Disentangling long- and short-term changes in perennial organ functions in seasonal environments: a model of foliar chlorophyll and nitrogen in saplings of four evergreen broad-leaved trees
Disentangling long- and short-term changes in perennial organ functions in seasonal environments: a model of foliar chlorophyll and nitrogen in saplings of four evergreen broad-leaved trees
复制标题
解开季节性环境中多年生器官功能的长期和短期变化：四种常绿阔叶树幼苗叶绿素和氮的模型
DOI：
10.1007/s11099-015-0145-y
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发表时间：
2015
期刊：
影响因子：
2.7
通讯作者：
T.
中科院分区：
文献类型：
--
作者：
Mizusaki;D.;Umeki;K.;Honjo;T.
季节性环境中树木多年生器官功能的时间变化可分为长期的年际变化和单年内的季节波动。然而，很少有研究单独量化这些变化的纵向测量数据或分析它们之间的关系。我们开发了一个分层贝叶斯统计模型，由三个部分组成：一个长期的年际变化表示连续的年度线性趋势，季节性波动与26个值的两个星期期间在一年内，和重复测量的随机效应。该模型可以从纵向重复测量数据中提取长期的年际变化和季节波动。通过模型参数的估计，给出了季节波动的模式、季节波动的量和年净变化。我们应用我们的模型，叶片叶绿素（Chl）和氮（N）含量重复测量超过1岁的幼树在四个万年青阔叶树种的叶片，使用非破坏性光学方法。该模型成功地解释了叶绿素和氮含量的变化。在一般情况下，季节性波动对应当年叶的物候;叶绿素和N往往减少从开放到成熟的新叶和增加在休息期间。当年叶生长期叶绿素和氮含量的下降幅度（Δγ）并不随叶龄的增加而明显减小。不同品种叶绿素含量的变化趋势是，Δγ与叶片开放前的最大值呈显著正相关。对于氮含量，Δγ与开叶前的最大值在物种间相关性不明显，但在某些物种内呈显著正相关。叶绿素和氮的年度线性趋势的模型参数从正值（表示增加的趋势）到负值（表示减少），这取决于物种和叶龄。
Perennial organ functions of trees living in seasonal environments exhibit temporal changes that can be classified as long-term interannual changes and seasonal fluctuations within single years. However, few studies have separately quantified these changes from longitudinal measurement data or analyzed the relationships between them. We developed a hierarchical Bayesian statistical model consisting of three parts: a long-term interannual change expressed by consecutive annual linear trends, seasonal fluctuations with 26 values for two-week periods in a year, and a random effect for repeated measurements. The model can extract long-term interannual changes and seasonal fluctuations from longitudinal repeated measure data. The pattern of seasonal fluctuation, the amount of seasonal fluctuation, and the net annual change are expressed by the estimated model parameters. We applied our model to foliar chlorophyll (Chl) and nitrogen (N) content measured repeatedly on more than 1-year-old leaves of saplings in four evergreen broad-leaved tree species using nondestructive optical methods. The model successfully explained large variations in the Chl and N content. In general, seasonal fluctuations corresponded to the phenology of current-year leaves; Chl and N tended to decrease from the opening to maturation of new leaves and increased during the rest period. The magnitude of the decrease in the Chl and N content in the growth period of current-year leaves (Δγ) did not decrease noticeably as leaves aged. For the Chl content, Δγ was positively correlated with the maximum value before leaf opening across species. For the N content, Δγ and the maximum value before leaf opening were not clearly correlated across species, but were positively correlated within some species. A model parameter for annual linear trends in Chl and N varied from positive (indicating increasing trends) to negative values (indicating decrease) depending on species and leaf age in years.