Acaí plantation near Humaitá, BrazilECORESPIRA-AMAZON is the first Brazilian-German project attempting to representatively determine soil respiration and soil chemistry on terra firme (non inundated land) in the region, always juxtaposing forested land with post-forest land use in the Amazon basin. The key focus lies on locations around Manaus (Central Amazonas) and in southern Amazonas (from Apuí to Boca do Acre).

The very fast turnover times of organic matter in inner tropical rainforest environments and the particular ecological role of the Amazon forest biome (water recycling, oxygen production, biodiversity hotspot, climate system tipping element, etc.) motivate this project. We seek answers and solutions for better sustainable management of the systems. Recent European experience has shown that modelling does not yet deliver satisfactory answers, neither on element pool sizes nor on soil and ecosystem respiration (Oertel et al. 2016).

In this joint project with Brazilian (Embrapa, IPAAM, UFAM and INPA) and German (TUBAF) scientists, both topics are targeted and shall complement the longer-term commitment of the Brazilian team.

Phase 1: The pilot project (February/March 2016; rainy season) focused on twelve locations: six in central Amazonas near Manaus, another six in southern reaches of the basin Amazonas, bordering Rondônia and Acre. Phase 1 additionally served as training ground for assessing measuring and sampling time as well as for team building.

Phase 2: Fieldwork in July and August 2016 (dry season) enhanced the database. In addition to the previous twelve locations, we included the biosphere reserve Adolfo Ducke near Manaus. As before, soil and litter samples were taken next to gas samples.

Phase 3: 12 locations were re-visited in February and/or March 2017 (Lábrea was inaccessible at the time). We verified previously obtained results, filled data gaps and performed reproducibility tests.

The project was immensely fortunate inasmuch as we could cover a full range of conditions from extreme draught (July and August 2016) via a modest rainy season (like a normal dry season in February and March 2016) to a wet rainy season (February and March 2017) – allowing for the characterization of extreme conditions on both sides of the spectrum as much as of average conditions.

We see intraanual (seasonal) dynamics not only in respiration but also in soil chemistry. Distinct differences emerge between forested sites and deforested ones – indepdent of the subsequent land use.

With Stefan Erasmi and Karl Heyer (Göttingen University), Frank Keppler (Biogeochemistry, University of Heidelberg) and Katharina Lenhart (Biogeochemistry, Gießen University) our team grew. We use remote sensing information and study additional processes that help discern soil microbial and fungal activities. Data from all materials are steadily coming in. A more robust and reliable database for soil respiration and soil geochemical data has been built up; we now work on publishing results.

A short field phase in February and March 2018 will study first effects of renaturation (reforesting) of pasture land near Boca do Acre, Amazonas.