Past aridity's effect on carbon mineralization potentials in grassland soils
<p>Mineralization potential is a key property for assessing carbon substrate's degradability and mineralization in biogeochemical models and studies. While mineralization potential is widely examined under controlled conditions, whether and how it is influenced by the past aridity of samp...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-09-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/16/3605/2019/bg-16-3605-2019.pdf |
| Summary: | <p>Mineralization potential is a key property for assessing
carbon substrate's degradability and mineralization in biogeochemical models
and studies. While mineralization potential is widely examined under
controlled conditions, whether and how it is influenced by the past aridity
of sample's origins remain poorly constrained, which is important for an
accurate assessment and prediction of future <span class="inline-formula">CO<sub>2</sub></span> emissions. Here we
collect topsoils and subsoils from different aridity regimes along a 2100 <span class="inline-formula">km</span>
grassland transect of northern China and conduct a 91 <span class="inline-formula">d</span> decomposition
experiment with and without the addition of <span class="inline-formula"><sup>13</sup>C</span>-labeled leaf litter
under controlled temperature and moisture. <span class="inline-formula">CO<sub>2</sub></span> release from both soil
organic carbon (SOC) and fresh litter is measured, along with microbial
biomass, extracellular enzyme activities, and soil and mineral properties. We
find that neither microbial carbon use efficiency nor biomass-normalized
metabolic quotient (<span class="inline-formula"><i>q</i>CO<sub>2</sub></span>) is related to the aridity of sampling sites.
However, both fresh litter and SOC display the highest mineralization
potentials in soils originating from the driest site. Using pathway
analysis, we demonstrate that past aridity's effect is mediated by
differential mechanisms for substrates of varied complexity. While microbial
biomass plays a more important role in the decomposition of fresh litter,
enzyme-catalyzed extracellular reactions predominantly govern the
mineralization of SOC. Our findings provide novel evidence on the mechanisms
underlying past aridity's effect on the mineralization potentials of organic
matter with different qualities, which has significant implications for
assessing and modeling decomposition in different aridity regimes.</p> |
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| ISSN: | 1726-4170 1726-4189 |