Biosphere-atmosphere interactions of cryptogamic communities at the Amazon Tall Tower Observatory (ATTO) and their relevance across spatial scales.
Duration: 15.08.2022 - 15.02.2026 Sponsor: FWF (Fonds z. Förderung d. wissensch. Forschung)
Larger Research Context: The Amazon Basin hosts the largest contiguous tropical forest area and represents a stabilizing factor in the Earth's climate system. Cryptogamic communities consisting of cyanobacteria, algae, fungi, lichens, and mosses are ubiquitous, yet there is little study of their functional roles in atmospheric processes and biogeochemical cycles. Hypotheses: The research program I present is based on the following five hypotheses. Cryptogamic communities (1) cover a large portion of the trunks and branches of Amazonian trees, and therefore the processes they regulate may have substantial effects; (2) can store large amounts of water and their water content changes rapidly depending on the local microclimate, contributing significantly to the total evapotranspiration of the tropical rainforest; (3) contribute significantly to the carbon cycle and its storage; (4) release bioaerosols, depending on local environmental conditions, affecting local atmospheric conditions; (5) exchange volatile organic components (VOCs), affecting regional atmospheric chemistry. While four key functional processes will be investigated using hypotheses (2)-(5), classification and mapping of cryptogamic communities (1) will allow quantification of these processes. Methods: Classification and mapping of cryptogamic communities will be based on drone-based digital images classified by object-based image analysis using artificial intelligence supported by morphological and molecular identification methods. The water storage capacity of cryptogams and the fluctuation of stored water will be analyzed using long-term microclimate measurements combined with gravimetric measurements. The role of cryptogamic communities in the carbon cycle and its storage will be analyzed using CO2 gas exchange, combined with microclimate measurements and 14C analyses. The bioaerosol emission of individual organisms will be measured with a particle counter in a measurement setup established for this purpose and combined with the mapping data of the organism groups to predict the bioaerosol emission and their composition. Their mixing in the atmosphere is characterized using a particle detection device that acquires height profiles on an automated instrument elevator at the ATTO tower. Volatile organic components will be measured using chamber and field measurements with a PTR time-of-flight spectrometer. Novelty: This project will provide entirely new and globally relevant insights regarding the importance of cryptogamic communities in water and carbon cycling and in relation to the release of bioaerosols and volatile organic components in the Amazon region. A first detailed survey of the extent and composition of cryptogamic communities will be novel in itself and will allow quantification of their influence on atmospheric processes and biogeochemical cycles. Key Scientists Involved: As part of this truly interdisciplinary project, Thomas Pock (TU Graz, Austria) will be involved in the AI-assisted image analysis and Susan Trumbore (Max Planck Institute for Biogeochemistry, Jena, Germany) in the 14C analyses. The bioaerosol studies will be performed in close collaboration with Christopher Pöhlker (Max Planck Institute for Chemistry, Mainz, Germany) and the measurements of volatile organic components with Jonathan Williams (Max Planck Institute for Chemistry).