Understanding different dominance patterns in western Amazonian forests

Dominance of neotropical tree communities by a few species is widely
documented, but dominant trees show a variety of distributional patterns
still poorly understood. Here, we used 503 forest inventory plots (93,719
individuals ≥ 2.5 cm diameter, 2,609 species) to explore the relationships
between local abundance, regional frequency, and spatial aggregation of
dominant species in four main habitat types in western Amazonia. Contrary
to the widely supported positive abundance-occupancy relationship in
ecology, we found that among dominant Amazonian tree species, there is a
strong negative relationship between local abundance and regional
frequency and/or spatial aggregation across habitat types. Our findings
suggest an ecological trade-off whereby dominant species can be locally
abundant (local dominants) or regionally widespread (widespread
dominants), but rarely both (oligarchs). Given the importance of dominant
species as drivers of diversity and ecosystem functioning, unraveling
different dominance patterns is a research priority to direct conservation
efforts in Amazonian forests.

新热带区树木群落（neotropical tree communities）由少数物种主导的现象已被广泛记录，但优势树种所展现的多样分布格局仍未得到充分阐释。本研究依托亚马逊西部4种主要生境类型中的503块森林调查样地（共记录93719株直径≥2.5厘米的植株，涵盖2609个物种），探究了优势树种的本地多度、区域频度与空间聚集度之间的关联。与生态学领域广为认可的多度-占有量正相关关系相悖，本研究发现，在亚马逊优势树种中，本地多度与区域频度和/或跨生境空间聚集度之间存在显著负相关关系。本研究结果揭示了一种生态权衡机制：优势树种要么具备较高的本地多度（本地优势种），要么拥有较广的区域分布（广布优势种），但极少同时兼具这两种特征（寡占种，oligarchs）。鉴于优势树种作为生物多样性与生态系统功能驱动因子的重要性，厘清不同的优势种分布格局是指导亚马逊森林保护工作的优先研究方向。