Abstract
One of the greatest contemporary challenges in terrestrial ecology is to determine the impact of climate change on the world’s ecosystems. Here we investigated how wetting patterns (frequency and intensity) and nutrient additions altered microbial biomass and CO2-C loss from a semi-arid soil. South-western Australia is predicted to experience declining annual rainfall but increased frequency of summer rainfall events when soil is fallow. Agricultural soils (0–10 cm at 10 °C or 25 °C) received the same total amount of water (15 mL over 30 days) applied at different frequency; with either nil or added nitrogen and phosphorus. Smaller more frequent wetting applications resulted in less CO2-C loss (P < 0.001); with cumulative CO2-C loss 35% lower than a single wetting event. This coincided with increased microbial biomass C at 25 °C but a decline at 10 °C. Increasing nutrient availability decreased CO2-C loss only under a single larger wetting event. While bacterial and fungal abundance remained unchanged, archaeal abundance and laccase-like copper monooxidase gene abundance increased with more frequent wetting at 25 °C. Our findings suggest smaller more frequent summer rainfall may decrease CO2 emissions compared to infrequent larger events; and enhance microbial C use efficiency where sufficient background soil organic matter and nutrients are available.
Highlights
Soil is the largest terrestrial reservoir of carbon (C, 1500 Gt), containing twice as much as the atmosphere (780 Gt) and three times that in global vegetation (575 Gt)[1]
Microbial C dynamics and soil C storage are influenced by nutrient availability which may regulate the response of microbial respiration to rainfall frequency and intensity[12]
Temperature had a strong influence on soil respiration with consistently (P < 0.001) higher daily CO2-C evolved at 25 °C than at 10 °C (Fig. 2)
Summary
Soil is the largest terrestrial reservoir of carbon (C, 1500 Gt), containing twice as much as the atmosphere (780 Gt) and three times that in global vegetation (575 Gt)[1]. The majority of ecosystem models assume a roughly linear response of SOM decomposition to increased water availability[10], how shifts in rainfall patterns (timing, frequency, magnitude and duration) due to climate change impact on microbial populations and soil C dynamics remains unclear. Microbial C dynamics and soil C storage are influenced by nutrient availability which may regulate the response of microbial respiration to rainfall frequency and intensity[12]. Given the potential influence of nutrient status on microbial C dynamics as well as C storage, understanding the interactive effects of wetting frequency and nutrient availability on microbial respiration will help predict the ecosystem functioning and C sequestration potential under future climate change scenarios
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
