Pinus pinea stands have been identified as one of the target species for agroforestry systems in Europe. Its fruit yield is of importance to the local development, especially in the Mediterranean basin, due to its highly nutritional kernels and its economic value. The objectives of this study were to analyze the relation between pine nut and kernel weight and its efficiencies in relation to cone and tree traits for different stand structures. The statistical analysis was carried out with correlation, multiple correlation analysis, hurdle-gamma regression, principal component and cluster analysis, with a dataset of about 3300 cones collected in four plots and 3 years. The results indicate that pine nut and kernel and its efficiencies depend on stand structure, year and tree characteristics. The principal component analysis and the cluster analysis enabled the identification of four groups of trees related to the pine nut and kernel efficiencies. The higher efficiencies per tree are attained in stands managed for fruit production, increasing with the decrease of the density.

中文翻译：

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Pinus pinea (L.) 坚果和仁生产力与锥体、树木和林分特性的关系

松树已被确定为欧洲农林业系统的目标物种之一。由于其高营养的籽粒和经济价值，其果实产量对当地的发展具有重要意义，尤其是在地中海盆地。本研究的目的是分析松子与籽粒重量之间的关系，以及松子与不同林分结构的锥体和树木性状的效率之间的关系。统计分析采用相关性、多重相关性分析、障碍伽马回归、主成分和聚类分析，在四个地块和 3 年中收集了约 3300 个锥体的数据集。结果表明，松仁和松仁及其效率取决于林分结构、年份和树木特征。主成分分析和聚类分析能够识别出与松子和仁效率相关的四组树木。在为生产水果而管理的林分中，每棵树的效率更高，随着密度的降低而增加。