Effects of age and size on life histories and population growth of Rhododendron maximum shoots
Effects of age and size on life histories and population growth of Rhododendron maximum shoots
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年龄和大小对杜鹃最大芽生活史和种群生长的影响
DOI：
10.1002/j.1537-2197.1989.tb11291.x
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发表时间：
1989
影响因子：
3
通讯作者：
J. McGraw
中科院分区：
文献类型：
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作者：
J. McGraw
利用1984年6月和1985年6月的种群普查，对常绿林下灌木大杜鹃幼枝生活史进行了研究。大多数枝条(65%)在没有分枝或开花的情况下存活，较少的枝条(2%)、开花(20%)或死亡(23%)在两次普查之间。存活、分枝、开花或死亡的概率都与年龄和大小有关。叶面积增加，幼嫩枝小。开花主要集中在叶面积超过200 cm~2的3~6年生枝条上，开花率随叶面积的增大而增加。分枝通常发生在开花后的第二年。种群的年龄和大小分布在年际间发生了显著的变化，表明种群是非平衡的。成活时间表为Deevey Type I，表明幼芽得到了高度的“父母照顾”。基于年龄和年龄+大小的人口统计模型预测了十年内嫩枝数量的快速下降，而基于大小的模型预测了嫩枝数量的下降要慢得多。对模型的敏感性分析表明，枝条和增加叶面积的枝条对总体枝条种群增长有正向影响，而对失去叶面积、死亡或开花的枝条有负影响。讨论了地上部生活史在决定个体植物适合度和生态优势度方面的作用。植物由两个层次的种群组成：“传统的”个体种群，每个个体由一粒种子发育而来；以及个体内部发现的部分种群，如新梢、树叶或花蕾(White，1979；Harper，1980)。植物部分的人口统计学已成为确定植物生长速度的重要工具，特别是在需要非破坏性生长分析方法的田间条件下(Garbut和Bazzaz，1983；McGraw和Antonovics，1983；Chester和McGraw，1983；Fetcher和Shaver，1983；Cooper和McGraw，1988)。此外，应用于植物部分种群的人口统计模型可以潜在地预测植物的未来生长。传统上，人口学家根据年龄对个体进行分类，因为随着时间的推移，生存和生殖方面的重大变化会发生。然而，在植物种群中，发育速度是高度可塑性的。因此，大小与存活和繁殖力相关，而年龄对植物表现的预测相对较差。这导致收到了1986年9月17日出版的预览稿；1988年5月24日接受了修订本。作者要感谢哈尔·卡斯韦尔和大卫·彼得森对这份手稿进行了批判性的评论，并感谢哈尔·卡斯韦尔进行了对数线性分析。基于大小的全植物种群模型(Lefkovitch，1965)的错误(Werner和Caswell，1977；Caswell和Werner，1978；在Caswell，1986中评论)。还没有建立用于人口统计分析的植物部分分类的适当基础。先验的、基于年龄的模型似乎更合适，因为植物部分的大小往往比整个基因组的大小变化小得多(White，1979,1984)。然而，植物各部分中确实存在的枝条大小的变异性可能反映了内部资源可获得性或资源捕获能力的重要差异，因此作为分类变量比年龄更相关。基于年龄和大小的人口统计模型都被用于植物部分(Bazzaz和Harper，1977；Fetcher和Shaver，1983；McGraw和Antonovics，1983；Chester和McGraw，1983；Huenneke和Marks，1987)，尽管这两种方法没有在同一种群上进行直接比较。还开发了第三个人口统计模型，允许按年龄和大小进行分类(Law，1983)，尽管它尚未应用于植物部分的种群。在本研究中，我同时将基于年龄、大小和年龄+大小的模型应用于相同的枝条种群。除了将其用作生长分析的工具外，了解植物部分的人口统计学还可以解释个体的差异。
Ageand size-specific shoot life histories were studied with population censuses in June 1984 and June 1985 in an evergreen understory shrub, Rhododendron maximum. Most shoots (65%) survived without branching or flowering, and lesser numbers branched (2%), flowered (20%), or died (23%) during the year between censuses. The probabilities of surviving, branching, flowering or dying were both ageand size-dependent. Small, young shoots increased in leaf area. Flowering occurred most prominently in 3to 6-year old shoots that had exceeded a leaf area of 200 cm2, and the rate of flowering increased proportionately with size above this threshold. Branching normally occurred in the year following flowering. The age and size distributions of the population shifted significantly between years, indicating a nonequilibrium population. The survival schedule was Deevey Type I, indicating a high degree of "parental care" of young shoots. Ageand age + size-based demographic models predicted a rapid decline of the shoot population over a decade, while a size-based model predicted a much slower decline in shoot numbers. A sensitivity analysis of the models showed that overall shoot population growth was positively influenced by branching shoots and shoots that added leaf area, and negatively influenced by shoots that lost leaf area, died, or flowered. The role of shoot life histories in determining individual plant fitness and ecological dominance is discussed. PLANTS COMPRISE POPULATIONS at two levels; the "traditional" population of individuals, each of which developed from a single seed, and the population of parts such as shoots, leaves or buds that is found within each individual (White, 1979; Harper, 1980). The demography of plant parts has become an important tool for determining growth rates of plants, especially under field conditions where a nondestructive method of growth analysis is desirable (Garbutt and Bazzaz, 1983; McGraw and Antonovics, 1983; Chester and McGraw, 1983; Fetcher and Shaver, 1983; Cooper and McGraw, 1988). In addition, demographic models applied to populations of plant parts can potentially predict future growth of the plant. Demographers traditionally classify individuals by age because significant changes in survival and reproduction occur with development through time. However, developmental rate is highly plastic in plant populations. Size is therefore correlated with survival and fecundity, while age is a relatively poor predictor of plant performance. This has led to a prefI Received for publication 17 September 1986; revision accepted 24 May 1988. The author would like to thank Hal Caswell and David Peterson for critical reviews of this manuscript, and Hal Caswell for performing the log-linear analysis. erence for size-based models (Lefkovitch, 1965) of populations of whole plants (Werner and Caswell, 1977; Caswell and Werner, 1978; reviewed in Caswell, 1986). The appropriate basis for classification of plant parts for demographic analyses has not been established. A priori, age-based models may seem more appropriate since plant parts tend to be much less variable in size than whole genets (White, 1979, 1984). However, variability in shoot size that does exist within plant parts may reflect important differences in internal resource availability or resource capturing ability, and thus be more relevant than age as a classification variable. Both ageand size-based demographic models have been employed for plant parts (Bazzaz and Harper, 1977; Fetcher and Shaver, 1983; McGraw and Antonovics, 1983; Chester and McGraw, 1983; Huenneke and Marks, 1987), although direct comparisons of the two approaches have not been made on the same population. A third demographic model has also been developed that allows classification by both age and size (Law, 1983), although it has not been applied to populations of plant parts. In the present study, I simultaneously applied age-, size-, and age + size-based models to the same shoot population. In addition to its use as a tool in growth analysis, understanding the demography of plant parts can explain variation in individual
影响因子：
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作者：
C. Monk;D. T. McGinty;Frank P. Day join
通讯作者：
C. Monk;D. T. McGinty;Frank P. Day join