Growth rate reduction causes a decline in the annual incremental trunk growth in masting Fagus crenata trees
Growth rate reduction causes a decline in the annual incremental trunk growth in masting Fagus crenata trees
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DOI：
10.1093/treephys/tpx081
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发表时间：
2017-10-01
期刊：
影响因子：
4
通讯作者：
Han, Qingmin
中科院分区：
文献类型：
--
作者：
Kabeya, Daisuke;Inagaki, Yoshiyuki;Han, Qingmin
树干年生长量在大年明显减少。有两个假设可以解释这种现象的机制：(1)由于将资源分配从体细胞生长转移到种子生产，导致生长持续时间的缩短；(2)由于体细胞生长和生殖之间同时共享资源，导致生长速度下降。在这项研究中，我们旨在从资源配置的角度来检验这些假说。用数字树枝测量仪监测了无繁殖年份(2014)和丰产年份(2015)中的径向生长模式。同时，通过从冠层顶部取样枝条来监测枝条的生长规律。用数字树形计得到的数据用S型函数进行拟合，并用分层贝叶斯方法估计函数的参数；估计的参数用来表示树干生长物候的特性。2014年和2015年，大果树(F-15)和限果树(NF15)的树干生长在叶片展开后同步开始。2015年，再生产降低了增长率。这是由于资源被分配给壳斗的发育和相对粗大的枝条的形成，这两者都与树干生长同时发生。尽管种子成熟是在树干停止生长后开始的，但F-15和NF15在这两年中径向生长的持续时间没有明显差异。因此，2015年F-15的树干年半径增量有所减少。这些结果表明，径向生长速率的降低(假设2)导致了该物种繁殖树的树干年生长量的减少。
Tree trunk annual increments are markedly reduced in mast years. There are two hypotheses that could explain the mechanism for this phenomenon: (1) a reduction in the duration of growth due to switching the resource allocation from somatic growth to seed production; (2) reduction of growth rate due to resources being shared between somatic growth and reproduction simultaneously. In this study, we aimed to test these hypotheses in Fagus crenata Blume from the point of view of resource allocation. The radial growth patterns in F. crenata during a year without reproduction (2014) and a masting year (2015) were monitored using a digital dendrometer. At the same time, shoot growth patterns were monitored by sampling branches from the top of the canopy. Data obtained using the digital dendrometer were fitted to a sigmoidal function, and the parameters of the function were evaluated with a hierarchal Bayesian approach; estimated parameters were used to represent the properties of trunk growth phenology. Trunk growth started synchronously just after leaf unfurling in both mass-fruiting (F-15) and limited-fruiting (NF15) trees in 2014 and 2015. Reproduction reduced the growth rate in 2015. This was due to the resources being allocated for the development of cupules and for formation of relatively thick branches, both of which occurred simultaneously with trunk growth. There was no clear difference in the duration of radial growth between F-15 and NF15 trees in the 2 years, although seed maturation started after trunk growth ceased. As a result, the annual trunk radius increment was reduced in the F-15 trees in 2015. These results suggested that reduction of radial growth rate (Hypothesis 2) caused the reduction in annual trunk increment of reproducing trees of this species.