ABSTRACT Background The Cerrado is a fire-prone Neotropical savanna and grass seeds are the main component of the soil seed bank. Although grass seeds are presumed to tolerate heat pulses during fires, the assumption that these seeds will be recruited may be an overestimation, since it does not account for factors that limit seedling emergence from the soil. Aims We tested if burial depth constrained the seedling emergence of nine common Neotropical savanna grasses. Methods Seeds were sown at the surface or at 5, 10, 20 and 30 mm in trays filled with cerrado soil. Emergence was assessed daily for 30 days and any remaining non-germinated seeds were tested for viability. Results Seedling emergence decreased with depth, and was positively related to the seed mass. Seven species showed a significant reduction in emergence when sown at 10 mm and only two species emerged from 30 mm. Most non-germinated seeds lost viability after 30 days. Conclusions Burial depth constrained the seedling emergence of Neotropical savanna grasses. Although seeds in the soil are protected during Cerrado fires, they may not generate new individuals, as seedling emergence is limited once a depth of 10 mm is reached and the seeds lose viability within 30 days in humid soil.

中文翻译：

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防火，但不受伤害：稀树草原草的幼苗出苗受到埋藏深度的限制

摘要背景塞拉多是一个容易发生火灾的新热带稀树草原，草种子是土壤种子库的主要成分。虽然假定草种子在火灾期间耐受热脉冲，但这些种子将被招募的假设可能被高估了，因为它没有考虑限制幼苗从土壤中出苗的因素。目的 我们测试了埋藏深度是否限制了九种常见的新热带稀树草原草的幼苗出现。方法 将种子播种在地表或 5、10、20 和 30 毫米处，种植在填充有塞拉多土壤的托盘中。每天评估出苗情况，持续 30 天，并测试任何剩余的未发芽种子的活力。结果出苗量随深度增加而减少，与种子质量呈正相关。当播种到 10 毫米时，七个物种的出苗率显着降低，而在 30 毫米播种时，只有两个物种出苗。大多数未发芽的种子在 30 天后失去活力。结论埋藏深度限制了新热带稀树草原草的出苗。尽管土壤中的种子在 Cerrado 火灾期间受到保护，但它们可能不会产生新个体，因为一旦达到 10 毫米的深度，幼苗的出现就会受到限制，并且种子在潮湿的土壤中会在 30 天内失去活力。