【作者】 周云娟；

【导师】 鲁琳；

【作者基本信息】 四川农业大学 ， 园林植物与观赏园艺， 2011， 硕士

【摘要】 桫椤属于我国二级保护植物,也是我国珍稀濒危植物之一,被世界自然保护联盟(IUCN)列入国际濒危物种保护名录。国内分布地区主要有四川、云南、贵州、广东、广西、福建等省,但由于缺乏完善的保护机制,大量桫椤都遭到了不同程度的破坏。加上生态环境的恶化,使得桫椤的繁殖和生存越来越困难,缺乏更新资源,年龄结构趋于老龄化,数量也就越来越少。因此,对桫椤的结构和种群动态研究,探讨其现状及动态,对有效保护桫椤种群、优化保护措施具有重要意义。种群的结构与动态变化一直是植物生态学研究的主要内容和热点问题之一,研究方法比较成熟,且在濒危植物方面取得了一定成绩。本文主要从群落生态学的角度出发,通过生存分析、生态位、空间格局及种间联结性分析研究探讨了荣县金花乡桫椤自然保护区内不同地段桫椤种群的年龄结构和动态特征。得到如下结果：1、选用茎干高度作为衡量桫椤大小的指标,建立年龄结构。6个样地总体呈现两种类型,Q1,Q2,Q4为增长型,Q3,Q5,Q6为衰退型。不同地段的样地都表现出幼苗数量较大,但成活率极低,中期植株数量少,大型植株数量多的特征。2、运用空间代替时间的方法,以高度级为基础编制的静态生命表显示第2龄级和第13龄级有着较高的死亡率,表明自然环境对桫椤幼苗的生长很不利,这可能是造成桫椤濒危的主要原因。3、桫椤种群的存活曲线兼具Deevey—Ⅰ型与Deevey—Ⅲ型曲线的特点。种群在前期存活数急剧下降,死亡率极高。第3龄级到第10龄级之间稍平缓,进入第12龄级,死亡率升高,13龄级达到最高,存活曲线斜率略微增加。4、桫椤种群的存活率总体上随龄级的增加呈下降趋势,与该龄级出现的高死亡率相对应。相应的积累死亡率总体上呈上升趋势,且曲线上升幅度表现为幼苗期大于后面的龄级。种群死亡密度f(t(?))函数曲线呈现出整体下降趋势,具体表现为前期下降幅度较大,后期较为平缓的特点。5、通过对生态位重要值的计算,结果显示乔木层生态位重要值降序排列为：桫椤>5(Eurya spp.)>薄果猴欢喜>杜茎山>川柯；草本层生态位重要值降序排列为：桫椤>17(pteris spp.)>密脉木>楼梯草>山姜>半边铁角蕨>华南紫萁>狭叶巢蕨>边缘鳞盖蕨>黑足鳞毛蕨。桫椤在乔木层和草本层都占据了重要地位。6、定量分析生态位宽度,结果表明乔木层中桫椤、5(Eurya spp.)、薄果猴欢喜、川柯有较大的生态位宽度,其Levins和Hurlbert生态位宽度值分别为5.9872、5.9685、5.8518、5.6517和0.9974、0.9937、0.9704、0.9303；草本层17 (Pteris spp.)、楼梯草、桫椤、山姜、华南紫萁有较大生态位宽度,其Levins和Hurlbert生态位宽度值分别为5.8564、5.7740、5.5767、5.6687、5.5921和0.9713、0.9548、0.9153、0.9337、0.9184。这说明桫椤在群落中占据了主要地位,对资源利用程度较高,为该群落的优势种。7、通过生态位相似性比例分析,桫椤与生态位宽度值大的物种间的生态位相似性比例值大,而与生态位宽度值小的物种间的生态位相似性比例值小。表明桫椤与群落中生态位宽度较大的物种利用资源的相似程度较大,易于与其形成混交林。8、桫椤与生态位宽度值较大的物种间的生态位重叠值相对较大,表明桫椤与这些物种的生活型相对较为接近,利用资源的能力相对较为相似。9、运用几个聚集度指标测定出6个桫椤种群的空间分布格局均为聚集分布,其聚集强度由高到低排序为：Q2>Ql>Q6>Q5>Q4>Q3。通过计盒维数和信息维数分析,得到样地Q2的桫椤种群的空间占据程度在6个样地中最高,其建群和优势地位最明显,其空间分布格局强度随尺度变化的程度最明显,个体分布聚集程度高。10、Spearman秩相关分析结果表明大多数种群之间呈正联结,种对数占65%。桫椤与喜马拉雅珊瑚、边缘鳞盖蕨、(15)、(25)、(3)、薄叶卷柏、华南紫萁、(18)、水东哥之间有极显著的正联结,说明桫椤与这几个物种对环境的需求相似,并且在长期的适应中相互依存。更多还原

【Abstract】 As one of the Rare & endangered species, Alsophlia spinulosa is national second-class protective plant, and was listed in the international endangered species protection list by IUCN. In China, its main distribution regions include SiChuan, YuNan, GuiZhou, GuangDong, GuangXi, FuJian, and so on. Due to deficiency of a thorough protection mechanism, a large number of A. spinulosa had suffered different extent destroy. Meanwhile, the ecological environment is getting worse, and the propagation & survival turned out to be more difficult, thus, the number of Alsophlia spinulosa is getting less and less. It seems so urgently to get down to research on population structure and dynamics, and discuss its current situation and trend of A. spinulosa.The study on population structure and dynamics is one of the main points and hot issues in phytoecology research area. In this paper, following the principle of genecology, and with the help of Survival analysis, ecological niche, spatial pattern and interspecific association analysis, the population structure and dynamics of A. spinulosa in RongXian JinHua Natural Preservation area was studied. The results showed that:1、Choosing stem height as a measure of age to establish the age structure, all 6 sample plots presented two types in general. Increasing type includes Q1、Q2、Q4 and recession type includes Q3、Q5、Q6. Each sample plot had a large amount of seeding, but low survival rate.2、Applying the method of space instead of time, compiling the static life table which was based on age level. The data showed the 2ed age level & the 13th level had higher mortality. It means the natural environment was not beneficial for A. spinulosa seedings’growth.3、The survival curve of Alsophlia spinulosa population had both characteristic of type Deevey—Ⅰ& Deevey—Ⅲ. The number of survival individual decreased sharply in the earlier stage with a high mortality, and tend to be gently from the 3ed age level to the 10th age level. When got into the 12th age level, the mortality rate increased, and reached the peak at the 13th age level.4、The downtrend of survival rate relative to high mortality at each age level. Meanwhile the accumulation mortality display increasing trend in general, and the rising amplitude showed stage of seeding larger than the other. And the death density display decreasing trend, the decrease amplitude showed large in the early stage, gentle in the later.5、Based on the niche value analysis, the results showed A. spinulosa occupied an important position in both tree layer and herb layer. The niche values in drop order was:Alsophila spinulosa>5(Eurya spp.)>Sloanea leptocarpa>Maesa japonica> Lithocarpus fangii. In the herb layer was:Alsophila spinulosa> 17(Pteris spp.)> Elatostema involucratum> Myrioneuron faberi> Alpinia japonica> Asplenium unilaterale>Osmunda Vachellii>Neottopteris simonsiana>Microlepia marginata> Dryopteris fuscipes.6、The niche breadth was analysised quantitatively in this article, the Levins & Hurlbert niche breadth shows the results were in agreement. In the tree layer, Alsophila spinulosa、5(Eurya spp.)、Sloanea leptocarpa、Maesa japonica、Lithocarpus fangii had bigger niche breadth, their Levins & Hurlbert niche breadth are 5.9872、5.9685、5.8518、5.6517and 0.9974、0.9937、0.9704、0.9303. In the herb layer,17(Pteris spp.)、Elatostema involucratum、Alsophila spinulosa、Alpinia japonica、Osmunda Vachellii had bigger niche breadth, their Levins & Hurlbert niche breadth are 5.8564、5.7740、5.5767、5.6687、5.5921 and 0.9713、0.9548、0.9153、0.9337、0.9184. So A. spinulosa was the dominant species in the community which took an important position, and high degree of resource utilization.7、Trough the niche similarity analysis, we can see Alsophila spinulosa had higher niche similarity with the species that had bigger niche breadth, nevertheless had lower niche similarity with the smaller ones. Thus, A. spinulosa’s resource utilization was more similar to the ones’had bigger niche breadth, and was likely to form mixed forest.8、Alsophila spinulosa had high Niche overlap with species which had bigger niche breadth, and was close to their biotype, similar with their ability on resource utilization.9、Using 4 aggregation index to find out that 6 sample plots’ spatial distribution pattern was aggregated distribution, and the intensity was:Q2>Q1>Q6> Q5>Q4>Q3. Meanwhile the Box Dimensions & Information Dimensions showed A.spinulosa population in Q2 had the highest spatial occupation capacity, its colonizing & dominant status was obvious.10、The result of Spearman Rank Correlation Analysis showed 65% of the populations presented positive association. A.spinulosa had extremely significant positive association with Aucuba himalaica、Microlepia marginata、(15)、(25)、(3)、Selaginella delicatula、Osmunda Vachellii、(18)、Saurauia tristyla. It meant A.spinulosa had the similar request of environment with these species, and got interdependent in the long-term adaptation.更多还原