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Rainfall frequency and soil water availability regulate soil methane and nitrous oxide fluxes from a native forest exposed to elevated carbon dioxide
Author(s) -
Martins Catarina S. C.,
Nazaries Loïc,
DelgadoBaquerizo Manuel,
Macdonald Catriona A.,
Anderson Ian C.,
Singh Brajesh K.
Publication year - 2021
Publication title -
functional ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 154
eISSN - 1365-2435
pISSN - 0269-8463
DOI - 10.1111/1365-2435.13853
Subject(s) - carbon dioxide , greenhouse gas , nitrous oxide , environmental science , methane , edaphic , ecosystem , sink (geography) , soil water , terrestrial ecosystem , carbon sink , environmental chemistry , ecology , atmospheric sciences , soil science , biology , chemistry , cartography , geology , geography
Free‐air carbon dioxide enrichment (FACE) experiments in terrestrial ecosystems have demonstrated ecological responses of key ecosystem processes to rising atmospheric carbon dioxide (CO 2 ). However, CO 2 fertilization responses in field conditions have seldom included methane (CH 4 ) and nitrous oxide (N 2 O), particularly in natural and mature forests, which are expected to have an important role in climate change mitigation. Herein, we aimed to capture the effect of elevated CO 2 (eCO 2 ; ambient vs. +150 ppm) on long‐term temporal dynamics of CH 4 and N 2 O fluxes, followed by identification of climo‐edaphic factors explaining feedback responses. To achieve this, continuous monitoring of greenhouse gas (GHG) fluxes using a manual chamber technique, over a 3‐year period was implemented in a mature dryland Eucalypt forest FACE (EucFACE) facility in Australia. The relationship between CH 4 and N 2 O fluxes with rainfall indices and soil properties was also explored since they directly impact the microbial communities in the soil responsible for CH 4 and N 2 O net emissions. Our results showed that in 3 years of eCO 2 treatment, the amount and frequency of rainfall predicted GHG emissions in this native forest. We also found a significant reduction in CH 4 sink (15%–25%) for some of the years as well as an overall treatment effect index reduction in N 2 O emissions under eCO 2 . Higher frequency of rain events with lower intensity led to highest CH 4 sink followed by lowest N 2 O emissions due to fewer wet–dry cycles. Of all the environmental variables included, soil moisture, rainfall and pH were the main predictors of net CH 4 and N 2 O emissions. Methane flux was also strongly influenced by soil texture. Our findings highlight the need to account for reduced forest CH 4 sink under eCO 2 in dryland ecosystems, which has implications for GHG budget predictions under future climate conditions. A free Plain Language Summary can be found within the Supporting Information of this article.