Ant Resource Detection Distance at the Caxiuana National Forest in Brazil 2017-2018

Environmental change scenarios of low precipitation forecast species loss in tropical regions. These losses can affect generalist species that provide important ecosystem services, such as controlling the rate at which nutrients become available for uptake by other organisms in tropical forests. Here, we use a long-term rainwater exclusion experiment in primary Amazonian rainforest to test whether induced water stress affects the detection distance of food resources (baits) in a generalist ant guild (number of colonies, richness, and composition) that remove resources on the ground. We found that (i) overall the distance of resource removal by generalist ants did not change with drought; (ii) however, comparing ant species that occurred in drought-induced and control environments, workers walked shorter distances in the drought habitat; (iii) the number of resources detected by ant colonies in the drought-induced habitat decreased by 50%. Although generalist ants are considered resilient to habitat disturbance, the effect of reduced rainfall can negatively affect the services mediated by them. The rate of removal and consumption of resources in tropical forests may be related to abundance of generalist ants; losses in both nest density and walking distances may cause cascading effects on ecosystem processes and the services they mediate.

低降水驱动的环境变化情景会导致热带地区物种丧失。此类物种丧失会影响那些提供重要生态系统服务的广食性物种（generalist species），例如调控热带森林中养分可供其他生物吸收利用的速率。本研究依托亚马孙原生雨林中的长期减雨实验（rainwater exclusion experiment），探究诱导水分胁迫（induced water stress）是否会影响在地面取食资源的广食性蚁类功能群（generalist ant guild，包括蚁群数量、物种丰富度及物种组成）对食物资源（baits，诱饵）的探测距离。研究结果显示：（1）总体而言，广食性蚁类移除资源的距离并未随干旱发生显著变化；（2）但对比干旱胁迫组与对照组的蚁类物种，干旱生境中的工蚁移动距离更短；（3）干旱胁迫生境中蚁群探测到的食物资源数量下降了50%。尽管广食性蚁类被认为对栖息地干扰具有较强抗性，但降水减少的影响仍会对其介导的生态系统服务产生负面效应。热带森林中资源移除与消耗的速率或与广食性蚁类的丰度相关；蚁群密度下降及工蚁移动距离缩短，可能会对生态系统过程及其介导的服务产生级联效应。