【作者】 王静；

【导师】 杨持；

【作者基本信息】 内蒙古大学 ， 生态学， 2003， 博士

【摘要】 冷蒿(Artemisia frigida)种群耐干旱、耐践踏、耐土壤侵蚀、生根萌蘖的再生生长能力很强,在牲畜强烈啃食及土壤侵蚀的状况下,仍然能够继续更新繁殖,使草场在强度利用条件下,尚可保持一定的生产力水平,在阻击草原群落的进一步退化上起着十分重要的作用。本文从形态、生理、遗传多样性角度出发,在借鉴现有研究成果的基础上,运用植物种群生态学、植物生理生态学、种群遗传学的研究方法,探讨了冷蒿种群对放牧干扰的响应,研究结果如下:1.随着放牧强度的增加,冷蒿营养枝、生殖枝高度下降;营养枝密度、不定根密度和匍匐茎长度增加;生殖枝密度和生殖枝分化率呈下降趋势,生殖格局由有性生殖和无性繁殖并存向无性繁殖为主转变。生殖格局的调整是冷蒿种群在重牧下成为建群种的关键。2.随着放牧强度的增加,冷蒿种群营养构件及总生物量增加。生物量资源分配从静态上看,增加根的分配,减少茎叶的分配;增加无性繁殖的分配,减少有性生殖的分配;从动态上看,生长初期到盛期资源优先分配给地上部分,盛期到末期资源优先分配给有性生殖及储藏器官。资源分配格局变化是冷蒿种群耐牧,在重牧下成为建群种的基础。3.随着放牧强度的增加,冷蒿种群可溶性糖含量变化不显著,淀粉含量降低,非结构碳水化合物(TNC)含量降低。营养构件的非结构碳水化合物库和总非结构碳水化合物库均增加。同时冷蒿种群非结构碳水化合物库对根的分配增加,而对茎、叶的分配减少;对“源”的分配减少,对“库”的分配增加;对可逆贮藏库分配增加,对不可逆贮藏库的分配减少。对有性生殖的分配减少,对无性繁殖的分配增加。体现出冷蒿种群在放牧干扰下,减少能量损失,增加可利用能量,提高再生生长能力,提高种群的适合度,响应和适应放牧干扰的生态对策。4.随着放牧强度的增加,冷蒿体内叶绿素a、叶绿素b及总叶绿素含量变化不大。冷蒿叶片中脯氨酸含量迅速积累,在生长初期尤为显著,但是叶片中MDA含量、保护酶变化不显著。冷蒿根中脯氨酸含量较少,生长初期保护酶POD、SOD活性下降,致使MDA大量累积,表明细胞膜脂过氧化程度增加;生长末期SOD、POD、CAT活性增加,MDA含量变化不显著。地上部分脯氨酸的积累,地下部分保护酶活性的变化对冷蒿种群抵抗放牧逆境起到重要作用。5.随着放牧强度的增加,冷蒿体内ABA含量增加,IAA、GA和ZR的含量基本呈下降趋势。ZR含量下降使放牧胁迫信号从根传输到冠,ABA大量积累,ABA更多还原

【Abstract】 Artemisia frigida population can tolerate drought, browsing, trample and soil erosion. It has strong regenerating ability of radication and germination, and can still renew and reproduce under intensive livestock browse and soil erosion. It helps pasturage keep certain productivity under utilization intensity. Thus it plays a very important role in preventing the community from further degeneration. The study discussed A. frigida population response to grazing interference through variances of morphological characters, physiological characters, genetic diversity under different grazing intensities. The results were as follow:1. With the increase of grazing intensity, height of vegetative shoot and reproductive shoot decreased, density of vegetative shoots and adventitious roots increased, length of stolen increased, density of reproductive shoots and the differentiation ratio of reproductive shoots (reproductive shoots density/total shoots density) trend to decrease. With the increase of grazing intensity, the reproductive pattern changed from sexual and asexual reproductive to asexual reproductive mainly, the changeover was the key for A. frigida to become constructive species under heavy grazing.2. With the increase of grazing intensity, a. frigida population biomass of leaves, stems, roots and total biomass increased. the static change was that biomass allocation to roots increased, while that to stems and leaves decreased; biomass allocation to asexual reproductive increased, while that to sexual reproductive decreased. the dynamic change was that the biomass allocated priority to above ground portion from early to middle growth period, especially to leaves; the biomass allocated priority to sexual reproductive or storage organs from middle to late growth period, the change of resource allocation pattern was the material base for a. frigida to become constructive species under heavy grazing.3. With the increase of grazing intensity, soluble sugar content had no significant change, except it decreased in late growth period. With the increase of grazing intensity, starch content and total nonstructural carbohydrate (TNC) content decreased, nonstructural carbohydrate pool of leaves, stems, roots and TNC pool increased. The allocation of nonstructural carbohydrate pool to roots increased, while that to stems and leaves decreased; the allocation to reversible storage pool increased, while that to irreversible storage pool decreased; the allocation to sexual reproductive decreased, while that to asexual reproductive increased. All these were ecological strategies that A. frigida population adopted to reduce energy losing, enhance utilized energy, advance the capability of regeneration and the fitness of population, and to adapt and respond to grazing interference.4. With the increase of grazing intensity, chlorophyll a, b and total chlorophyll had no更多还原