【作者】 王瑞波；

【导师】 何平；

【作者基本信息】 西南大学 ， 生态学， 2009， 博士

【摘要】 本研究的对象——南川百合(Lilium rosthornii Diels)及其对照种——泸定百合(Liliumsargentiae Wilson)属于百合科(Liliaceae)百合属(Lilium L.)多年生草本植物,均为中国特有植物,其药用和园艺观赏价值极高。南川百合分布于四川、重庆、湖北和贵州,主要生于山沟或溪边;泸定百合分布于四川、重庆、云南等地,主要生于山坡草丛或灌丛中。南川百合的分布区日益缩小,个体数量日渐稀少,已处于濒危状态。本研究通过对中国特有植物南川百合与其对照种泸定百合种群的空间分布格局、开花物候、花部综合特征、繁育系统、传粉生态学特征、种子萌发特性,以及水分胁迫、施肥与遮荫条件下的表型可塑性响应等方面的比较研究,探讨了南川百合在种群生态学、繁殖生态学、生理生态学等方面的生态对策及日渐稀少的原因。结果表明:1.采用分形理论与方差均值比率及几种聚集度指标对南川百合与泸定百合种群空间分布格局进行了分析,得到了基本一致的结果:南川百合种群均为集群分布,而泸定百合种群大体为集群分布,但趋向于随机或均匀分布;南川百合与泸定百合种群的分形维数均较小(远离2),说明其占据生态空间的能力都不大,体现其在群落中的劣势伴生地位,这样的地位使其易受群落中优势种的排挤;在2006年,南川百合种群的平均计盒维数(0.8100)比泸定百合种群(0.9435)小14.15%,平均关联维数(1.0867)比泸定百合(1.3297)小约18.27%,而其平均信息维数(0.3710)却比泸定百合种群(0.1852)大100.32%,这些意味着南川百合种群占据生态空间的能力比泸定百合弱,但其种群格局强度要比泸定百合大得多:在高温干旱的2006年,两种百合的平均计盒维数、信息维数及关联维数与2005年相比都有所减少,但南川百合种群平均计盒维数的减少比例(13.00%)约为泸定百合(9.04%)的1.44倍,平均信息维数的减少比例(22.71%)约为泸定百合(3.43%)的6.63倍,平均关联维数的减少比例(5.71%)约为泸定百合减少比例(0.23%)的24.83倍,这些数据表明,高温干旱天气对这两种百合的生长均有影响,泸定百合的抗热抗旱能力要高于南川百合,南川百合更易受高温干旱天气的伤害。此外,人为干扰也是影响南川百合种群大小不可忽视的因素。与泸定百合相比,南川百合是一个比较脆弱的物种,更容易导致濒危。2.通过南川百合的自然种群的开花物候、花部综合特征、繁育系统及传粉生态学特征等方面进行观察与分析可知:①南川百合开花时间为7～9月,单花花期一般为4～6d;个体开花持续时间6～26d,种群花期历时30d左右;自然种群开花进程为渐进式单峰曲线,属于“集中开花模式”,考虑到南川百合单个植株花少(花少数单生,多数2～9朵),因此这种开花模式有利其生殖成功。②南川百合开花过程柱头与花药的距离一般很近(甚至靠在一起),也有离得较远的,柱头的可授性先于花药散粉;其杂交指数为3或4,花粉-胚珠比约为2000～3880,结合人工套袋和授粉实验可以确定该种的繁育系统属于以异交为主,部分自交亲和,需要传粉者;而其对照种泸定百合的杂交指数等于4,花粉-胚珠比约为2400～4000,因此,南川百合的远交程度要低于泸定百合,而近交程度要高于泸定百合,这可能是其环境的选择压力及本身演化的结果,而自交则降低了其生殖失败的风险,但会降低后代的适应力;因其自身花粉很易落在自身柱头上,故花粉竞争可能是导致该种日渐稀少的主要的生殖生物学原因。③南川百合的传粉昆虫以大型的鳞翅目蝶类昆虫为主,常见的访花者有:碧凤蝶(Papilio bianor(Cramer))、玉带凤蝶指名亚种(Papilio polytes polytes Linnaeus)、美凤蝶大陆亚种(Papiliomemnon agenor Linnaeus)、檗黄粉蝶海南亚种(Eurema blanda hylama Corbet)、菜粉蝶东方亚种(Pieris rapae orientalis Oberthiir)等;传粉昆虫的访花行为与花蜜分泌具有较高的相关关系,这有利于其生殖成功,但传粉昆虫种类较少,体型较大,这不利于其生殖成功。3.通过对南川百合与其对照种泸定百合的种子萌发实验研究得知:在一定温度范围内,光照能延长南川百合与泸定百合种子萌发的开始时间,缩短种子萌发达到高峰与完全所需的时间,而避光则相反;光照下,南川百合种群种子的平均萌发率比泸定百合约低18.60%,虽在避光下比泸定百合高出4.66%,但比其在光照下低,这说明光照有利于这两种百合种子的萌发,而避光对泸定百合种子萌发有明显地抑制作用,对南川百合种子萌发也有一定影响,这些事实意味着南川百合比泸定百合耐荫的特点也反映在种子萌发上;南川百合与泸定百合种子萌发的温度范围为10～30℃,较为适宜的温度范围为15～25℃,其中泸定百合种子适宜萌发温度范围比南川百合宽,这说明泸定百合适应环境的能力比南川百合强;南川百合种子萌发在最佳光温组合(20℃24 h光照)时的萌发率(58.47%)比泸定百合种子在最佳光温组合时(15℃24 h光照)(99.17%)明显地低,这可能是南川百合日渐稀少的另一个重要原因。4.通过水分胁迫实验得知:①南川百合重度胁迫植株的叶面积在处理后期增加,叶片变薄,表现出不抗水分胁迫的特性;而泸定百合则相反,表现出抗水分胁迫的特性,且其茎与叶特征表现出比南川百合更高的表型可塑性。②在两个重要的光合作用适应性指标中,南川百合叶叶绿素a与叶绿素b的比率在处理后期,类胡萝卜素与叶绿素的比率在多数时段均随胁迫加重而下降,且变化幅度较大,表现出不抗水分胁迫的特性;在泸定百合却一直维持较高水平,变化幅度小,表现出抗水分胁迫的特性。③南川百合叶超氧化物歧化酶(SOD)活性与过氧化物酶(POD)活性可塑性比泸定百合小,且其POD活性在处理后期仍维持很高水平使之走向衰老,表现出较低的抵抗水分胁迫的能力。因此,与泸定百合相比,南川百合抵抗水分胁迫的能力较低。5.通过施肥与遮荫实验得知:①在不施肥或施肥条件下,南川百合的株高、冠幅、叶长、叶宽、叶面积等形态指标在重度遮荫中最高,其叶厚度最小,而泸定百合只有冠幅、叶长、叶面积在重度遮荫中最高,叶厚度在处理后期才最小;在相同程度的光照下,南川百合的多数形态指标表现为施肥高于不施肥,而泸定百合只有株高、叶宽、叶厚等表现为施肥高于不施肥;并且南川百合的形态表型可塑性比泸定百合高。②在两个重要的光合作用适应性指标中,南川百合与泸定百合叶叶绿素a与叶绿素b的比率以及类胡萝卜素与叶绿素的比率在不施肥或施肥条件下均在重度遮荫中表现出较低水平,但南川百合的可塑性高于泸定百合;南川百合与泸定百合叶叶绿素a与叶绿素b的比率在同样光照下均在施肥条件中表现出较低水平,而南川百合叶类胡萝卜素与叶绿素的比率在重度遮荫中下降,在泸定百合为上升,且在南川百合中以上两种指标的可塑性以及光合色素含量可塑性均高于泸定百合。③在不施肥条件下,南川百合叶过氧化氢酶(CAT)与超氧化物歧化酶(SOD)活性均随遮荫程度加重而升高,过氧化物酶(POD)活性仅在处理后期最高,而泸定百合CAT活性呈动态式消长变化,SOD活性随遮荫程度加重而下降,POD活性重度遮荫中在处理后期最高;施肥条件下,南川百合叶CAT活性、SOD活性与POD活性均在遮荫时较高,而泸定百合叶CAT活性在重度遮荫中最高,SOD活性是不遮荫中最高,POD活性是遮荫中最高;在同样光照下,南川百合叶POD活性虽在施肥中较低,但其CAT活性和SOD活性在施肥中最高,而施肥对泸定百合叶CAT活性、SOD活性与POD活性存在抑制现象;且在施肥与遮荫中有南川百合保护酶活性比泸定百合具有更高的可塑性。因此,南川百合比泸定百合更喜肥、耐荫,贫瘠的土壤与强光照环境对其生存不利。6.从研究结果看,南川百合日渐稀少的主要原因有:①过度采挖使种群难以在短期内恢复。②传粉昆虫种类少、体型大和花粉竞争导致种群内植株间近交频繁而结籽率低,影响生殖成功。③光照和温度是影响南川百合种子萌发的关键环境因子。温度的过高或过低直接导致自然环境中的种子萌发率很低,更新居群的实生苗少。④种群占据生态空间的能力弱,抗热抗旱能力不强。⑤南川百合不耐水分胁迫,也不耐瘠薄等,故其对生境的要求较严,适宜生长在比较湿润、肥沃、土层深厚的生境中。由此,可采取以下两个保护策略:第一、就地保护策略。在南川百合的主要分布地选择遗传多样性高、生境适宜、面积较大的种群建立自然保护小区进行就地保护,以抑制种群的减小,恢复该物种的种群数量,维持种群间一定的基因流水平,使该物种的许多小而分散的种群互相联系,以使该物种能够有足够大的群体来对抗环境的压力;同时,在保护其生境过程中要注意保护其传粉昆虫。第二、迁地保护策略。可以采取迁地保护的措施,将部分南川百合鳞茎或幼苗移植到比较湿润、肥沃、土层深厚的适宜生境中,通过人工更新的方法来保护和恢复这一日渐稀少的物种。更多还原

【Abstract】 Lilium rosthornii Diels(Liliaceae) and its congeneric species,Lilium sargentiae Wilson,are two perennial herbs endemic to China.Both species have great values in horticulture and medicine science.L.rosthornii distributes in Sichuan,Chongqing,Hubei,and Guizhou provinces,mainly occurs in valley or riverside.L.sargentiae distributed in Sichuan,Chongqing,Yunnan provinces,and so on,mainly occurs in grasses or shrubs on mountain slopes.The number of L.rosthornii is decreasing and its natural distribution is also shrinking gradually,which indicates this species is becoming an endangered plant.Population distribution patterns,flowering phenology,floral syndrome,breeding system, pollination ecology,and seed germination characteristics of L.rosthornii and L.sargentiae were comparatively studied,and phenotypic plasticity under water stress,fertilizing and shading experiments were also done in this paper.For L.rosthornii,the endangered reasons and ecological strategies from the views of population ecology,reproductive ecology,and physioecology of this species were dicussed.The results are as follows:1.According to the spatial pattern analysis in L.rosthornii and L.sargentiae by using the fractal theory and the mean/variance ratio and indexes of aggregation degree,the relatively consistent results were obtained.L.rosthornii are all clumped distribution,however,the majority of L. sargentiae populations is clumped distribution,but they are tending to random and regular distribution.The populations of both species had low fractal dimension(far from 2),suggesting that their spatial occupation degrees were low and that they functioned as accompaniment populations in the communities.This status makes it easily supplanted by the dominant species.In 2006,in L. rosthornii populations,the mean box-counting dimension decreased by 14.15%and the mean correlation dimension decreased by 18.27%,while the mean information dimension increased by 100.32%,suggesting its lower spatial occupation degrees but a higher scale variation degrees,as compared with those of L.sargentiae populations.As compared with in 2005,populations of both species had lower mean box-counting dimensions,information dimensions,and correlation dimensions in 2006.This may be due to the particularly dry climate they experienced in 2006.The percentage by which the mean box-counting dimension decreased was 1.44 times higher in L. rosthornii(13.00%) than in L.sargentiae populations(9.04%).On the other hand,the percentage by which mean information dimension and correlation dimension decreased was much higher in L. rosthornii(22.71%and 5.71%,respectively) than in L.sargentiae populations(3.43%and 0.23%, respectively).These data indicated that the growth of both species was influenced by the hot and dry conditions and that L.sargentiae had stronger resistance to high temperature and drought as compared to L.rosthornii.Moreover,man-made disturbance is also a significant factor which affects the size of L.rosthornii populations.It can be concluded that L.rosthornii,compared with L. sargentiae,is a species more vulnerable to the exceptional climatic events.2.The studies on flowering phenology,floral syndrome,breeding system,and pollination ecology of L.rosthornii indicated that:(1) The flowering time of L.rosthornii was from July to September,anthesis of a single flower lasted from 4 to 6 days.The flowering span of the individuals and population was about 6 to 26 days,30 days respectively.The flowering process of L.rosthornii in wild populations shows a gradually single peak curve,belong to the so-called“Mass-flowering”pattern.As there were few flowers with individuals(single flower in minority but 2 to 9 flowers in majority with one individual),this pattern may be regarded as an adaptive strategy to ensure its reproductive success.(2) The distance from stigma to anthers usually was very short(sometimes connect each other).The stigma receptivity took precedence of dehiscence of anther of a flower.The out crossing index(OCI) of L.rosthornii was 3 or 4.The pollen-ovule ratio(P/O) was about 2000 to 3800.Combining with the results of emasculation,bagging,and artificial pollination studies,the breeding system of this species was mainly determined to be out-crossing,sometimes self-compatible,need pollinators.The out crossing index(OCI) of L.sargentiae was 4.The pollen-ovule ratio(P/O) was about 2400 to 4000.Thus the degree of outbreeding of L.rosthornii was lower than that of L.sargentiae,while the degree of inbreeding of the former was higher than the latter.This probably was due to environmental selection pressure and self-evolutionary,i.e., self-crossing reduced the risk of reproductive failure,which decreased the adaptability of the offspring.The pollen grains of the flower fell on its own stigma very easily.Pollen competition may be the major factor leading to the endangered status of L.rosthornii.(3) Large butterflies in Lepidoptera were the dominant pollinators of L.rosthornii,e.g.,Papilio bianor(Cramer),Papilio polytes polytes Linnaeus,Papilio memnon agenor Linnaeus,Eurema blanda hylama Corbet,Pieris rapae orientalis Oberth(u|¨)r and so on.There were relatively high correlation between visiting behaviors of pollinators and nectar secretion,which was helpful for the reproductive success of the species.But there were a few species of pollinators with bigger bodies,which was disadvantageous to reproductive success.3.The seeds germination of L.rosthornii and L.sargentiae showed that:In certain temperature extent,light illumination delayed the time of the seeds of both L.rosthornii and L.sargentiae starting to germinate,and shortened the time seeds germination reached the peak.Under light illumination,the mean seed germination rate of L.rosthornii was 18.60%lower than that of L. sargentiae,while it was 4.55%higher than that of L.sargentiae in the absence of light illumination. This showed that sunlight was beneficial for the seeds germination of the two plants,and the absence of sunlight had distinct inhibiting effect on the seeds germination of L.sargentiae,it also had some influences on the seeds germination of L.rosthornii.All these facts mean that shade tolerance of L. rosthornii stronger than that of L.sargentiae could also be reflected by the seeds germination.The temperature range for the seeds germination of L.rosthornii and L.sargentiae was 10～30℃,and the suitable range was 15～25℃.Besides,the appropriate temperature range for the seeds germination of L.sargentiae was wider than that of L.rosthornii,which showed that L.sargentiae had stronger adaptation ability for environment than L.rosthornii.The seed germination rate of L. rosthornii(58.47%) under the best combination of temperature and sunlight(20℃,24 h light illumination) was obviously lower than that of L.sargentiae(99.17%) under the best combination of temperature and light(15℃,24 h light illumination),this may be another reason why L.rosthornii was becoming more and more scarce.4.The experiment of response to water stress displays that:①heavily stressed plants of L.rosthornii,their leaf area is increased in the later process period,leaves are getting thinner,and they do not show the characteristics of anti-water stress;however,the L.sargentiae is the opposite, and shows the characteristics of anti-water stress.The features displayed in caudex and leaf of L. sargentiae show even higher phenotypic plasticity index compared to L.rosthornii.②In two important indicators of photosynthesis adaptation,the ratio of Chlorophyll a and Chlorophyll b of L. rosthornii is decreased when the stress is increased during the later process period,and the ratio of Carotenoid and Chlorophyll is also decreased when the stress is increased during most of the time, and these two changes experience a larger range difference an do not show the characteristics of anti-water stress;however,the ratios of L.sargentiae keep in constant high value with a little change, and show the characteristics of anti-water stress.③The plasticity index(PI) of activities of SOD and POD of L.rosthornii is less than the PI of activity of L.sargentiae,and its POD activity maintains at high level during the later process period following by decrepitude,and show lower ability of performing anti-water stress.Thus,compared with L.sargentiae,L.rosthornii’s ability of performing anti-water stress is lower. 5.According to the experiment of fertilizing and shading treatments,it can be show that①In either fertilizing or non-fertilizing condition,the morphological indicators of plant height,crown diameter,leaf length,leaf width and leaf area of L.rosthornii are the highest in heavy shading,and its leaf thickness is the smallest,however,only crown diameter,leaf length and leaf area of L. sargentiae are the highest in heavy shading,and the leaf thickness is the smallest only during the later process period.With the same sunlight condition,the most morphological indicators of L. rosthornii in the fertilizing condition are larger than the non-fertilizing condition,but only plant height,leaf width and leaf thickness of L.sargentiae are larger in the fertilizing condition compared with the non-fertilizing condition.The PI of architectural traits of L.rosthornii is larger than that of L.sargentiae.②in two important indicators of photosynthesis adaptation,the ratio of Chlorophyll a and Chlorophyll b,and the ratio of Carotenoid and Chlorophyll for both L.rosthornii and L. sargentiae with either fertilizing or non-fertilizing condition,represent a lower value in heavy shading condition,but plasticity index,PI of L.rosthornii is higher than L.sargentiae.The ratio of Chlorophyll a and Chlorophyll b for both L rosthornii and L.sargentiae with the same sunlight condition,represent a lower value in fertilizing condition.The ratio of Carotenoid and Chlorophyll of L.rosthornii is decreased under the heavy shading condition,while the ratio is increased for L. sargentiae.The PI of the two above indicators and photosynthetic pigments of L.rosthornii is larger than L.sargentiae.③In non-fertilizing condition,CAT and SOD activity of L.rosthornii are increased when the degree of shading is increased,POD activity is the highest only during the later process period,but CAT activity of L.sargentiae shows dynamic changes in the growth and decline, SOD activity is decreased when the degree of shading is increased,POD activity with heavy shading is the highest during the later process period.In fertilizing condition,CAT,SOD and POD activity of L.rosthornii all reach the highest with shading condition,but CAT activity of L.sargentiae is only highest with the heavy shading condition,SOD activity reaches the highest with non-shading condition,POD activity is the highest under the shading condition.In the same sunlight condition, although the POD activity of L.rosthornii is lower under the fertilizing condition,the CAT and SOD activity are the highest under the same condition,and fertilizing has a inhibited effect on the CAT, SOD and POD activity of L.sargentiae.In the fertilizing and shading conditions,the protective enzymes activities of L.rosthornii has larger PI value than the protective enzymes activities of L. sargentiae.Therefore,L.rosthornii can easily adapt with fertilizing and shading habitats,and barren land and strong sunlight are harmful to their survival.6.According to the experiment results,the reasons that L.rosthornii is becoming increasingly scarced are:①Over-excavation by mankind make it difficult to restore this species in a short time.②The limited species number of pollinators,bigger bodies and pollen competition lead to the high incidence of inbreed seed rate between plant populations and reduce the probability of seeding rate, influencing its reproductive success.③Light and temperature are the two key environmental factors in affecting seed germination of L.rosthornii.Temperature which is too high or too low will directly lead to a low seed germination in natural environment,and a small regenerated seedling population.④Its populations have lower spatial occupation degrees and weaker resistance to high temperature and drought.⑤L.rosthornii do not show the characteristics of anti-water stress and the tolerance of barren soil,so it requires strict habitat,and are adaptable to grow up in habitat with relatively moist,fertile and deep soil.Based on the information available for L.rosthornii,two alternative conservation strategies are proposed.The first would consist of an in situ conservation plan that defines areas free from significant disruption for at least the genetically most diverse populations.This would guarantee the maintenance of most of the species’ genetic variation.By that,the decreased trend of population can be inhibited,the individual number of populations for this species can be restored and the certain gene flow level can be maintained.So many small and dispersed populations of the species can be associated so that the species can have large populations to resist the pressure of the environment.At the same time,it is necessary to pay attention to protect pollinators of L.rosthornii during the protection process of ecological environment.The second management strategy would be a program of ex situ conservation.The program of ex situ conservation can be taken.The way to protect and restore this suffered populations of species can be implemented through the method of artificial regeneration.更多还原