ATTO_Hydrostore

The Amazon Tall Tower Observatory (ATTO) is a German-Brazilian research project that investigates the complex interactions between the rainforest, the soil and the atmosphere at a virtually undisturbed site deep within the Amazon rainforest. Through long-term observation of biogeochemical cycles, the water cycle and energy flows, the aim is to gain a better understanding of the role of the Amazon rainforest in the global climate system and, in doing so, to improve the prediction of the impacts of climate and land-use changes.
To better understand the effects of increasingly extreme drought and flood events on growth, photosynthetic performance and the Amazon rainforest’s function as a carbon sink, the ‘ATTO HydroStore’ project is investigating whether, and to what extent, trees store water in their trunks and can utilise it during periods of stress. This mechanism has so far been inadequately researched; however, preliminary results from water vapour isotope analyses carried out during previous project phases suggest that the trees store water in their trunks and utilise it during the dry season.

The main activities include:

Sub-project 2.3 investigates the seasonal variation in water content and storage capacity in two tree species in each of three forest ecosystems (upland forest – terra firme, savannah forest – campinarana, floodplain forest – igapó). The study utilises electrical resistance measurements, wood cores, sap flow measurements, isotope analyses (δ¹⁸O, δ²H) and near-infrared spectroscopy (NIRS). The aim is to assess water storage and use across different timescales.
 

Sub-project 3.2 continues the ongoing monitoring of tree growth (dendrometer) and phenology, extending it to the floodplain forest. In addition, the population structure of the tree species from sub-project 2.3 is being recorded and analysed in order to reconstruct responses to historical climate extremes – such as the El Niño drought of 2023/24.