Comparison of Soil Organic Matter (SOM) Composition in the soil column at the Biosphere 2 Tropical Rainforest
Abstract
The tropical rainforest (TRF) is an important part of Earth's biome as it contains 40% of terrestrial carbon and 33% of atmospheric carbon. Changes in soil organic matter (SOM), an essential component of carbon storage and cycling in TRF soils, can alter atmospheric inputs in the form of greenhouse gases. Therefore, it is important to understand TRF SOM composition and transformations in the face of climate variability. In preparation for a future campaign focusing on the impacts of drought on the B2 TRF biome (B2 WALD), soil organic matter was characterized using Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS). Four replicate soil cores were collected from 8 sites in the TRF biome and split into 5 depths from 0 to 75 cm in order to determine how SOM composition changes with depth. Results demonstrated that the use of biological replicates while sampling displayed a great degree of heterogeneity. Despite the heterogeneity between individual samples, upper soils were dominated by labile compounds, while deeper soils show more recalcitrant compounds. Furthermore, surface soils showed more plant inputs indicated by lignin, tannin and hydrocarbon-like compounds, where deeper soils showed microbial biomass residues in the form of proteins and lipids. These results provide a baseline characterization of depth profiles in the B2 TRF soils which allows for better prediction of SOM transformations under the effects of drought in the TRF.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B11O2189C
- Keywords:
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- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0452 Instruments and techniques;
- BIOGEOSCIENCES;
- 0454 Isotopic composition and chemistry;
- BIOGEOSCIENCES;
- 1631 Land/atmosphere interactions;
- GLOBAL CHANGE