Ants in an Induced Drought Experiment at the Caxiuana National Forest in Brazil 2011-2012

Environmental change scenarios caused by low precipitation forecast species loss in tropical regions. We used one year of data from a rainwater exclusion experiment in primary Amazonian rainforest to test whether induced water stress, and covarying changes in humidity, soil respiration, and tree species richness, size, and total biomass and its diversity affected species richness and composition (relative abundance) of ground-dwelling ants. Induced drought reduced ant richness, whereas increased humidity and variability in biomass increased it. Species composition differed between control and rainfall-excluded plots. Occurrence of many ant species was strongly reduced, but some generalist groups of ants were favored by induced drought. The expected loss of ant species and changes in ant species composition in tropical forests likely will lead to cascading effects on ecosystem processes and services they mediate.

降水不足引发的环境变化情景，被预测将导致热带地区出现物种丧失。本研究利用亚马孙原生雨林内一项减雨试验（rainwater exclusion experiment）获取的为期一年的观测数据，检验了人工诱导的水分胁迫，以及与之协同变化的湿度、土壤呼吸、树木物种丰富度、植株体量、总生物量及其多样性的改变，是否会对地表蚂蚁（ground-dwelling ants）的物种丰富度与群落组成（相对多度，relative abundance）产生影响。人工诱导的干旱降低了蚂蚁物种丰富度，而湿度升高与生物量变异性增大则会提升蚂蚁物种丰富度。对照样地（control plots）与减雨样地（rainfall-excluded plots）的蚂蚁群落组成存在显著差异。多数蚂蚁物种的出现频次大幅降低，但部分广食性蚂蚁类群（generalist groups）会在人工诱导的干旱环境中获得生存优势。热带森林中预期出现的蚂蚁物种丧失与群落组成变化，可能会对其所介导的生态系统过程与服务产生级联效应（cascading effects）。