【作者】 李庆梅；

【导师】 刘勇；

【作者基本信息】 北京林业大学 ， 森林培育， 2008， 博士

【摘要】 球果和种子是物种繁殖系统的最重要组分,处于强大的选择压力下,有很大的生态适应性。他们同时也受到较强的遗传控制,最具有区分和比较的意义。巴山冷杉的分布区包围着秦岭冷杉分布区,前者是一个正常的种群,后者却处在濒危的边缘。本研究在秦岭中段南坡和神农架北坡采集秦岭冷杉和巴山冷杉球果,测量和比较他们的球果和种子的结实特征;利用发芽试验,研究和分析两种冷杉在不同条件下的萌发特性;选择巴山冷杉群落设置样地和种子收集器,研究其种子雨并与秦岭冷杉的种子扩散特性进行比较;通过人工加速老化试验,探讨两种冷杉种子的劣变过程;利用播种试验和幼苗生长监测,研究秦岭冷杉野外幼苗的生态适应性。通过上述研究,首次揭示了种群命运截然不同的这两种冷杉在种实特性、更新特点等方面的异同,为了解秦巴山地优势针叶植被巴山冷杉林的更新策略、指导生产实践中科学选择母树和合理调拨种子提供了理论与实践依据。同时也为探讨秦岭冷杉濒危的繁殖原因、寻求该濒危种的复壮途径奠定了基础。本研究获得的主要结果有;1.两种冷杉种间、群体间、植株间结实特性差异明显,秦岭冷杉结实率(110.1个/株)明显低于巴山冷杉(201.6个/株)。秦岭冷杉核心区(秦岭地区)出种量较高,种子较大,种子的败育率高。秦岭冷杉结实量、成龄母树结实个体的比率随海拔升高而减少,低海拔的秦岭冷杉生殖生长好于高海拔处。巴山冷杉球果大小、单果出种量和种子质量在不同海拔高度以及同一海拔内都存在着显著差异,低海拔的巴山冷杉生殖生长高于低海拔。2.两种冷杉球果和种子的形态指标在群体间、个体间和个体内均有显著差异。巴山冷杉的种群间差异要大于秦岭冷杉。秦岭冷杉球果和种子形态特征变化约85%的变异来自地区内个体间和个体内,说明受遗传因素控制显著。低海拔处秦岭冷杉球果长、球果宽、球果重量、饱满度大于高海拔区,核心区的要好于边缘区,人工林优于天然林。巴山冷杉球果和种子形态特征在其分布区内存在垂直变异,海拔对巴山冷杉球果和种子形态特征的影响很大,高海拔区的种子形态好于低海拔。秦岭冷杉种子饱满度(25.7%)低于巴山冷杉(57.9%)。3.两种冷杉的种子雨扩散表现出一定的空间格局。巴山冷杉落雨过程中主要依靠重力和风力的共同作用进行扩散,对种子的后扩散和将来幼苗的萌发和更新格局产生一定的影响,在很大的程度上决定着种群未来的分布格局。秦岭冷杉种子较大,种子雨扩散不远,大部分种子都散布在母体周围,种子散布前期呈明显的聚集分布。在种子散布末期,散布量减少,种子因母树的分布而趋向于随机分布。秦岭冷杉种子雨散布距离(大部分集中在6m内)不及巴山冷杉远(88%的雨量集中在12m内)。4.两种冷杉种子之间的发芽率相差很大,秦岭冷杉发芽率(28%)远远低于巴山冷杉(80%)。同等条件下,巴山冷杉种子萌发率约三倍于秦岭冷杉种子。进一步说明同一属的两种植物,一种成为濒危物种,一种却有很大的种群,其中一个很重要的因素就是它们种子的生命力不一样。5.秦岭冷杉种子具浅休眠,在实验室最适环境中,经典的冷层积方法和适当的物理化学方法处理可以打破休眠,在萌发之前最好先浸泡种子3-5d,然后与湿沙1;3混合后,在1-5℃温度下进行层积处理,是提高种子的发芽率和发芽速率的最佳方法。核心区种子萌发率(38.1%)显著高于边缘区(13.8%),质量好于边缘区,表明核心区秦岭冷杉具有较优良的繁殖生物学特性。6.老化处理影响到两种冷杉种子的含水量和生活力。不同老化条件种子含水量反应不同。高温高湿条件会引发两种冷杉种子的快速老化,活力水平随着老化时间的延长而降低,40℃/100%RH处理6d种子基本丧失活力。7.天然生境下秦岭冷杉平均出苗率只有16.9%,不及实验室发芽率的一半(36%)。海拔、光照、苗床类型、埋藏深度和种子来源对秦岭冷杉的种子萌发、幼苗存活和幼苗生长率都有不同程度的影响,所以生产上秦岭冷杉的复壮一定要遵循适地适树(适种源)的原则。出苗率、幼苗保存率低可能是秦岭冷杉面临濒危的原因之一。更多还原

【Abstract】 Cones and seeds are the most important part of propagation system for conifers, and have great ecological adaptation under strong selection pressure. They can also form the basis for distinction and comparison between conifer species because they are mostly determined by genetic control. Abies fargesii is a common species currently under no conservation threats, while Abies chensiensis is an endangered species. The distribution area of A. fargesii is larger and encompasses the distribution of the less widespread A. chensiensis. Mature cones of the two firs were collected at the south slope of Qinling Mountain and the north slope of Shennongjia Mountain. The fruiting characteristics of cones and seeds were measured and comparatively analyzed. Accelerated seed aging processes and seed germination were studied under different experimental conditions. The spatial and temporal pattern of seed rain in Shennongjia was monitored through the setting of seed collectors in selected plots of A. fargesii communities, and was compared to that of A. chensiensis. Field experiments were conducted to determine seedling adaptations of A. chensiensis to different environmental conditions. Similarities and differences in fruiting characteristics and regeneration dynamics for these 2 firs with different population status were found for the first time based on above research. This provides the scientific basis to understand the regeneration strategies, wisely choose parent trees and allocate seeds and seedlings for A. fargesii. It also provides further understanding on the endangering causes for A. chensiensis and aids in the development of suitable restoration approaches. The major results are as follows.1. One-way ANOVA analysis showed fruiting characteristics had significant differences among populations and parent trees for both species. The number of cones per tree was 110.1 for A. chensiensis, which significantly lower than that of A. fargesii(201.6). For A. chensiensis in Qinling Mountain, the number of seeds per cone and the seed size were greater than that of most other specimens studies, but fewer seeds were fully developed per cone and showed very high abortion rates. With the increase of elevation, the ratio of fruiting trees to adult trees and the number of cones per tree were reduced, which indicated better reproduction for A. chensiensis at low elevations. Significant differences in cone size, the number of seeds per cones, and seed quality were found among differing elevations for A. fargesii, indicating better reproduction capabilities for A. fargesi at low elevations.2. The variance component analysis indicated the presence of significant differences of morphological traits of cones and seeds among populations, parent trees and cones for both fir species. For A. chensiensis, approximately 85% of the variation was attributable to differences between individual trees and within tree variation, providing strong evidence of substantial genetic control over traits. The mean values of traits for cones and seeds showed that plants distributed at low elevations were better than plants distributed at higher elevations, the core region was higher than the border area, the planted forest greater than the natural forest, showing that overall A. chensiensis reproduced better in the core region. For A. fargesii, the mean values of traits for cones and seeds changed along a vertical gradient, which showed that the high elevation was better than the low elevation. The different cone and seed traits between A. chensiensis populations was greater than those found between A. fargesii populations. The percentage of fully developed seeds in total seeds was 25.7% for A. chensiensis and 57.9% for A. fargesii.3. The seed rain of two firs showed different patterns that were affected by wind and seed weight. This dispersal pattern determines the seed germination, seedling regeneration and future distribution pattern of the populations. For A. chensiensis, the seed rain depended mainly on weight due to its comparatively larger size, and seed rain was concentrated in the distance of 6m far from the parent tree. 88% of the seed rain of A. fargesii populations was concentrated in the distance of 12m far from the parent tree. The seed rain pattern changed from a clump distribution pattern at the beginning of seed dispersal to a random pattern at the end of the dispersal period.4. The seed germination rates were significantly different between the 2 firs. The germination rate of A. fargesii (80 %) was 3 times that of A. chensiensis (28 %) under the same conditions. This suggests that seed viability may be an important causal factor in determining the abundance and consequently the conservation status differences between the two species.5. The seeds of A. chensiensis were found to undergo light dormancy. Some physical and chemical treatments were helpful to break dormancy of A. chensiensis besides cold stratification. Cold stratification under 1-5℃was the most successful method to increase germination rates and speed, after the seeds were soaked in water for 3-5 days and mixed with wet sand at a ratio of 1:3. Germination rates of seeds from the core region (38.1%) were significantly better than those from the border area (13.8 %) , which indicated that A. chensiensis in the core region had superior reproductive traits.6. High relative humidity and high temperature not only changed the moisture content of the seeds but also led to seed deterioration. The seeds of A. fargesii lost their vigor after storage at 40℃and 100% relative humidity for a period of 6 days.7. Seedling adaptation of A. chensiensis was revealed by field experiments under different conditions. The mean seedling emergence in field was only 16.9% and no morn than the half of that in lab. After one year, the seedling mortality was 57.6%. Seed germination and seedling survival and growth of A. chensiensis were affected by elevation, light conditions, seedbed material, sowing depth and seed provinces in differing degrees.更多还原