Context Neighbouring forests constitute biological sources that enable the succession from species-poor systems, such as tree-plantings, to highly diverse forests. However, old forest patches are becoming rare in tropical agricultural landscapes. Objective We were interested in if, and how, spontaneous regeneration under tree-plantings reflects the age and the amount of the neighbouring forest cover. We anticipated that older forests promote a compositionally broader recovery in neighbouring tree-plantings, because older forests likely include disturbance-sensitive species, particularly within least deforested landscapes. Methods We studied twenty-seven restoration sites implemented as tree-plantings in the Brazilian Atlantic Forest. We quantified the effects of age and amount of neighbouring forest cover on structural and compositional characteristics of the regeneration community (dbh < 5 cm). We used two landscape groups (presence, or absence, of forests older than 30 years.) with a similar areal range of forest cover, enabling the disentanglement of forest age from forest amount effects on regeneration community responses. Results Surprisingly, we found that greater forest cover correlated with denser and more species-rich regeneration communities only when neighbouring forests were young. This pattern was promoted by non-vertebrate dispersed species. Regeneration communities in tree-plantings near to young forests had lower seed-mass and relative abundances of forest-specialists, compared to communities found near old forest patches. Conclusion Regeneration is likely denser in landscapes of vast young-forest coverage. However, small-seeded and habitat-generalist species, frequently related to disturbance tolerance, tend to be dominant if old-growth forests are far away. This biased seed source appears to preclude the restoration of typical historic tropical forest composition.

中文翻译：

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恢复热带森林组成更困难，但当邻近的森林还年轻时，恢复树木覆盖的速度更快

背景 邻近的森林构成了生物源，使物种贫乏的系统（例如植树）能够演替到高度多样化的森林。然而，古老的森林斑块在热带农业景观中变得越来越少。目标 我们感兴趣的是植树下的自发更新是否以及如何反映邻近森林覆盖的年龄和数量。我们预计，较旧的森林会促进邻近植树的成分更广泛的恢复，因为较旧的森林可能包括对干扰敏感的物种，特别是在森林砍伐最少的景观中。方法 我们研究了巴西大西洋森林中作为植树计划实施的 27 个恢复地点。我们量化了年龄和邻近森林覆盖量对再生群落结构和组成特征的影响（dbh < 5 cm）。我们使用了具有相似森林覆盖面积范围的两个景观组（存在或不存在超过 30 年的森林），从而能够将森林年龄与森林数量对更新群落响应的影响分开。结果 令人惊讶的是，我们发现只有当邻近的森林年轻时，更大的森林覆盖率与更密集、更丰富物种的再生群落相关。这种模式是由非脊椎动物分散的物种促进的。与在老森林斑块附近发现的社区相比，靠近年轻森林植树的再生社区的种子质量和森林专家的相对丰度较低。结论 在广阔的年轻森林覆盖的景观中，再生可能更密集。然而，如果原始森林距离很远，则通常与干扰耐受性相关的小种子和栖息地通用物种往往占主导地位。这种有偏见的种子来源似乎排除了典型的历史热带森林组成的恢复。