【作者】 郭有燕；

【导师】 张文辉；

【作者基本信息】 西北农林科技大学 ， 森林培育， 2013， 博士

【摘要】 本文以陕北黄土丘陵区文冠果天然种群为研究对象，通过典型样地调查和控制试验，对文冠果种群不同生境条件下的繁殖方式、繁殖特征、繁殖对策、年龄结构、空间分布格局进行了系统研究，分析了文冠果种群在不同生境条件下的有性生殖和无性繁殖能力及适应策略；对陕北黄土丘陵区文冠果种群天然类型进行了划分，初选了速生、高产的优良单株；分析了种子大小与耐旱性的关系；为文冠果天然林保护和资源培育提供了依据。主要研究结果如下：（1）不同生境文冠果种群有性生殖生态研究表明：不同坡向文冠果天然种群均具有有性生殖能力，阳坡生境的文冠果单株开花量、结实量相对半阳坡和半阴坡生境均较大；文冠果结实主要集中在树冠的上部和中部，下部较少；阳坡、半阳坡和半阴坡3种生境文冠果种子形成1年生幼苗的概率低，文冠果实生幼苗数量较少，随着幼苗年龄的增加，数量进一步减少，依靠实生苗不足以实现文冠果种群更新；阳坡生境有利于实生苗定居发育，幼苗高度、基径生长和生物量积累均优于半阳坡和半阴坡；环境因素对文冠果有性生殖有影响，光照与单株产种量、幼苗生物量积累呈正相关，而土壤水分与实生苗数量呈负相关。（2）文冠果种群无性繁殖研究表明：无性繁殖方式主要有根基萌苗、根系萌苗和伐桩萌苗，其中根基萌苗对文冠果种群更新贡献较大。文冠果3种无性幼苗的生长均表现为阳坡＞半阳坡＞半阴坡，并且3个生境，文冠果无性幼苗生长均表现为伐桩萌苗＞根基萌苗＞根系萌苗；半阳坡生境文冠果种群无性繁殖能力最大，而半阴坡生境最小；随着伐桩高度的增加，萌苗数量增加，萌苗生长旺盛，当伐桩高度达到10.1-15cm时，萌苗数量达到最大值；伐桩直径与萌苗数量、萌苗生长量呈正相关；断根直径越大，萌苗数量越多，并且基径、冠幅与断根直径呈显著的正相关；萌苗高度则随着断根直径的增大先增加后减少；每桩或每断根根系上萌苗数量过多时不利于萌苗的生长。（3）文冠果种群在各坡向均有有性生殖和无性繁殖，种群在各坡向存在两种繁殖方式的权衡。在阳坡、半阴坡生境，文冠果实生幼苗数量与无性幼苗数量比值大于1，说明种群主要以有性生殖为主。在半阳坡生境，实生幼苗数量与无性幼苗数量的比值小于1，说明种群主要以无性繁殖为主。两种繁殖的瓶颈期在实生苗的种子-幼苗阶段和无性苗的幼树-成株阶段；在相同生境条件下，文冠果幼苗生长状况均表现为无性苗＞实生苗，在3个生境生长表现为阳坡＞半阳坡＞半阴坡；陕北黄土丘陵区文冠果种群在新生境定居下来的过程中，首先以实生苗入侵；当水分、光照、养分较好时，文冠果又以无性繁殖方式迅速占领空间，繁衍后代。（4）通过对陕北黄土丘陵区文冠果种群年龄结构、空间分布格局进行研究表明：陕北黄土丘陵区文冠果种群年龄结构呈进展型，幼龄个体数多，中老龄个体数少；文冠果种群在Ⅱ龄级死亡率较高，随着龄级的增加，死亡率降低，种群在Ⅴ龄级、Ⅵ龄级再次出现了死亡高峰；该地区文冠果种群存活曲线呈DeeveyⅢ型；种群在空间分布格局上总体呈聚集分布，半阳坡生境文冠果种群聚集强度较大，随着龄级的增加，聚集强度逐渐降低，逐渐趋于随机分布。（5）通过对陕北黄土丘陵区文冠果种群天然类型划分和优良单株选择，依据生长性状和结实性状将文冠果天然类型划分为4类：低产乔木型、低产灌木型、高产乔木型和高产灌木型，其中，低产乔木型和低产灌木型在该区域文冠果种群中所占的比例较大。根据选优的标准，通过因子分析法，在该区域共选出30株速生高产的优良单株，其中，任家台9株，交道坡7株，仁台村6株，公路山8株。（6）种子大小和文冠果耐旱性关系的研究表明：随着水势的降低，发芽率逐渐降低。-0.6Mpa处理下种子发芽率与-0.2Mpa处理下的发芽率相比显著降低；在各处理中，大种子发芽比例最高，且最早开始发芽；随着水分胁迫的增加，MDA、Pro、SOD、POD、CAT含量均增加，水分是种子萌发的关键因子；通过发芽率、渗透调节物质和抗氧化物酶活性的测定表明，大种子表现出更大的耐旱性。更多还原

【Abstract】 In this paper, the Xanthoceras sorbifolia natural populations were taken as the researchobject, and propagation mode, propagation characteristic, propagation strategy, age structure,spatial distribution pattern of them were studied in different habitat in hill loess plateau innorth shaanxi by research of typical plot and controlled experiment, in order to analyze thesexual, asexual propagation capacity and propagation strategy, partition natural type andselect the fine tree, as well as analyze seed size and plant drought resistance, thus, providingbasis for natural protect and resources cultivation. The main results were as follows:（1）Through study the sexual propagation ecology of Xanthoceras sorbifolia indifferent habitat, it was showed that the sexual propagation process was completed indifferent slope. Sunny slope had biggest flowering and fruiting capacity compared withsemi-sunny slope and semi-shady slope. The fruits were mainly distributed in the upper andmiddle canopy. The probability of seed conversion to one-year-old seedling was low, thenumber of seedlings were fewer in three slopes. With the grow-up of seedling age, seedlingnumber reduced gradually. The number of seedling may not realize completely sustainedregeneration of the population. Sunny slope provided favorable condition for seedlingestablishment. Seedling of sunny slope height, base diameter growth and biomassaccumulation were superior to semi-sunny slope and semi-shady slope. Light was positivecorrelation to seed number per Xanthoceras sorbifolia individual and seedling biomassaccumulation. Soil water was negative correlation to seedling number.（2） Through study the asexual propagation of Xanthoceras sorbifolia population, it wasshowed that in this region exists as three modes: sprouts from main root, sprouts from rootand sprouts from stump. Sprouts from main root have bigger contribution for populationregeneration. The asexual remets growth showed that sunny slope＞semi-sunny slope＞semi-shady slope. The asexual remets growth showed that stump sprouts＞main root sprouts＞root sprout in three slopes. The asexual propagation ability was the biggest in semi-sunny slope, and the smallest in semi-shady slope. With increase of stump height, sprout numberand growth increased. When the stump height reached10.1-15cm, sprout number was thebiggest. The stump diameter was positive correlation to sprouts number and growth. Cuttingroot diameter had the positive correlation with sprouts number, base diameter and crown.Sprouts height increased with the diameter increasing, when cutting root diameter exceed thevalue, sprouts height decreased gradually. When sprouts number of per stump or root exceedthe value, it was disadvantageous to sprouts growth.（3）Xanthoceras sorbifolia population had the sexual and asexual propagation in3slopes,but it exists a balance between two propagation modes. The ratio of seedling and asexualremets was more than1in sunny slope and semi-shady slope. It showed that Xanthocerassorbifolia population main propagation mode was sexual propagation in two habitats. Insemi-sunny slope, the ratio of seedling and asexual remets was less than1. It showed thatXanthoceras sorbifolia population main propagation mode was asexual propagation in thishabitat. Sexual propagation bottleneck stage appeared from seed to seedling. However,asexual propagation bottleneck stage appeared from seedling to remets. In the same habitat,seedling growth showed that asexual remets＞seedling. The same origin seedling growthshowed that sunny slope＞semi-sunny slope＞semi-shady slope. The way of Xanthocerassorbifolia invasion by seed was to settle in new habitat, and then occupied the space rapidlyby asexual propagation.（4）According to the research of the age structure and the spatial distribution ofXanthoceras sorbifolia population, the result showed that the age structure of Xanthocerassorbifolia population was progressive, the number of young growth individuals was morethan these of half-mature and mature individuals. The life tables present that the mortalityrates were highest at age class Ⅱ, decreased with age increasing, and gone up again at ageclass Ⅴ and Ⅵ owing to plant decrepitude. The survival curve belongs to the type of DeeveyⅢ, and the spatial distribution of population was aggregative pattern generally, theaggregative intensity was decreased and tended to a random distribution along with ageincreasing，was greater in semi-sunny slope.（5）According to growth and fruiting characteristic, the natural type of Xanthocerassorbifolia population may be divided into low yield tree patterns, low yield shrub patterns,high yield tree patterns, low yield shrub patterns in the hill loess plateau in north Shannxi.The ratio of low yield tree and shrub pattern was more in this region. According to thestandard of plus tree selection,30plus trees were selected in this region by factor analysis.Fu-county was16,9in Renjiatai,7in Jiaodao slope, respectively. Yan’an city was14,6inRetai village,8in Gonglu mountain, respectively. （6）The effects of seed size and Xanthoceras sorbifolia drought tolerance were studied.The results showed that germination percentage decreased gradually in all seeds withdecreasing water potential. The reduction was more significant under-0.6MPa treatment thanunder the-0.2MPa treatment in all seeds. The germination percentage of the big seeds was thehighest in all treatments and had the earliest initiated germination compared with those of themedium and small seeds. Lipid peroxidation (malondialdehyde), osmotic substances (freeproline), and antioxidative enzymes (peroxidase, superoxide dismutase, and catalase)increased in all seeds with increasing water stress. The values of all parameters indicated thatwater was a critical factor in Xanthoceras sorbifolia seed germination, and the big seedsdisplayed increased tolerance to water stress as measured by germination percentage,osmoregulatory substance, and antioxidant enzymatic activities.更多还原