Microclimatic measurement setup to assess the physiological activity patterns of epiphytic cryptogamic communities in the Amazon rainforest

Cryptogamic communities (CC) consist of photoautotrophic lichens, bryophytes, algae, and cyanobacteria, as well as heterotrophic fungi, bacteria, and archaea. They colonize soils, rocks, tree stems and leaves across the globe. In the Amazon rainforest, they cover large amounts of tree stem surfaces and potentially play key roles in biogeochemical cycling in these regions. These processes include carbon and nitrogen fixation, as well as water and nutrient cycling. In addition, they emit bioaerosols and are involved in the exchange of volatile organic compounds. Since these processes are driven by the availability of water, light and temperature, knowledge of these parameters is essential in order to quantify these processes at ecosystem scales.

Here we present a novel microclimate sensor system that has been installed on eight trees in two different forest types in the Amazon rainforest. On each tree, sensors measuring temperature, light intensity, and water content of representative bryophytes at 10-minute intervals were installed at three different heights (near ground, at the main stem and in the canopy) in two expositions (north and south). Measurements are sent wirelessly from each tree to a server where data are post-processed, automatically checked for validity and sent to a cloud storage for further analysis. First measurement results of the system provide insights into day and night patterns as well as the hydration status of the investigated bryophyte communities depending on the colonized habitat (height, exposition). Long-term measurements and analyses will improve our understanding of the dynamics of the physiological processes of CC in times of changing climatic conditions, and will serve as a foundation for the upscaling of functional processes.