TreeTOP: Plant experimental platforms in canopy space

Forest canopies are known to create distinct microclimatic conditions that significantly influence plant growth, species interactions, and ecosystem processes. However, accessing these canopies for research has been a challenge due to their difficult-to-reach nature. In response, a team has developed TreeTOP, a standardized experimental platform designed to provide researchers with easy access to tree canopies for manipulative ecological experiments.

TreeTOP is composed of lightweight aluminum frames that are installed in mature trees without causing any harm. These frames allow potted plants to be positioned at three different heights within the canopy: ground level, shade canopy, and sun canopy. The platform was tested in two settings, one with a canopy crane, grid power, and fully automated irrigation, and the other built by certified tree climbers equipped with an autonomous solar-powered, battery-operated irrigation system.

Both installations successfully replicated the characteristic canopy microclimatic gradients, such as increasing light availability, daytime air temperatures, and thermal extremes with height. Remarkably, despite the differing infrastructures, both implementations generated similar microclimatic patterns, demonstrating that standardized canopy experiments can be carried out in forests with or without permanent canopy access.

By opening canopy space for manipulative experiments, TreeTOP offers a transferable framework for studying various aspects of plants, including their performance, phenology, species interactions, and microbiome assembly, all within the context of realistic forest conditions.