【作者】 薛瑶芹；

【导师】 张文辉；

【作者基本信息】 西北农林科技大学 ， 植物学， 2013， 博士

【摘要】 以秦岭地区的天然栓皮栎次生林为对象，在不同地区、不同生境设置固定样地，通过连续3年的样地监测、控制实验以及室内的植物内源激素分析，研究了栓皮栎无性繁殖幼苗种类以及对种群更新的作用、分析了萌生幼苗生长发育与环境因素和时间因素的关系，探讨了栓皮栎萌生苗发生与内源激素的关系，提出了利用栓皮栎无性繁殖基本规律的策略和对策，为秦岭地区栓皮栎次生林的持续经营提供了依据。主要研究结论如下：（1）秦岭地区的栓皮栎幼苗可以划分成实生苗、伐桩萌苗和干基萌苗：3种幼苗对栓皮栎次生林种群更新的贡献为伐桩萌苗>实生苗>干基萌苗，伐桩萌苗是最主要的幼苗，也是栓皮栎最主要的无性繁殖方式；实生苗有完整的、进展型年龄结构，伐桩萌苗各年龄的个体数呈间歇性波动；在1~5年生阶段，伐桩萌苗的基径、高度、地上生物量和叶面积均好于实生苗；伐桩萌苗竞争激烈，萌苗枯死率较高。伐桩萌苗生长快、个体多的特性，有利于其在快速恢复林地覆盖中发挥巨大作用；。（2）对择伐后不同时期的栓皮栎次生林中栓皮栎幼苗的调查发现，栓皮栎种群的繁殖方式受种群所处的恢复时期影响：伐桩萌苗密度为伐后5年>伐后10年>伐后20年>未砍伐林地，伐桩萌苗是择伐后林地中栓皮栎最主要的更新幼苗，其在种群更新的主导地位随着伐后时间的延长而下降，对种群恢复的贡献在林地择伐后初期更为重大；实生苗密度随着伐后时间的延长而上升，由于生长缓慢，对种群更新的作用在择伐后初期较小；干基萌苗没有竞争优势，对种群恢复的贡献较小。（3）生境条件对栓皮栎种群繁殖影响较大：在阴坡和阳坡，伐桩萌苗均是最主要的幼苗，坡向显著影响幼苗生长，伐桩萌苗和实生苗的基径均为阳坡>阴坡，高度为阴坡>阳坡；在林内，实生苗和伐桩萌苗重要值接近；在林窗和林缘中，伐桩萌苗的基面积和重要值均最大，在种群更新中占主要地位，林窗的存在对实生苗以及伐桩萌芽的产生及生长有利。（4）连续3年对栓皮栎皆伐迹地上伐桩萌发过程的跟踪调查和研究发现，80%的栓皮栎伐桩可以在伐后3年内一直产生和保存活萌苗，但伐桩存活率、萌苗数量和萌苗高度年增加量随伐后时间延长而不断下降；休眠季（12月）砍伐有利于伐桩萌苗发育生长，砍伐季节对萌苗生长的影响在伐后第2~3年消失；伐桩直径越大，其上萌苗数量越多，生长旺盛，伐桩高度仅在伐后第1年对萌苗数量和萌苗生长产生积极影响；较大直径（>15cm）和较高伐桩（>30cm）有利于萌苗生长发育。同一伐桩萌芽数量越多，竞争越激烈，萌苗生长越差，砍伐后应该及时抹芽以保证萌苗的生长。小生境对伐桩萌苗有有较大影响，林窗充足的光照环境有利于伐桩萌苗的产生和地上生物量累积，但林窗中萌苗枯死率高于林缘和林内。（5）不同胸径栓皮栎母树的主干基部环剥实验和连续2个生长季跟踪观测表明，直径在10cm~20cm的栓皮栎母树在环剥后容易产生干基萌苗，萌苗数量在2个生长季较为稳定，萌苗基径和高度也优于其他径级的母树；母树的直径（年龄）越大，产生干基萌苗的时间越晚，萌苗数量越少。（6）不同胸径母树的断根实验以及连续2个生长季的跟踪观测表明，断根处理能够促使胸径为10cm~20cm的栓皮栎母树的根系产生不定芽，但不定芽不能萌发成苗；秦岭地区的栓皮栎根系萌苗的发生是偶然的，其对栓皮栎种群更新的贡献有限。（7）高效液相色谱法对栓皮栎伐桩休眠芽和萌动芽中玉米素、生长素、赤霉素和脱落酸含量的测定表明，栓皮栎休眠芽的萌发与内源激素的种类及数量的关系十分密切：伐桩休眠芽中玉米素、赤霉素和生长素含量均远远小于萌动芽中的含量；休眠芽中脱落酸含量是萌动芽的2倍。赤霉素对休眠芽破除休眠有重要的促进作用。细胞分裂素类激素对伐桩休眠芽的始萌发也起着一定的促进作用。生长素对伐桩休眠芽的始萌发影响不大，脱落酸对休眠芽的萌发可能起着平衡和抑制作用。较高的赤霉素/脱落酸比值有利于伐桩休眠芽萌发。（8）在未来栓皮栎次生林经营中，应充分利用栓皮栎无性繁殖规律，促进种群持续发育和林地生态功能持续发挥：对栓皮栎次生林的择伐应选择在休眠季进行，且以伐桩高度大于30cm为标准，砍伐直径>15cm的栓皮栎个体，利用萌生苗速生特性，尽快恢复林地的生态防护功能；同时在择伐后又要尽量保护实生苗并适当增加实生苗数量以维持种群遗传多样性，促进林地持续发展；在更新不良的栓皮栎次生林中可以适当间伐生长不良的栓皮栎个体，开辟林窗，增加伐桩数量，促进栓皮栎种群更新；在栓皮栎次生林改造和经营中，可对胸径在10cm~20cm的间伐对象进行环剥，待其产生干基萌苗后再进行砍伐，有利于间伐林地的快速恢复。更多还原

【Abstract】 Natural Quercus variabilis forests in China have degraded because of over exploitingand cutting. Asexual propagation (sprouting) is an important reproduction mechanism insecondary Q. variabilis stands; however, limited information exists on the type of asexualreproduction, their positions and contributions to population recovery as well as factorsaffected sprouting in this species. The type of Q. variabilis sprouts, their positions in forestrestoration, time and space factors affected their contributions and growth were studied insecondary Q. variabilis forest, which is located in Qinling Mountains, through permanentplots survey and fixed experiments during2008~2010. Meanwhile, endogenous hormone indormant buds and sprouting buds of stump were detected to reveal the inner mechanism ofsprouting. The results were displayed below.(1) There were three different origins for Q. variabilis recruits in the research area,named as true seedling, stump sprout and stem base sprout, respectively, and stump sproutswere the main asexual recruits, and they contributed most to population restoration, trueseedlings were the second important recruits, and stem base sprouts just contributed a little topopulation restoration. Stump sprouts those were2~4years-old were abundant compared withother ages, while the age structure of true seedling was complete and the number of trueseedling declined with increasing age; base diameter, height, aboveground biomass and leafarea of stump sprouts were all higher than those of stem base sprouts and true seedlings; therewere drastic competition among stump sprouts, which was suggested by higher mortality rate.Stump sprouts were propitious to forestland recovering in short time because of their fastgrowth and abundant stems.(2) The relative importance of true seedlings and sprouts in different restoration stagesafter select logging for Q. variablilis population was evaluated in5,10and20yearspost-logging stands and unlogged stand. Sprouts especially stump sprouts were thepredominant recruitments in select-logged stands, while true seedlings were dominant inunlogged stand. The density of stump sprouts and sprouts number per stump, from high to low,were5years post-logging>10years post-logging>20years post-logging> unlogged stand, thedominant position of stump sprouts declined with increasing of post-logging age, the stumpsprouts contributed more to population recovery in the early stage after select-logging. True seedling’s contribution may be limited in the early stage after select-logging, but its densityincreased with prolong of population restoration time, meanwhile it benefits for forestlong-term development due to their ongoing age structure. Stem base sprouts, which wereshorter and smaller than other recruitments, were just observed in20years post-logging andcontrol plots and they contributed a little to population regeneration.(3) Slope aspect had no influence on population reproductive strategy, stump sproutswere the predominant recruits in both sunny slope and shady slope. But slope aspect didaffected the growth of recruits, the base diameter of stump sprouts and true seedlings in sunnyslope were greater than those in shady slope, and the height of these two kinds of recruitsdisplayed opposite trend. Q. variablilis took different reproductive strategies in understory,forest gap and forest edge: in understory, the positions of stump sprouts and true seedlingswere almost equal, but in forest gap and forest edge, stump sprouts occupied predominantposition implied by their largest base area and important value. Forest gap was a kind offriendly habitats which was beneficial for growth of sprouts and true seedlings compared withforest understory and forest edge. The number and growth of stem base sprouts were notinfluenced by slope aspect and micro-habitats, and there was no stem base sprout in forestgap.(4) Through surveying stump sprouting during3continuous years in clear-cutting Q.variabilis stand, we found that more than80%Q. variabilis stumps could keep live sproutsduring three years after cutting. All stumps sprouted in the first year after cutting, and stumpsurvival rate, sprout number, and sprout height growth declined with time after cutting.Stumps formed in December (dormant season) displayed greater sprouting ability than thosecut in growing season, but the effect of cutting season on sprouts growth disappeared in thesecond and third growing seasons after cutting. Stump diameter affected sprouting positivelythroughout the three years, while stump height influenced sprout number and sprout heightduring the first year, and the effect disappeared in the second and third years. So, larger basediameter (>15cm) and higher stump was beneficial for sprouting. It was essential toadjustment sprout number per stump in the early stage after cutting. After comparing thestump sprouts of understory, forest gap and forest edge, we found that forest gap was a kind offriendly habitat which was beneficial for stump sprouting and sprouts growth compared withforest understory and forest edge, although the mortality of stump sprouts in forest gap was alittle high.(5) The number and growth of stem base sprouts, which sprouted from mother trees indifferent DBH, were studied during two continuous growing seasons based on girdingexperiment. Q. variabilis mother trees in10cm~20cm DBH could form stem base sprouts easily after been girding, and the number of sprouts in these trees was stable, meanwhile, thesprout base diameter and height were both greater than those sprouts grew from other mothertrees during two years. However, sprouts mortality of these trees was lower than that of othermother trees. The relationship of sprouts number and mother tree DBH was negative, whichwas implied by sprouts number declining with increasing mother tree DBH（excpet first DBHclass）, as well as the sprouting time of large mother tree was later than that of small (smallDBH) mother tree.(6) Based on root-broken experiment that conducted in Q. variabilis mother trees withdifferent size, the broken root could form root sucker or not, as well as sprouts survival rateand growth were monitored during two continuous growing seasons. Adventitious buds weredetected in the broken root system of mother trees in10cm~20cm DBH, but these buds cannot develop to root sprouts. For Q. variabilis in Qinling Mountains, root sprouting was justaccidental phenomenon, and contribution of root sprouts to population regeneration waslimited.(7) The contents of four endogenous hormones, including ABA, IAA, GA3and Zeatin, insprouting buds and dormant buds of Q. variablilis stump were determined through highperformance liquid chromatography (HPLC). The sprouting of dormant bud was influencedintensely by the kinds and contents of endogenous hormones. The contents of IAA, GA3andZeatin in dormant bud were all far less than those in sprouting bud, while the content of ABAin dormant bud was as two times as that in sprouting bud. GA3played an important role inbreaking dormancy of dormant bud, and Zeatin promoted the initial sprouting of the dormantbud. IAA had little effect on dormant bud sprouting, while ABA inhibited and played abalancing act in sprouting. Higher value of GA3/ABA was better for dormant buds breakingdormancy.(8) During managing and conversion Q.variabilis secondary forest in the future, it wasbeneficial for stand fast recovery and polulation sustained development if applying asexualreproduction character reasonabley: cutting Q. variabilis with a larger base diameter (>15cm)at more than30cm high aboveground during the dormant season can maximize stumpsprouting, and the fast growth of stump sprouts can recover the ecological protection fuctionas soon as possible; meanwhile, after select cutting, keep the amount of true seedlings at areasonable level through protection and/or increasing the sowing density can increasepopulation gene diversity in cutting stand and be beneficial to true seedlings play a role inpopulation restoration in a long time; making girding to target Q.variabilis trees those were10cm~20cm in DBH first and then cut them after they sprouting, this method could helpcutting stand recover fastly; in the Q.variabilis secondary forest that was lack of recruits, cutting undergrowth Q. variablilis individuals appropriately to open forest gap, this measurecould promote population regeneration.更多还原