺槐作为鲁中山区恢复优势树种的可能性提供科学依据,并能指导合理抚育和管理不同恢复阶段山区树种以达到避灾减灾和增加成效的目的。通过控制实验模拟植被恢复前后变化了的土壤基质,每个基质下设置四个水分梯度,研究一年生刺槐幼苗形态结构、光合荧光、水分利用、生物量积累及其分配等生理生态特征对不同土壤基质及水分胁迫的响应机制。结果表明:同一基质下,随干旱胁迫程度的增强,株高、基径、总叶面积、总叶数、冠幅和叶面积指数等形态指标均逐渐降低;以叶面积和叶干重为代表的叶大小明显受到限制,叶片伸展性、叶长/叶柄长、最大宽度分割也存在显著差异;叶片相对含水量逐渐减少的同时,净光合速率、蒸腾速率和气孔导度逐渐减少,光能利用效率降低,同时电子传递速率受到明显抑制,有效量子产量逐渐降低,光化学淬灭和非光化学淬灭系数均显著降低,光系统的保护机制减弱,造成光抑制程度的加剧;相同时间失水率的不同说明严重胁迫下的叶片持水力普遍大于正常供水下的持水力;土壤水分含量的减少降低了各器官的生物量积累,同时影响生物量的分配方式,根生物量比增加,而叶生物量比降低,光合产物向地下部分尤其是侧根迁移,比叶面积逐渐降低。不同基质间,充分供水时,养分对于刺槐幼苗生长的制约作用大于水分的影响,腐殖性棕壤基质上幼苗的高度、总叶面积等形态特征,净光合速率、蒸腾速率、气孔导度等光合特征和生物量积累特征高于粗骨性棕壤基质下的幼苗;而在严重水分胁迫下,水分的供应严重不足,此时水分是影响植株生长的主要因素,由于粗骨性棕壤的保水能力要高于腐殖性棕壤,因此粗骨性棕壤基质的叶数,冠幅等指标开始高于腐殖性棕壤基质的相应部分,而粗骨土的净光合速率,蒸腾速率,气孔导度等光合特征也高于腐殖土基质的。两基质间叶形态特征也有不同,腐殖土基质的叶片大于粗骨土基质中的叶片,叶片伸展性也产生了差异;腐殖土基质下的叶绿素含量均高于粗骨土基质的,而叶绿素a/b则低于粗骨土的;粗骨土基质的各部分生物量的相对生长速率低于腐殖土基质的相应部分。刺槐幼苗通过多方面的适应调节机制,保证了幼苗在不同生境下的正常生长和生存,适应较大程度的干旱贫瘠环境,并使其能够适应未来较大程度的环境变化,因此也成为植被恢复的理想树种。更多还原

【Abstract】 Forest ecosystems suffer from severe destroy going with serious degradation of ecological functions just because of global climate changes at present. Restoring the increasing degraded ecosystems has become a hot point that is focused by many international communities. Plants adapt to the changing environment through a variety of physiological and ecological characteristics. In recent years, more and more researches are focused on the relationship and basic mechanism between the plants and environment. It has become an important aspect of modern plant ecophysiological researches.In this study, we chose Robinia pseudoacacia L. as the research object. We used modern ecophysiological equipments and measurements to study its physiological and ecological characteristics under different water stress of two soil matrixes in order to simulate the drought conditions of the unrecovered and being recovered mountain areas in the future. The results will provide a scientific basis for the possibility of R. pseudoacacia as the dominant species of the center of Shandong mountain areas. And it will help to provide the guidance and management of mountain species reasonably in different stages of ecological reconstruction.The two different soil matrixes were set to simulate the early and long-term vegetation restoration, and four different water supply levels of every matrix were conducted by artificial water control in the rainout shelters, in order to study the growth, morphological architecture, photosynthetic characters, water use characteristic, biomass accumulation and allocation in one-year old R. pseudoacacia seedlings respond to diverse soil matrixes and water stresses. The results showed that:With increased in water stress under the same matrix, morphological variables of height, stem diameter, total leaf area, total leaf number, crown area and leaf area index decreased. The leaf size, including leaf area, leaf mass, became smaller with a short supply of water, and leaf elongation, leaf length to leaf petiole, leaf widest division show significant differences. With the leaf relative water content decreasing, net photosynthetic rate, transpiration rate and stomatal conductance also decreased. Meanwhile, light use efficiency, electron transport rate, effective quantum yield, photochemical quenching and non-photochemical quenching are also reduced, as well as weak photoprotective effect in photosystem caused photoinhibition more serious. The difference of water lost rate after the same time indicates that the leaf moisture retaining power of severe water stresses generally greater than that of well watered condition. Biomass accumulations to each organ were restricted by the deficit of soil water content. Under water stress, biomass allocations were also affected, more photosynthetic products were transferred to belowground biomass, especially to the lateral roots. As a result, the root mass ratio increased, the leaf mass ratio decreased, and specific leaf area reduced gradually.In the well watered conditions between different matrixes, nutrients for the growth of R. pseudoacacia seedlings are more important than water stress. As a result, the morphological variables of height and total leaf area, photosynthetic characters such as net photosynthetic rate, transpiration rate and stomatal conductance, biomass accumulation and allocation of humous brown soil were obviously higher than those of regosol brown soil. But in the severe water stresses, water becomes the lethal factor, and several variables of the regosol brown soil were higher than those of humous brown soil just because the water retaining capacity of regosol brown soil is better than that of the humous brown soil. These variables included the total leaf number, crown area, net photosynthetic rate, transpiration rate and stomatal conductance. Leaf morphological parameters were also affected by the different soil matrixes. The leaf size of humous brown soil showed larger than that of regosol brown soil, along with the difference of leaf elongation. The contents of chlorophyll of humous brown soil were more than that of regosol brown soil, but the chlorophyll a/b was less. The relative growth rate of biomass accumulations to each organ in regosol brown soil was lower than that in humous brown soilIn conclusion, this research shows that the seedlings of R. pseudoacacia seedlings can respond and adapt to environmental changes through various mechanisms, by which the seedlings of R. pseudoacacia can be assured to normally grow and survive under drought and poor conditions, and may adapt to more fluctuant climate changes in the future. All of those mechanisms make R. pseudoacacia to be the ideal species for vegetation restoration.更多还原