Key message A positive effect of mixed pine forests ( Pinus sylvestris L. and Pinus pinaster Ait.) on the understory richness and tree regeneration was observed with respect to monospecific stands. Understory species typical of the native Pyrenean oak forests in the Iberian Peninsula contribute to maintaining high understory richness in such mixed pine forests. Context The influence of stands characteristics on the understory in mixtures that combine coniferous tree species of the same genus deserves more study since they are frequent in Spain. Aims To assess the effect of mixed versus monospecific stands of Pinus sylvestris L. and Pinus pinaster Ait. on the main tree species regeneration and understory species composition. Methods Tree regeneration and understory species composition were inventoried in eighteen forest plots (6 triplets) in North-Central Spain. Each triplet consisted of two plots dominated either by Scots pine or Maritime pine and one mixed plot that contained both species. Results The basal area (%) of both Pinus species was the only characteristic of the stands that significantly influenced the understory composition and tree regeneration. Characteristic species of humid and temperate zones, including P. sylvestris regeneration, dominated in Scots pine stands, and typical species of well-drained Mediterranean areas, including P. pinaster regeneration, dominated in Maritime pine stands. In mixed stands, the highest regeneration of the native Pyrenean oak with respect to monospecific stands was accompanied by understory species typical of native oak forests that share the same regeneration niche. Conclusion Mixed pine forests allow the development of understory species better than monospecific forests. Graphical abstract

中文翻译：

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混交松林能否通过改善原生橡树林典型林下物种的建立来保护林下丰富度？

关键信息 观察到混合松林（Pinus sylvestris L. 和 Pinus pinaster Ait.）对单种林分林下林木丰富度和树木再生的积极影响。伊比利亚半岛原生比利牛斯橡树林的典型林下物种有助于保持这种混合松林的林下丰富度。背景 林分特征对混合同一属针叶树种的林下林木的影响值得更多研究，因为它们在西班牙很常见。目的 评估樟子松和松子松的混合林分与单种林分的影响。主要树种更新和林下树种组成。方法 对西班牙中北部的 18 个森林地块（6 个三胞胎）中的树木更新和林下物种组成进行了清查。每个三元组由两个以苏格兰松或海松为主的地块和一个包含这两种物种的混合地块组成。结果 两种松树种的基面积 (%) 是林分的唯一特征，显着影响林下组成和树木更新。湿温带的特征树种，包括 P. sylvestris 更新，在苏格兰松林中占主导地位，而排水良好的地中海地区的典型物种，包括 P. pinaster 更新，在海松林中占优势。在混合看台上，就单种林分而言，本地比利牛斯橡树的最高再生伴随着具有相同再生生态位的典型本地橡树林的林下物种。结论 混交松林比单种林更能促进林下物种的发展。图形概要