Grasses are recognized as a critical regeneration barrier in tropical pastures, yet the effects of rodents and rodent–grass interactions are not well understood. As selective foragers, rodents could shape tree communities, moderating biodiversity in regenerating tropical landscapes. We utilized a fully crossed two-way factorial design to examine the effect that grasses, rodents, and their interaction had on tree seedling establishment in pasture habitat. We followed two separate tree cohorts for 1 year each within the experimental framework. Multiple cohorts were used to better represent successional tree species variation and responses. Trees species were characterized by a gradient of seed masses and as pioneer or persistent successional type. Both cohort seedlings were altered when rodents were present compared to control treatments. In Cohort 1, rodents adversely affected seedlings of persistent tree species only in the absence of grass. In Cohort 2, seedlings of persistent tree species were decimated by rodents in the absence or presence of grass. In both cohorts, seedlings of persistent species established better in grass treatments, while seedlings of pioneer tree species were strongly suppressed. Tree species seed mass positively correlated with seedling establishment across all treatments except no grass–rodent treatments. Strong suppression of tree seedlings by rodents (Sigmodon toltecus) is a novel result in tropical land recently released from agriculture. One implication is that selective foraging by rodents on large-seeded persistent tree species may be facilitated by the removal of grass. Another implication is that temporary rodent control in pastures may permit higher establishment of deep-forest persistent species.

在热带牧场中，草被认为是重要的再生屏障，但对啮齿动物和啮齿动物与草类的相互作用的影响尚不甚了解。作为有选择的觅食者，啮齿动物可以塑造树木群落，在更新热带景观时调节生物多样性。我们利用完全交叉的双向因子设计来检验草，啮齿动物及其相互作用对牧场栖息地树木幼苗生长的影响。在实验框架内，我们分别跟踪了两个单独的树队列，为期1年。使用多个队列来更好地表示演替树种的变异和响应。树木物种的特征是种子质量呈梯度变化，并具有先驱或持续演替类型。与对照组相比，当有啮齿动物时，这两个队列的幼苗都发生了变化。在队列1中，仅在没有草的情况下，啮齿动物才对持久树种的幼苗产生不利影响。在同类研究2中，在没有草或没有草的情况下，啮齿动物会破坏持久树种的幼苗。在这两个队列中，持久性树种的幼苗在草处理中均能更好地建立，而先锋树种的树种则受到强烈抑制。在所有处理中，除无草鼠处理外，树木物种的种子质量与幼苗生长呈正相关。啮齿动物对树苗的强烈抑制作用（而先锋树种的幼苗被强烈抑制。在所有处理中，除无草鼠处理外，树木物种的种子质量与幼苗生长呈正相关。啮齿动物对树苗的强烈抑制作用（而先锋树种的幼苗被强烈抑制。在所有处理中，除无草鼠处理外，树木物种的种子质量与幼苗生长呈正相关。啮齿动物对树苗的强烈抑制作用（Sigmodon toltecus（Sigmodon toltecus）是最近从农业中释放出来的热带土地上的一个新颖成果。一个含义是，除草可以促进啮齿动物对大种子的持久树种的选择性觅食。另一个含义是，临时控制牧场中的啮齿动物可能允许建立更多的深林持久性物种。