【作者】 宋萍；

【导师】 洪伟； 吴承祯；

【作者基本信息】 福建农林大学 ， 生态学， 2004， 硕士

【摘要】 濒危物种的研究和保护是当前世界研究热点问题——生物多样性的重要内容之一。桫椤为我国一级重点濒危保护植物，它是白垩纪末，第三纪早期冰川的孑遗植物，是世界上最古老的活化石和目前仅存的木本蕨类植物之一，它对研究古气候与植物起源、进化和植物地理区系具有重要价值：同时桫椤还具有极高的园艺观赏价值、药用价值及其它多种用途，因此开展桫椤的生态学研究对于桫椤濒危机制的探索，有效保护桫椤种群、保护生物多样性、以及桫椤资源的开发利用等都具有重要意义。 本研究应用数量统计学方法对福建瓜溪桫椤自然保护区不同地段的桫椤种群生态学与生态场特性进行了分析讨论，包括种群结构与动态、种群格局的分形特征、种群生命过程分析、个体地上部生态场特征、个体地上部生态场梯度及其变化规律、种群地上部生态场研究等。研究结果如下： (1) 运用“空间序列代替时间变化”的方法，选用茎干高度作为个体大小的指标。7个地段的桫椤种群大小结构存在增长型、稳定型、成熟型和衰退型四种类型。 不同地段的桫椤种群表现为不同的空间分布格局类型，集群或随机分布，集群分布一般发生在幼苗多、成体少的增长型的种群中，随机分布则发生在以成体为主、幼苗相对较少的稳定或衰退型种群中；桫椤种群具有一定的扩散性，在其生长过程中，分布格局从集群型向随机型转变，幼苗呈集群分布，而大株呈随机分布；不同取样尺度下，桫椤种群格局聚集度不同，扩散型指标一般随取样尺度的增大而减小，取样尺度对桫椤种群空间分布格局的测定存在一定影响。 (2) 8个地段的桫椤种群在空间占据、格局强度和个体空间相关性等方面存在着不同的尺度变化和分形特征，种群格局计盒维数值在0.3132～1.1189之间，大小次序为Q3＞Q6＞Q7＞Q1＞Q2＞Q4＞Q5＞Q8，信息维数在0.3031～1.078之间，大小次序为Q3＞Q7＞Q6＞Q1＞Q2＞Q5＞Q8＞Q4，关联维数在0.7450～1.1453之间，大小次序为Q3＞Q6＞Q8＞Q1＞Q5＞Q7＞Q2＞Q4；分形维数谱显示，地段Q1、Q2、Q3、Q6和Q7的桫椤种群空间结构特征相似，地段Q4、Q5与Q8的种群相似。 (3) 以高度级为基础编制的桫椤种群特定时间生命表显示，桫椤幼苗个体相对丰富，种群结构为前期增长、后期稳定的类型。桫椤种群存活曲线属于典型的Deevey——Ⅲ型，种群早期死亡率高，后期存活值波动不大。桫椤种群生长过程中出现了三次死亡高峰期，死亡高峰期的出现可能是桫椤种群濒危的重要原因。 桫椤种存活率随龄级(高度级)增加呈单调减少，相应的积累死亡率呈单调增加，变动幅度为前期大，后期小，反映出种群在特定龄级上的生存及死亡状况；死亡密度函数曲线呈现前期下降，后期平缓稳定的特点，凹点出现于第4龄级；危险率函数曲线与死亡率曲线形式一致。 谱分析结果显示桫椤种群数量波动性是大周期内有小周期的多谐波的迭加，各周期作用大小不同，基本上随周期的减小而减小，基波的影响最显著，呈现出明显的大周期，同时存在着较明显的小周期波动，这种小周期波动可能与幼苗时期的环境筛作用有关。 (4) 通过桫椤个体地上部生态势消减系数、相对生活力参数，求得个体地上部生濒危植物橄锣种群生态学与生态场特性研究态场中不同距离以及不同生长状态下的生态势。8个不同地段的秒锣种群平均个体地上部生态场生态势最大值大小次序为Q5>邻>Q4>Q3>QS>Q7>Q2>Ql，个体小的秒锣个体地上部生态势小，个体大的生态势则大。 不同地段渺锣种群平均个体地上部生态势在场源植株茎干处最大，随着与场源植株距离的增大，生态势逐渐下降，最终以作用距离劣轴为渐近线在无穷远处收敛为零，各地段秒锣种群平均个体生态势的消减形式都近似于Ga鸣s汕分布. 以生态势为1 .00、1丫时的作用距离看作缈锣个体生态场有效作用的临界距离，则各地段渺锣种群平均个体地上部生态场有效作用距离从0.058、8.475m不等，作用面积在0.0036一38 1 .307扩，大小次序为QS>Q6>Q4>Q3>Q8>Q7>QZ>Ql. 秒锣个体地上部生态等势线是由茎蓦部向外呈发散状态，等势线的疏密程度反映场作用的程度。秒锣个体生态场空间模式近似一个三维空间的二元Ga理铭ian分布，个体势面的高低反映了场作用的强弱，势面的闭合范围则表征了场作用空间。 (5)反映生态势变化率的秒锣个体地上部生态场梯度随与场源距离的增加，先由小逐渐变大，在某一距离点上达到场梯度的最大值，随后又逐渐由大变小并收教于零，其变化形式符合Rayleigh分布. 不同地段的裕锣种群个体地上部场梯度大小变化幅度不同，最大场梯度值以及出现最大场梯度时的作用距离不同，且随作用距离增加，场梯度的收数速度差异较大，其受场源植株个体大小的影响。 (6)秒锣地上部种群中任意一点的生态场作用大小以生态等势线的疏密程度或生态势面的高低表征，结果显示，在个体数量差异不大的情况下，种群内生态场作用的强弱与种群内植株个体的大小具有明显的相关关系。地段Q3、Q4、Q5、Q6的秒锣种群以大、中型植株为主，个体生态场作用大，彼此间亚加强烈，形成的种群等势线较多，具有明显的梯度，呈现疏密不均变化;三?更多还原

【Abstract】 Study arid protection on endangered species is a major part of the contents of biodiversity which is one of hotspots of world’s studies. Alsophila spinulosa which is survival plant from the end of the Cretaceous Period and the forepart glacier of the Tertiary Period and one of the oldest living fossil in the world and the only remnant arboreal fern at present is Chinese endangered protective plant in the first class. The arboreal fern was been of great value for study on geologic climate and origin and evolution of plant and geographical flora besides it possesses horticultural ornamental and medicinal value and many other uses. So it is very significant for exploration of endangered mechanism, valid protection and exploitation and utilization of resource of Alsophila spinulosa as also protection of biodiversity etc to carry on ecological study on Alsophila spinulosa.Population ecology and ecological field characteristics of Alsophila spinulosa in different sites in Guaxi Alsophila spinulosa nature reserve in Fujian province were analyzed and discussed by quantitative statistic method in the work, including size structure, spatial distribution pattern and its fractal trait and life process of the population, as well as studies on character of ecological field and change law of field gradient of individual aboveground and ecological field property of population aboveground. The results indicated as follows:(1) By applying the method of "spatial sequence instead of temporal change". Size structures of Alsophila spinulosa populations in seven sites took on growing, stable, adult and senescent four kinds of forms with stem height as the indices of individual size.Spatial distribution patterns of Alsophila spinulosa populations in the different sites were different with the types of clump or random. Clump distribution appeared in the growing populations generally with stores of seedlings and a small quantity of adults and random distribution in the stable or senescent populations with more adults and less seedlings relatively. Possessing diffusivity, distribution pattern of Alsophila spinulosa population changed from clump to random in the course of development furthermore. Seedlings appeared as clump distribution, while large plants random. Degree of aggregation of the population patterns varied with the different sampling scales, values of dispersion index I decreasing with increment of quadrat scale by and large. Therefore, sampling scale had a certain effect on the measurement of spatial distribution pattern of Alsophila spinulosa population.(2) Alsophila spinulosa populations in 8 sites existed variant scale variation and fractal trait on spatial occupation, pattern intensity and spatial correlation of individuals. The box-counting dimension ranged from 0.3132 to 1.1189 and the order of that was Q3 > Q6 > Q7 > Ql > Q2 > Q4 > Q5 > Q8, information dimension from 0.3031 to 1.078 and the order of that Q3 > Q7 > Q6 > Ql > Q2 > Q5 > Q8 > Q4 and the correlation dimension from 0.7450 to 1.1453 and the order of mat Q3 > Q6 > Q8 > Ql > Q5 > Q7 > Q2 > Q4. The spectrum of fractal dimension showed that spatial structure characteristicses of those populations in sites Q1,Q2, Q3, Q6 and Q7 were similar, the same to those in sites Q4, Q5 and Q8.(3) Time-specific life table of Alsophila spinulosa population established based on highness class revealed that seedlings were abundant relatively and structure of the population was the type ascending in the primary stage and stable in the late stage. The survival curve belonged to the typical type of Deevey-III with the high mortality in the earliness and the survival values fluctuating not large in the late stage. In the process of development of the population, there were three death peaks of which occurrence was perhaps one of the important reason of population endangerment.Survivability of the population dropped down monotonously, and accumulative mortality rose up correspondently with increment of the age class (highness class) and varying extent was large in the earl更多还原