【作者】 王成磊；

【导师】 张文辉； 何景峰；

【作者基本信息】 西北农林科技大学 ， 园林植物与观赏园艺， 2011， 硕士

【摘要】 以黄土高原丘陵沟壑区沙棘人工种群为研究对象,通过典型样地调查、室内分析,对沙棘种群有性和无性繁殖、干物质分配以及人工林天然化发育评价进行了系统的研究,分析了沙棘人工种群在黄土高原丘陵沟壑区的最适生长区域,阐明了人工种群天然化发育基本特性,为沙棘人工种林持续经营提供了依据。主要研究结果如下:(1)在黄土高原丘陵沟壑区,沙棘人工种群在4种生境中均能开花结实,但种子落地后很少能够成苗定居,有性生殖在该区很难维持种群更新。光照对沙棘结实产生积极影响,但水热组合条件欠佳是限制种子萌芽成苗的关键因素。(2)沙棘人工种群的天然更新,主要依靠无性繁殖产生的根蘖苗以及平茬后产生的萌生苗。根蘖苗在种群扩展中作用较大,根系水平疏松扩展;母株被平茬后,主要萌生于平茬高度为5cm的伐桩上。各生境沙棘萌芽力排序为沟底>阴坡>峁顶>阳坡。影响沙棘无性繁殖的主要环境因素是水分、光照。不同生境的沙棘人工种群年龄结构均为进展型,幼龄个体多、老龄个体少,表明沙棘人工种群具有较强的无性繁殖扩展能力。虽然成年植株有枯死和枯梢现象发生,但是沙棘种群幼苗数量丰富,能够实现自我更新,种群可以实现天然化发育。(3)天然化发育过程中,外部环境的变化导致物种多样性发生相应的变化,其中水分是关键性因子。沙棘群落在黄土丘陵区发育较好,可以实现自我更新而不衰退,具有天然群落应有的水土保持功能,说明沙棘人工林群落能够天然化发育。(4)通过不同生境条件下沙棘无性系地上生物质总干重比较结果为:沟底>阴坡>峁顶>阳坡;不同生境无性系标准株根冠比呈现出:沟底(1:1.56)<阴坡(1:1.08)<峁顶(1:0.72)<阳坡(1:0.61)。说明随着土壤水分降低,黄土丘陵沟壑区沙棘种群采取了以减少地上部生物量、扩大地下根系的方式来适应干旱环境的繁殖策略。(5)通过应用模糊隶属函数评判模型,应用种群的年龄结构;群落组成、结构和物种多样性;枯枝落叶层厚度,土壤结皮;土壤水分、养分等指标,对4个生境沙棘人工林的天然化发育进行综合评价,所得结果与当地沙棘人工林的生长发育状况相符合。沙棘人工林的天然化发育大小依次是:沟底>阴坡>峁顶>阳坡。更多还原

【Abstract】 In this paper, the artificial Hippophae rhamnoides population are taken as the research object in the gullied loess plateaus. Through the investigation of typical sample plots and laboratory experiment, this paper conducts a systematic study about the biological-ecological characteristics, community structure characteristics, population characteristics of sexual reproduction and asexual reproduction, dry matter allocation, as well as the evaluation method for the plantation communities naturalized development, identifies the optimum growth of regional of artificial Hippophae rhamnoides population in the gullied loess plateaus, and provides basis for the natural cultivation of the artificial Hippophae rhamnoides population. The main results are as follows:(1) In the gullied loess plateaus, the flowering, fruiting and seeds scattering of artificial Hippophae rhamnoides population are normal, and the seed yield is relatively high. But after the seeds fall, there are little to settle. The sexual reproduction is difficult to maintain the population regeneration in this region. Light has a positive impact on Hippophae rhamnoides, but water and temperature bad is a key factor which limits the seed germination growing into seedling.(2) The natural regeneration of artificial Hippophae rhamnoides population mainly depend on root sucker and root sprout after stumping, they are both produced by the asexual propagation of stock plant. Root sucker plays a more important role in the expansion of population, mainly in guerilla distribution; after stumping, root sprout initiates from 5cm high stump. Asexual propagation of Hippophae rhamnoides in gully bottom is more vigorous than that in others, just as gully bottom>shade slope>replat top>sunny slope. The major environmental factors affect the asexual propagation of Hippophae rhamnoides are water and light.Statistic the age structure of clonal ramets and the result shows: Artificial Hippophae rhamnoides population in different habitats all present the phenomenon of more young individuals and less older individuals. The phenomenon indicates artificial Hippophae rhamnoides population have the strong expansion capacity. The death and whither of population have little impact on artificial Hippophae rhamnoides population, because there are enough ramets to maintain the population regeneration, and they can achieve natural development.(3) Species diversity changes with the change of external environment in the period of development. The water is key factor. In the gullied loess plateaus, Hippophae rhamnoides population which is good and vigorous, have function of conservation of soil and water. So they can achieve natural development.(4) The comparison results of total clonal dry weight in different habitats as follows: gully bottom>shade slope>replat top>sunny slope; the root-shoot ratio of standard plants are: gully bottom (1:1.56)<shade slope (1:1.08)<replat top (1:0.72) <sunny slope (1:0.61). These show that artificial Hippophae rhamnoides population in the gullied loess plateaus through the way of reducing the dry weight on the ground and expanding the underground root system to adapt to arid environment with water reducing.(5) In the paper, using structure of age, structure of community, diversity of species, thickness of dead branches deciduous layer, soil crust, nutrient and moisture of soil, and so on. Based on fuzzy membership function synthetic evaluation model, the plantation community naturalized development was evaluated. The result shows that gully bottom>shade slope>replat top>sunny slope.更多还原