Comparative demography of plants based upon elasticities of vital rates
Comparative demography of plants based upon elasticities of vital rates
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DOI：
10.1890/02-0651
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发表时间：
2004-02-01
期刊：
影响因子：
4.8
通讯作者：
Silvertown, J
中科院分区：
文献类型：
--
作者：
Franco, M;Silvertown, J
来自人口投影矩阵的矩阵元素的弹性通常用于分析不同生命史转变（出生、存活、生长）对有限增长率（λ）的相对贡献。目前，基于矩阵模型的比较人口统计学依赖于将弹性矩阵分解为块，每个块包含被认为代表招募、停滞或向更大规模类别发展的矩阵元素。整个矩阵的弹性总和总是为1，不同的种群和物种可以根据这三个变量的相对比例进行比较。这种方法已被广泛使用，但它包含一个弱点，即矩阵元素的值是一个以上的生命率的函数。例如，表示进展到更大规模类别的转变涉及存活率以及生长率。因此，理想情况下，人口之间的人口统计比较应该使用生命率本身的弹性，而不是作为这些比率的复合物的矩阵元素的弹性。在这里，我们采用了一套完整的一般方程的弹性的生命率在一个全新的分析矩阵为102种多年生植物。结果表明，一个令人惊讶的相似性，以矩阵元素弹性的基础上，早期的分析，并提供重要的确认植物生活史和人口之间的相关性的一般模式。此外，我们还表明，个体生命率弹性本身无法预测生活史的变化。因此，所有三个人口统计过程（生存，生长和繁殖）是必要的，以解释生活史的变化。新的分析为比较人口学提供了更坚实的基础。
Elasticities of matrix elements from population projection matrices are commonly used to analyze the relative contributions of different life history transitions (birth, survival, growth) to the finite rate of increase (lambda). Hitherto, comparative demography based on matrix models has relied upon decomposing elasticity matrices into blocks, each containing matrix elements deemed to represent recruitment, stasis, or progression to larger size classes. Elasticities across an entire matrix always sum to unity, and different populations and species can be compared on the basis of the relative proportions of these three variables. This method has been widely used, but it contains a weakness in that the value of matrix elements is a function of more than one vital rate. For example, transitions representing progression to larger size classes involve a survival rate as well as a growth rate. Ideally, then, demographic comparisons between populations should be made using elasticities of vital rates themselves, rather than elasticities of matrix elements that are compounds of those rates. Here, we employ the complete set of general equations for the elasticity of vital rates in an entirely new analysis of matrices for 102 species of perennial plants. The results show a surprising similarity to an earlier analysis based upon matrix element elasticity and provide important confirmation of general patterns of correlation between plant life history and demography. In addition, we show that individual vital rate elasticities cannot, on their own, predict variation in life history. Therefore, all three demographic processes (survival, growth, and reproduction) are necessary to account for life history variation. The new analysis provides a firmer foundation for comparative demography.