A DEMOGRAPHIC-STUDY OF 2 POPULATIONS OF THE SEAWEED ASCOPHYLLUM-NODOSUM
A DEMOGRAPHIC-STUDY OF 2 POPULATIONS OF THE SEAWEED ASCOPHYLLUM-NODOSUM
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DOI：
10.2307/1940691
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发表时间：
1992-08-01
期刊：
影响因子：
4.8
通讯作者：
ABERG, P
中科院分区：
文献类型：
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作者：
ABERG, P
很少有人知道的人口结构的大小结构的海藻种群，这是特别真实的种群在可变的环境。因此，用矩阵种群模型分析了棕色瘤叶藓的种群结构。这是建立在瑞典西海岸两个种群的3年研究基础上的，其中> 1100个个体每年被标记和跟踪两次。环境的变化是由于在一些冬季冰的存在。研究区域的冰年频率是已知的，并且在一个地点比另一个地点更高。在研究期间，两个地点都有2年有冰和1年没有冰，这些环境的时间变化导致了A.结节。个体被分为五个大小类和人口动态在没有冰的年份的特点是低死亡率和高的过渡概率增长到更大的尺寸，而多年的冰有高死亡率和高的过渡概率破碎到更小的尺寸。在生活史图中的25个可能的转变中，除了2个以外，所有的转变都有非零的条目，这意味着A.节瘤藻个体在所有五个大小级之间可以被描述为可塑性生长。对补充的粗略估计表明，这两个种群的数量在无冰年份都会增加，但在有冰的年份会减少。大小依赖的生育率可能会出现错误，因此生存矩阵与生育率函数建立在每个个体的总生殖生物量上，允许在不同水平的渐近生长率lambda（1）下分析人口统计学。种群之间的主要差异之一是，在无冰年的生存矩阵的稳定大小分布占主导地位的大小类4在一个人口，但类5在其他。因此，为了达到相同的λ（1）值，在以第4类为主的人口中需要更高的生育率。过渡矩阵的弹性分析显示了相同的趋势，尽管该分析的主要结果是，生长到更大的尺寸或保持在同一类别比繁殖对λ（1）的贡献更大。这对于所研究的所有lambda（1）水平都是有效的。
Very little is known about the demography in size-structured seaweed populations, and this is especially true for populations in variable environments. Thus, the demography of the brown alga Ascophyllum nodosum was analyzed with a matrix population model. This was built on a 3-yr study in two populations on the Swedish west coast, where > 1100 individuals were marked and followed twice each year. The environmental variability is due to the presence of ice during some of the winters. The frequency of ice years in the study area is known, and is higher at one site compared to the other. During the study there were 2 yr with ice and one without at both sites, and these temporal changes in the environment resulted in large variations in the vital rates of A. nodosum. The individuals were divided into five size classes and the population dynamics at years without ice were characterized by low mortality rates and high transition probabilities for growth to larger sizes, while years with ice had high mortality rates and high transition probabilities for breakage to smaller sizes. Of the 25 possible transitions in the life cycle graph all except 2 had nonzero entries, which means that the adult life of A. nodosum individuals can be described as plastic growth between all five size classes. A crude estimate of the recruitment showed that both populations will increase in numbers in ice-free years, but will decrease in years with ice. The size-dependent fertility rate is probably subject to errors, and thus the survival matrices were scaled with a fertility function built on total reproductive biomass per individual, allowing analyses of the demography at different levels of the asymptotic growth rate lambda(1). One of the main differences between the populations was that the stable size distribution for survival matrices in ice-free years was dominated by size class 4 at one population but class 5 at the other. Thus, to achieve the same value of lambda(1) higher fertility rates were needed at the population dominated by class 4. Elasticity analysis of the transition matrices showed the same trend, although the main result from that analysis was that growth to larger sizes or remaining in the same class contributed more to lambda(1) than reproduction. This was valid for all levels of lambda(1) investigated.