Different functional responses in populations of Polylepis quadrijuga (Rosaceae) as a consequence of anthropogenic disturbance

The monodominant forests of Polylepis quadrijuga, endemic to the páramos of the eastern cordillera in the Colombian Andes, are among the most threatened in South America due to fragmentation and anthropogenic degradation. Despite their role in regulating water flow and forming biodiverse, endemic biotic communities, there are few studies on their functional responses to stress caused by anthropogenic disturbance and climate change. In this study, we evaluate how six different populations of P. quadrijuga with distinct levels of anthropogenic disturbance (low and high) change 11 foliar, stem, and root functional traits. Also, the physicochemical properties of the soils were analyzed, and mycorrhizal colonization was quantified to evaluate how each population responds to the stress conditions in their vital ecosystem. The results indicated that populations with lower disturbance levels exhibit a conservative leaf trait configuration, whereas those with higher disturbance levels adopt an acquisitive strategy, potentially making them more vulnerable. Additionally, we found no functional coordination between above- and below-ground traits. The results also highlight the colonization by arbuscular mycorrhizal fungi (AMF). It is essential to develop strategies tailored to the specific needs of each population to effectively conserve this important ecosystem.

哥伦比亚安第斯山脉东科迪勒拉帕拉莫（páramos）生态系统特有的四序多蕊木（Polylepis quadrijuga）单优林，因生境破碎化与人为干扰退化，是南美洲受威胁程度最高的生态系统之一。尽管此类森林在调节水文循环、构建生物多样性丰富的特有生物群落方面发挥着关键作用，但目前针对其应对人为干扰与气候变化所引发胁迫的功能响应研究仍较为匮乏。本研究以6个受人为干扰程度（低、高）各异的四序多蕊木种群为对象，分析其11项叶、茎及根功能性状的变化规律；同时测定土壤理化性质并量化菌根定殖情况，以解析各种群在其赖以生存的生态系统胁迫环境中的响应机制。研究结果显示，低干扰种群呈现保守型叶性状组合策略，而高干扰种群则采用资源获取型策略，这或进一步提升其种群生存脆弱性。此外，本研究未发现地上与地下功能性状间存在功能协同关系，同时揭示了丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF）的定殖特征。针对各种群的特定需求制定专属保护策略，是有效保护这一重要生态系统的核心前提。