Long-term dynamics of loblolly pine crown structure and aboveground net primary production as affected by site quality, planting density and cultural intensity
Long-term dynamics of loblolly pine crown structure and aboveground net primary production as affected by site quality, planting density and cultural intensity
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DOI：
10.1016/j.foreco.2020.118259
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发表时间：
2020-09
影响因子：
3.7
通讯作者：
Dehai Zhao;B. Bullock;C. Montes;Mingliang Wang;J. Westfall;J. Coulston
中科院分区：
文献类型：
--
作者：
Dehai Zhao;B. Bullock;C. Montes;Mingliang Wang;J. Westfall;J. Coulston
树冠属性对造林操作的响应和林分结构的许多方面的调节都很容易，因此它们动态地影响林分生产。许多研究报道了树冠结构对集约栽培或林分密度的反应，以及林分发展早期阶段叶量与生长效率之间的关系。长期的树冠结构及其与生长的关系的时间模式的研究要少得多。利用两个火炬松密度栽培研究的长期复测数据，采用协方差分析和线性混合效应模型，研究了造林密度、栽培强度和立地质量对火炬松树冠结构、林分地上净初级生产力（ANPP）和生长效率的影响。利用480株破坏性取样树木的数据，Dirichlet回归建模方法被用来分析树叶和树冠生物量分配之间的下，中，上三分之一冠部分。不同栽培强度林分叶生物量的时间变化规律不同。增加造林密度或提高立地质量均能促进火炬松木材生产。净初级生产力一般随立地质量的提高而增加，这主要是由于林分发育早期林分叶片生物量的增加，而林分发育后期林分生长效率的提高。更密集的文化处理增加了叶生物量，从而增加了ANPP在早期年龄，此后文化强度并不影响叶生物量，ANPP，和生长效率。早期年龄增加的趋势，增加种植密度导致的叶生物量和ANPP不成立与林分的发展。校正树的大小和优势的影响后，文化强度仍然改变了叶生物量的垂直分布。更密集的文化导致向上移动的树叶生物量。
Crown attributes respond readily to silvicultural manipulations and mediate many aspects of stand structure, consequently they dynamically influence stand production. Numerous studies reported crown structure responses to intensive cultures or stand density and the relation between foliage quantity and growth efficiency at early stages of stand development. Long-term temporal patterns of crown structure and its relation to growth have been much less studied. With long-term remeasurement data from two loblolly pine culture-by-density studies, the roles of planting density, cultural intensity and site quality on crown structure, stand aboveground net primary production (ANPP), and growth efficiency were investigated using ANCOVA and linear mixed-effects modeling approaches. Using data from 480 destructively sampled trees, the Dirichlet regression modeling approach was used to analyze foliage and crown biomass allocations among the lower-, middle- and upper-third crown sections. Stands under different cultural intensities showed different temporal patterns of foliage biomass. Increased planting density or higher site quality enhanced wood production of loblolly pine. ANPP generally increased with increasing site quality, due to increased stand foliage biomass in the early stage of stand development, and mainly due to increased growth efficiency in the late stages of stand development. More intensive cultural treatments increased foliage biomass, thus increased ANPP at early ages; thereafter cultural intensity did not affect foliage biomass, ANPP, and growth efficiency. The trend of early age increases in both foliage biomass and ANPP resulting from increased planting density did not hold true with stand development. After correcting for the effects of tree size and dominance, cultural intensity still altered the vertical distribution of foliage biomass. More intensive culture resulted in an upward shift of foliage biomass.