AGE STRUCTURE MODELS OF BALSAM FIR AND EASTERN HEMLOCK
AGE STRUCTURE MODELS OF BALSAM FIR AND EASTERN HEMLOCK
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DOI：
10.2307/2258822
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发表时间：
1976-01-01
影响因子：
5.5
通讯作者：
LOUCKS, OL
中科院分区：
文献类型：
--
作者：
HETT, JM;LOUCKS, OL
探索了植物种群在整个生命周期中动态的定量方法，包括估计重要种群统计数据和检查这些参数随时间的变化。目的是检查描述香脂树和加拿大香树种群减少的数学模型，并使用这些模型来解释这些树种的死亡率和生物学的其他方面。研究的模型是负指数、幂函数和负指数正弦波。负指数意味着恒定的死亡率，并且已在之前的研究中用于描述幼苗和草药的年龄结构。幂函数是一系列分布中的一个，可以适应生存模式遵循正偏态分布的人群，这意味着死亡率的变化。负指数模型不能充分描述长寿物种的年龄损耗；如果忽略与直线拟合的波状偏离，则幂函数是一个足够的模型。所有香脂冷杉和铁杉种群都显示出围绕前两个分布的直线形式的振荡。开发了正弦波模型来确定是否可以更充分地描述种群分布以及每个物种是否出现特征波长。正弦波模型似乎是最好的。建议根据林分结构变化导致的存活率逐渐变化来解释该周期。
A quantitative approach to the dynamics of plant populations throughout a long life-span is explored, including estimation of vital population statistics and examination of these parameters through time. The objective was to examine mathematical models describing population depletions in A. balsamea and T. canadensis and to use the models to interpret mortality rates and other aspects of the biology of these tree species. The models investigated were the negative exponential, the power function and a negative exponential sine wave. The negative exponential implies a constant mortality rate, and has been used in previous studies to describe age-structure of seedlings and herbs. The power function is one of a family of distributions that could be fitted to populations with a survival pattern following a positively skewed distribution, implying a changing mortality rate. The negative exponential model does not adequately describe age depletions in long-lived species; the power function is an adequate model if wave-like departures from the straight line fits are overlooked. All of the balsam fir and hemlock populations showed an oscillation around the straight line form of the first 2 distributions. A sine wave model was developed to determine whether the population distributions could be described more adequately and whether a characteristic wave length occurred for each species. The sine wave model appears to be the best. An explanation of the cycle in terms of gradual changes in survivorship due to changes in stand structure is suggested.