Programa de Pós-Graduação em Ecologia, Department of Animal Biology, Institute of Biology, University of Campinas (UNICAMP), P.O. Box 6109, Campinas, SP, 13083-970, Brazil.
Center for Environmental Studies and Research (NEPAM), University of Campinas (UNICAMP), Campinas, SP, 13083-867, Brazil.
Oecologia. 2022 May;199(1):205-215. doi: 10.1007/s00442-022-05179-8. Epub 2022 May 8.
Environmental heterogeneity is a key component in explaining the megadiversity of tropical forests. Despite its importance, knowledge about local drivers of environmental heterogeneity remains a challenge for ecologists. In Neotropical forests, epiphytic tank bromeliads store large amounts of water and nutrients in the tree canopy, and their tank overflow may create nutrient-rich patches in the soil. However, the effects of this nutrient flux on environmental heterogeneity and plant community structure in the understory remain unexplored. In a Brazilian coastal sandy forest, we investigated the effects of the presence of epiphytic tank bromeliads on throughfall chemistry, soil chemistry, soil litter biomass, light, and seedling community structure. In the presence of epiphytic tank bromeliads, the throughfall nitrogen concentration increased twofold, the throughfall phosphorus concentration increased threefold, and the soil patches had a 3.96% higher pH, a 50% higher calcium concentration, and 11.88% less light. By altering the availability of soil resources and conditions, the presence of bromeliads partially shifted the available niche spaces for plant species and indirectly affected the structure of the seedling communities, decreasing their diversity, density, and biomass. For the first time, we showed that the presence of tank bromeliads in the canopy can create characteristic soil patches in the understory, affecting the structure of seedling communities via fertilization. Our results reveal a novel local driver of environmental heterogeneity, reinforcing and expanding the key role of tank bromeliads both in nutrient cycling and plant community structuring of Neotropical coastal sandy forests.
环境异质性是解释热带森林物种多样性的关键因素。尽管其重要性不言而喻，但生态学家对于环境异质性的本地驱动因素的了解仍然具有挑战性。在新热带森林中，附生的水槽凤梨在树冠层中储存了大量的水和养分，其水槽溢出物可能会在土壤中形成富营养斑块。然而，这种养分通量对林下环境异质性和植物群落结构的影响仍未得到探索。在巴西沿海沙质森林中，我们调查了附生的水槽凤梨的存在对穿透雨化学性质、土壤化学性质、土壤凋落物生物量、光照和幼苗群落结构的影响。在有附生水槽凤梨的地方，穿透雨的氮浓度增加了两倍，磷浓度增加了三倍，而土壤斑块的 pH 值高 3.96%，钙浓度高 50%，光照少 11.88%。通过改变土壤资源和条件的可利用性，凤梨的存在部分改变了植物物种的可用生态位空间，并间接地影响了幼苗群落的结构，降低了其多样性、密度和生物量。这是首次表明，树冠中水槽凤梨的存在可以在林下创造出具有特征性的土壤斑块，通过施肥对幼苗群落的结构产生影响。我们的研究结果揭示了一种新的环境异质性的本地驱动因素，强化并扩展了水槽凤梨在新热带沿海沙质森林的养分循环和植物群落结构中的关键作用。
