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首页> 外文期刊>Forest Ecology and Management >Effects of planting density on canopy dynamics and stem growth for intensively managed loblolly pine stands.
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Effects of planting density on canopy dynamics and stem growth for intensively managed loblolly pine stands.

机译：集约种植对强化管理火炬松林分冠层动态和茎生长的影响。

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Leaf area index (LAI), intercepted photosynthetically active radiation (IPAR), and foliar nitrogen content are related to stand growth. However, they are all a function of canopy size, and their relative importance is hard to determine. We used intensively managed 4-year old loblolly pine (Pinus taeda) stands (located in Piedmont and Upper Coastal Plain of Georgia, USA) planted at densities ranging from 740 to 4440 trees ha-1 that possessed very different canopy structures to separate the relationships between IPAR, LAI, and foliar N content. Our objectives were to determine whether stem growth was best correlated with LAI, IPAR, or foliar N content, and to determine how the relationship between LAI and IPAR varied among stands of different planting densities. While stem growth rates increased significantly with planting density, from 12.0 to 35.2 m3 ha-1 y-1, increases were not proportional, indicating the presence of competition-induced limitations to growth. Annual IPAR (863-2345 MJ m-2 y-1), LAI (2.5-4.9), and foliar N content (67-122 kg ha-1) all increased as stand density increased from 740 to 4440 trees ha-1. Stem growth rates were better correlated with annual IPAR (r2=0.90), than LAI (r2=0.67) or foliar N content (r2=0.55). The efficiency of LAI to capture radiation (IPAR LAI-1) increased with stand density even though the higher density stands possessed greater LAI, which increased the likelihood of within canopy shading. The increase in IPAR LAI-1 corresponded to significantly decreased variation in light interception within plots as planting density increased. These results indicate that stem growth is best correlated with annual IPAR and underscore the importance of stand structure since the more even distribution of foliage within canopies of higher density stands increased the efficiency of light interception.
机译：叶面积指数（LAI），截获的光合有效辐射（IPAR）和叶面氮含量与林分生长有关。但是，它们都是树冠大小的函数，它们的相对重要性很难确定。我们使用了经过严格管理的4年生火炬松（Pinus taeda）林分（位于美国乔治亚州皮埃蒙特和上沿海平原），种植密度为740至4440棵ha-1树，这些树ha-1具有非常不同的冠层结构以分离关系IPAR，LAI和叶面N含量之间的关系。我们的目标是确定茎生长是否与LAI，IPA或叶面N含量最佳相关，并确定LAI和IPAR之间的关系在不同种植密度的林分之间如何变化。尽管茎的生长速度随种植密度的增加而显着增加，从12.0增至35.2 m3 ha-1 y-1，但增长却不成比例，表明存在竞争引起的生长限制。随着林分密度从740棵ha-1增加到4440棵ha-1，年度IPAR（863-2345 MJ m-2 y-1），LAI（2.5-4.9）和叶面氮含量（67-122 kg ha-1）均增加。茎生长率与年度IPAR（r2 = 0.90），LAI（r2 = 0.67）或叶面氮含量（r2 = 0.55）的相关性更好。 LAI捕获辐射的效率（IPAR LAI-1）随着林分密度的增加而增加，即使更高密度的林分拥有更大的LAI，这也增加了树冠内阴影的可能性。随着种植密度的增加，IPAR LAI-1的增加对应于小区内光截获的变化显着减少。这些结果表明，茎的生长与年度IPAR最佳相关，并强调了林分结构的重要性，因为在密度较高的林分内，更均匀的枝叶分布增加了光截获的效率。

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