【作者】 崔秀萍；

【导师】 刘果厚；

【作者基本信息】 内蒙古农业大学 ， 水土保持与荒漠化防治， 2007， 博士

【摘要】 黄柳作为浑善达克沙地重要的固沙先锋灌木,对沙地生态环境的改善起着十分重要的作用,本研究对黄柳的形态结构适应性、种子天然更新规律以及人工更新复壮、生理适应性等方面进行了一系列的探索研究,揭示了黄柳在沙地的生理生态适应对策,论文通过研究得出了以下主要结论:黄柳叶片叶肉全栅化,为等面叶,上、下表皮细胞外壁加厚且均具角质层,是典型的沙生灌木的形态结构特征;由于小生境的不同,叶片在形态结构上亦表现有差异,抗旱性大小顺序依次是:流动沙丘的黄柳>半固定沙丘的黄柳>固定沙丘的黄柳>丘间低地小红柳。黄柳叶片具有较厚的角质层、叶肉全栅化、没有海绵组织分化等旱生植物的特征,因此,从叶片的形态解剖结构角度来分析,也证实了其是旱中生灌木。通过对黄柳从栽植开始到长势旺盛时的根系分布特征和生物量的研究发现:人工栽植黄柳的根系主要由直径<2.0mm的中根和细根构成,其中又以直径<0.5mm细根所占比例最高,其数目占剖面根系总数的50%以上。根系主要分布在10～30cm的土层中,以吸收这一土层内的水分和养分;根系重量在各土层中呈随土层深度加深而降低的分布趋势;根系呈水平分布,水平根发达,随着植株的不断生长,这一特征愈加明显。黄柳种子萌发和幼苗生长受多种环境因子的影响,黄柳种子对水分条件敏感,发芽的适宜土壤含水量为3%～20%;种子萌发需要沙土覆盖,适宜覆沙厚度为0.1～0.4 cm,但当沙埋厚度超过0.6cm时,种子出苗就会受到抑制;种子发芽的适宜温度为15℃～35℃,当温度高于45℃时种子将不能萌发,且种子最终死亡;黄柳种子是光中性种子,光照和黑暗条件下的发芽率无显著性差异;幼苗的耐热性较强,40℃处理下幼苗才出现热害症状,并且热害症状发展缓慢,60℃处理下90min后幼苗才会干枯死亡;在室内贮藏条件下,黄柳种子的寿命为120d左右。结合野外调查情况和实验室实验可看出,黄柳的种子萌发和幼苗生长受多种自然因子的影响,黄柳是采用多种子、高萌发、低存活的繁殖策略以适应沙地环境,属于r型对策者。黄柳有种子更新和萌蘖更新两种更新方式,但由于种子发芽和幼苗的形成受温度、水分及沙埋情况等多项因子的综合影响,种子更新困难。随着沙丘的逐渐固定,黄柳地上部分逐渐老化,开始出现衰退甚至逐渐死亡现象,这时可利用黄柳具有萌蘖的特性,采取人工平茬措施,达到复壮更新的目的,平茬灌丛新生枝条长度比未平茬灌丛约长150cm,最长当年生新枝达277cm;平茬灌丛新生枝基径也比未平茬的约粗0.5cm,最粗的为1.32cm;平茬黄柳灌丛叶片长平均约为8cm,叶宽平均约为0.6cm,而未平茬灌丛叶片平均长为5.3cm,叶片宽平均为0.4cm。可见,平茬不但增加了黄柳灌丛的生物量,亦提高了家畜可食部分(叶+嫩茎)的比例,同时增大了郁闭度,增强了防风固沙效果。在水分亏缺条件下,黄柳叶片含水量和相对含水量较多,束缚水含量高,持水能力较强;随着水分亏缺程度的增加,黄柳叶片的可溶性糖含量和Pro含量均增加,对黄柳均有渗透调节作用;黄柳SOD活性和POD活性增加,且与CAT的进行了较好的协调作用,以减缓自由基对细胞膜系统的伤害;黄柳叶片中MDA含量逐渐增加,说明膜系统的伤害程度也随水分亏缺程度的增加而加剧。因此,在生理特性上,黄柳亦表现出了对沙地干旱环境的适应特性。更多还原

【Abstract】 Salix gordejevii is a kind of dune-fixing pioneer shrub in Hunshandak Sandland, China. Salix gordejevii takes a vital role in improvement of ecological environment .We had conducted a series of explorative research, which included morphological and structural adaptability, physiological adaptability, regular of natural regeneration and artificial regeneration and restoration and so on. Eco-physiological adaptability countermeasures of Salix gordejevii were showed, with main conclusions being achieved as follows:The leaves of Salix gordejevii, under all the observed habitats, were thicker with total-palisade type, identical face leaf and thicken epidermis cell wall with cuticle. Its structural characteristics were typical psammophyte. The results also showed that the sequence of drought resistance is in the order of Salix gordejevii on the drifting sand dune, Salix gordejevii on the semi-fixed sand dune, Salix gordejevii on the fixed sand dune and Salix microstachya var. bordensis. Meanwhile, from a structure of leaves perspective, Salix gordejevii were confirmed which it is a xeromesophytes.The main conclusions being achieved by studied on root system distribution and biomass of Salix gordejevii: Artificial forest root system were made up fine root and middle root (diameter<2.0mm),and fine root(diameter<0.5mm) took high proportion. The fine root took more than 50% of the total amount. Root system of Salix gordejevii mostly distributed in 10~30cm depth of soil ,and in order to absorb the moisture content and nutrient in this soil layer; with deepened soil layer, The weight of root system took on reduced tendency; The root system took on the level distribution, and the horizontal root system was developed. At the same time, with the plant growth, the characteristic would even more obvious.Seed germination characters and seedling development of Salix gordejevii were affected by some environmental factors. In this research the soil moistures, soil thickness, temperature and light that influenced the seed germination and seedling development were studied. The results showed: Seeds were very sensitive to water. The optimal sand water content for seed germination was 3% to 20%. If sand water content was less than 3% or more over 20%, seed could not germinate; Seed germination needed sand bury. The optimal sand thickness was 0.1cm to 0.4cm. However, when the sand that buried seed was thicker than 0.6 cm, seedling emergence would be restrained. When the sand was thicker than 1.2cm, seed would not germinate; The optimal temperature for seed germination was 15℃to 35℃. When the temperature was higher than 45℃, seed could not germinate, and died finally; Heat tolerance of the seedling was strong. Seedling will be damaged when temperature was 40℃, and died after 90min when temperature was 60℃; Seed longevity was about 120d when seed were stored under the indoor condition.Salix gordejevii belongs to r-countermeasure type, which was more seed, high germination rates and lower livability. The regenerate manners of Salix gordejevii had seed regeneration and sprouting regeneration, but seed regeneration was hard. At the same time, growth of Salix gordejevii would decline when the drifting sand dune was fixed.In order to achieve the purpose of regeneration and restoration, people might adopt cutting measure by making use of its characteristic. Therefore, not only the cutting increased biomass of shrub, but also edible parts, canopy density and effects of sand-fixing and sind-preventing.Under the conditions of water deficiency, relative water content , bound water content and water-holding capacity of Salix gordejevii were high; With increasing the degree of water deficiency, soluble sugar content and Pro content of leaves increased,and effect of osmoregulation to Salix gordejevii; The SOD activity and POD activity raised, and assorted with CAT, in order to mitigate hurt of O2-; The content of MDA raised gradually, and showed that hurtful degree of membrane protective system increased with increasing the degree of water deficiency. Therefore, as viewed from physiological characteristics, Salix gordejevii exhibits adaptive characteristics of drought too.更多还原