Understanding forest regeneration in bracken-dominated areas of tropical montane forest: a trait-based approach

热带山地森林是世界上最重要的生物多样性热点之一。然而，由于土地利用的变化，特别是人为火灾造成的变化，许多林区变得高度分散。剩下的森林残留物被以蕨类植物为主的强烈干扰的生境所包围。由于蕨类通常长时间和大面积地主导植被，扰乱森林演替和生态系统服务，迫切需要以科学为基础的战略，以加速森林更新。我们将结合玻利维亚安第斯山脉以蕨类植物为主的热带山地群落的观测和实验研究，以：a)确定主要的非生物和生物filter，解释物种共存和森林更新期间的表现；b)确定可以与蕨类植物共存的树种的功能特征。我们的项目分为四个工作包(WP)：在WP1中，我们将研究火灾以来不同树龄地区树种的自然更新，以预测可能的时间模式，以及使用时序方法(空间换时间)来表征环境条件和群落功能特征的变化。为了验证我们的假设，即种子限制，而不是建立限制，是推迟蕨类为主地区森林恢复的最重要的过滤器，我们将通过实验评估与更新相关的植物-植物相互作用(WP2：竞争、促进)和植物-动物相互作用(WP3：种子传播)。在WP2中，我们将评估不同功能特性的本地树种在不同实验蕨菜处理下的表现，并测试蕨菜对普通花园植物发育的潜在化感作用。在第三期工程中，我们会评估鸟类和蝙蝠的种子散播效能，以及栖息地和蝙蝠栖息地在增加种子散播和幼苗招募方面的潜在价值。在WP4中，我们将利用结构方程模型，通过考虑非生物和生物变量对热带山地树种生活史不同阶段的直接和间接影响，研究热带山地树种招募的主要瓶颈。最后，在一种综合的方法中，我们的数据将被结合起来，形成基于生态特征的模型，根据蕨类的存在和气候变化的预测来预测物种丰富度，并测试替代的群落路径。我们的项目将大大提高我们对热带山地森林更新动态的了解，并将为加快蕨类为主地区的森林恢复提供必要的信息，这些地区在整个热带地区都很常见。

Tropical montane forests are among the most important biodiversity hotspots of the world. However, many forest areas have become highly fragmented due to land-use change, especially caused by human-induced fires. The remaining forest remnants are surrounded by strongly disturbed habitats dominated by bracken fern (Pteridium spp.). Since bracken usually dominates the vegetation for long periods and across large areas, disrupting forest succession and ecosystem services, science-based strategies to accelerate forest regeneration are urgently needed. We will combine observational and experimental studies in tropical bracken-dominated montane communities of the Bolivian Andes in order to: a) identify the major abiotic and biotic filters that explain species coexistence and performance during forest regeneration; b) determine the functional traits of the tree species that can coexist with bracken. Our project is structured in four work packages (WP): In WP1, we will study the natural regeneration of tree species in areas with different ages since fire to predict the likely temporal pattern, as well as characterize the changes in environmental conditions and functional traits of the community, using a chronosequence approach (space-for-time substitution). To test our hypothesis that seed limitation, rather than establishment limitation, is the most important filter delaying forest recovery in bracken-dominated areas, we will experimentally assess regeneration-related plant-plant interactions (WP2: competition, facilitation) and plant-animal interactions (WP3: seed dispersal). In WP2, we will evaluate the performance of native tree species with different functional traits under different experimental bracken treatments and test the potential allelopathic effects of bracken on plant development in a common garden. In WP3, we will assess seed dispersal effectiveness of birds and bats, and the potential value of perches and bat roosts to increase seed dispersal and seedling recruitment. In WP4, we will study the main bottlenecks for the recruitment of tropical montane tree species by considering direct and indirect effects of abiotic and biotic variables on different stages in their life cycles, using structural equation models. Finally, in an integrative approach, our data will be combined to form ecological trait-based models that predict species abundances and test alternative community pathways according to bracken presence and climate change predictions. Our project will substantially enhance our understanding of the dynamics of tropical montane forest regeneration, and will provide essential information for accelerating forest restoration in bracken-dominated areas, which are common throughout tropical regions.