Callery pear (Pyrus calleryana Decne.), a native of eastern Asia, has recently emerged as an important woody invader in much of the eastern United States. Little is known about its ecology in its new range. Its shade tolerance may be an important indicator of areas it is likely to invade. In this study, allometric equations were first developed to predict aboveground biomass components, including wood, branches, bark, leaves, and fruit, from diameter at stump height (dsh; 25 cm), by destructively harvesting 13 trees, ranging from 0.1 to 19.3 cm dsh. Then, a total of 23 wild-grown stands in the northern Kentucky/southwestern Ohio region were surveyed, with diameters of all woody stems sampled. Pyrus calleryana density, basal area, aboveground biomass, stand density index, size distribution inequality, and importance value were calculated for each site. Two-factor Weibull distributions were fit to diameter distributions. Allometric equations provided good fits for total aboveground biomass as well as individual components. Aboveground biomass levels fell below mean levels of native forest stands found in the United States. Stand density indices yielded values typical of shade-intolerant or midtolerant species. Stands with smaller trees generally had steeply declining monotonic diameter distributions, while stands with larger trees trended toward positively skewed monotonic distributions. These findings are consistent with a species that is either shade-intolerant or midtolerant. Thus, while this species is expected to invade open or disturbed areas, it is not expected to be an important invader under forest canopies. However, its extended deciduous habit is one shared by other understory woody invaders, and so this may allow it to survive under forest canopies.

中文翻译：

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俄亥俄州西南部和肯塔基州北部的 Pyrus calleryana 异速生长方程和林分结构

Callery梨（梨Decne.) 原产于东亚，最近在美国东部大部分地区成为重要的木本入侵者。对其新范围内的生态知之甚少。它的耐荫性可能是它可能侵入的区域的一个重要指标。在这项研究中，首先开发了异速生长方程，通过破坏性收获 0.1 到 19.3 的 13 棵树，从树桩高度（dsh；25 厘米）的直径预测地上生物量成分，包括木材、树枝、树皮、叶子和果实厘米 dsh。然后，在肯塔基州北部/俄亥俄州西南部地区共调查了 23 个野生林分，并采样了所有木质茎的直径。梨计算了每个站点的密度、基底面积、地上生物量、林分密度指数、大小分布不平等和重要性值。两因子 Weibull 分布适合直径分布。异速生长方程很好地拟合了地上总生物量以及单个成分。地上生物量水平低于美国本土森林的平均水平。林分密度指数产生了典型的不耐阴或耐中树种的值。具有较小树木的林分通常具有急剧下降的单调直径分布，而具有较大树木的林分则倾向于正偏斜的单调分布。这些发现与不耐阴或耐中等的物种一致。因此，虽然该物种预计会入侵开阔或受干扰的地区，预计它不会成为森林树冠下的重要入侵者。然而，它延伸的落叶习性是其他林下木本入侵者所共有的习性，因此这可能使它能够在森林树冠下生存。