Replication data for: The effect of reforestation on bird communities in two types of forests in the Nevado de Toluca, Mexico.

Numbers of individuals and volumes of the plant species from the three strata (herbaceous, shrub, trees), for the native forest (natural forest; Amanalco) and reforested forest (Cacalomacan), as well as the corrresponding Importance Value Index (IVI). The vegetation attributes were measured in February and March 2016 within a 20 x 12 m rectangle. Inside each rectangle, a mist net was the symmetry axis (dividing the rectangle in two). We counted all the trees from each species inside the rectangle and measured the diameters of all the trees at breast high (DBH) to the nearest 0.5 cm in small trees, and to the nearest 1.0 cm in large trees. We estimated the volume of each tree at DBH, and both the density of all the tree species. To estimate the attributes of shrub and herbaceous strata, we traced 20-meter-long perpendicular lines at the limits and at the midpoint of the net, being the net the midpoint of these lines. We estimated the volumes of the shrubs crossed by these lines. When it was possible to distinguish an individual shrub, we approximated its volume as the volume of a cylinder. When the shoots of different individuals were indistinguishable (“shrub wall”), we approximated their pooled volume as the volume of a cuboid and counted the number of shoots. The volume of the herbaceous stratus was estimated in a similar manner (Fig. 2). The determination of the volume of the species refers to occupation and was read from the regular cylinder formula (w × l × h), where: w – width, l – length and h – height. The total volume of each species was estimated as follows: 1. When it was possible to distinguish between individuals of the same species, the total volume was obtained by adding the volumes of the stems of each plant. 2. When it was not possible to distinguish between individuals of the same species, the total volume was measured as all the individuals as one. A different group of individuals was considered if there was a distance equal to or greater than 50 cm between two neighboring groups. For each rectangle, dominance was obtained by dividing the total volume of each species by the total volume of all the species. Density was obtained by dividing the number of individuals of each species among the total number of individuals of all the species in the stratum. The importance value index (IVI) was obtained by summing the dominance and the density. The same indices were calculated for shrubs and herbaceous.

本数据集涵盖原生林（天然林；Amanalco样地）与人工恢复林（Cacalomacan样地）三个植被层（草本层、灌木层、乔木层）的物种个体数与植株体积，同时包含对应的重要值指数（Importance Value Index, IVI）。植被属性调查于2016年2月至3月间开展，调查区域为12 m × 20 m的矩形样方。每个矩形样方内以雾网作为对称轴，将样方均分为两个区域。针对乔木层：对样方内所有乔木物种进行个体计数，并测定所有乔木的胸径（Diameter at Breast Height, DBH），其中小径木的胸径测定精度为0.5 cm，大径木为1.0 cm。基于胸径估算单株乔木体积，并计算所有乔木物种的种群密度。针对灌木层与草本层：以雾网的两端及中点为起始点，布设4条20 m长的垂直样线，雾网中点为所有样线的中点。统计样线穿过的灌木个体体积：若可区分单个灌木个体，则将其体积近似为圆柱体体积；若不同个体的枝条无法区分（即形成“灌丛墙”），则将其总体积近似为长方体体积，并统计枝条数量。草本层体积的估算方式与之类似（见图2）。物种体积的测定以植株空间占据量为依据，通过标准圆柱体体积公式（w×l×h，其中w为宽度、l为长度、h为高度）计算。各物种总体积的估算分为两种情况：1. 若可区分同一物种的不同个体，则将所有植株的茎干体积求和得到总体积；2. 若无法区分同一物种的个体，则将所有个体视为整体进行体积测量。若相邻两个植株群之间的距离≥50 cm，则视为两个独立的个体群。对于每个样方，物种优势度为该物种总体积占样方内所有物种总体积的比值；种群密度为该层内某物种的个体数占该层所有物种总个体数的比值。重要值指数（IVI）为优势度与密度之和。灌木层与草本层均采用相同方法计算上述指数。