Abstract Herbs may affect the recruitment of woody species. However, most studies have evaluated the impact of one particular herb species or the herbaceous layer as a whole. It is less known if different herb species have different effects on recruitment of woody species, and whether these effects depend on environmental conditions. In this paper, we evaluated the effects of different native and exotic herb species on recruitment of nine woody species in central Chile, under different conditions of shading and precipitation. The experiment was carried out in an open ruderal area in Santiago, Chile. We conducted a factorial experiment with 360 1 × 1 m pots with monospecific crops of eight herb species and a control without herbs, two levels of irrigation (245 and 534 mm) simulating two precipitation regimes, and the presence or absence of artificial shade simulating a woody canopy. Nine woody species common to the region were sown in each pot. Luminosity (PAR), soil moisture, herb volume, richness of woody species and seedling density of woody species recruited were measured. The effects of herb species on woody species richness varied from neutral in the open condition to mainly negative in the shaded condition. Differences in irrigation did not modify the effects of herbs on species richness. The effects of herb species were more variable when woody species were considered individually. Negative and neutral effects predominated, although some positive effects were observed under shaded and wetter conditions. Our results suggest that different herb species have distinct effects on recruitment of specific woody species and species richness, which mainly depend on shade conditions and secondarily on the precipitation regime, and that herb-woody species interactions are highly specific. Thus, management focused in herb controlling should be species-specific, in terms of herb and woody species, and dependent on climate and woody cover.

中文翻译：

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不同遮荫和降水条件下草本层对木本植物补充的物种特异性影响

摘要 草本植物可能会影响木本物种的补充。然而，大多数研究评估了一种特定草本物种或整个草本层的影响。鲜为人知的是，不同的草本植物对木本植物的补充是否有不同的影响，以及这些影响是否取决于环境条件。在本文中，我们评估了在不同遮荫和降水条件下，不同本地和外来草本植物对智利中部 9 种木本植物补充的影响。实验是在智利圣地亚哥的一个开阔的荒野地区进行的。我们对 360 个 1 × 1 m 的盆栽进行了一项因子试验，盆栽有 8 种草本植物的单一品种作物和不含草本植物的对照，模拟两种降水情况的两种灌溉水平（245 和 534 毫米）以及模拟木质树冠的人造树荫的存在与否。每个盆栽种了该地区常见的九种木本植物。测量了光度 (PAR)、土壤水分、药草体积、木本物种的丰富度和招募的木本物种的幼苗密度。草本植物对木本物种丰富度的影响从开放条件下的中性到阴影条件下的主要负面影响不等。灌溉的差异并未改变草药对物种丰富度的影响。当单独考虑木本物种时，草本物种的影响更加可变。尽管在阴暗和潮湿的条件下观察到了一些积极的影响，但负面和中性影响占主导地位。我们的结果表明，不同的草本物种对特定木本物种的补充和物种丰富度有不同的影响，这主要取决于遮荫条件，其次取决于降水状况，并且草本木本物种的相互作用是高度特异性的。因此，以草本植物控制为重点的管理应针对草本植物和木本物种，并取决于气候和木本覆盖物。