Cecropia (Urticaceae) trees continuously shed their old large leaves, which fall directly on the forest floor (ground stratum) or accumulate on the aboveground vegetation under Cecropia canopies (vegetation stratum). Since twig-nesting ants are expected to be more nest site limited in the higher forest strata than at ground level, we predict that richness, abundance, and colonization frequency of ant nests in Cecropia petioles are greater in the vegetation stratum when compared with ground stratum. During June 2019, fifteen trees of C. obtusifolia were sampled in a tropical rainforest, in Veracruz, Mexico. For each tree, we collected ten dry fallen petioles per stratum, for 300 petioles in total. We recorded 44 ant nests from 21 ant species. Forty-two nests were found in individual petioles, although in one case a single petiole housed two different ant species. Thirty-four (23%) petioles were colonized in the vegetation stratum and only nine (6%) in the ground stratum. At tree scale, ant nest richness and abundance were significantly greater in the vegetation stratum. Furthermore, frequency of petiole colonization per tree was greater in the vegetation stratum (14 trees; 93.3%) when compared with the ground stratum (5 trees; 33.3%). A stratified pattern of ant occupation in natural nesting sites was observed, supporting that twig-nesting ants are more nest site limited in the upper forest strata than at ground level. Because nesting sites are a limiting resource for arboreal twig-nesting ants, we suggest that Cecropia trees are key components of tropical forests that maintain arboreal ant diversity by promoting nesting sites through dry fallen petioles.

中文翻译：

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蚂蚁在 Cecropia obtusifolia Bertol 的干落叶柄中筑巢。（荨麻科）：垂直分层和巢址限制

天竺葵（荨麻科）树不断脱落老旧的大叶子，直接落在森林地面（地层）或堆积在天竺葵树冠下的地上植被（植被层）上。由于预计树枝筑巢蚂蚁在较高的森林地层中的巢址限制比地面更多，因此我们预测，与地面层相比，在植被层中，天蚕叶柄中蚂蚁巢穴的丰富度、丰度和定殖频率更高. 2019 年 6 月，在墨西哥韦拉克鲁斯的热带雨林中对 15 棵钝叶 C. obtusifolia 树进行了采样。对于每棵树，我们每层收集 10 个干燥的落叶叶柄，总共 300 个叶柄。我们记录了来自 21 种蚂蚁的 44 个蚁巢。在单个叶柄中发现了 42 个巢穴，尽管在一个案例中，一个叶柄容纳了两种不同的蚂蚁物种。三十四个 (23%) 叶柄在植被层中定居，只有九个 (6%) 在地层中。在树尺度上，植被层中的蚁巢丰富度和丰度显着更高。此外，与地面层（5 棵树；33.3%）相比，植被层（14 棵树；93.3%）中每棵树的叶柄定植频率更高。观察到蚂蚁在自然筑巢地点的分层模式，支持树枝筑巢蚂蚁在上层森林地层中的筑巢地点比在地面上更受限制。因为筑巢地点是树栖树枝筑巢蚂蚁的有限资源，