Figure - available from: Frontiers in Plant Science
This content is subject to copyright.
Seasonal dynamics of Rs (A–C), Ra (D–F), and Rh (G–I) in 2017, corresponding to PFTs of G, S, and GS, respectively. Letters, arranged in the same vertical order as the points they refer to, indicated significant differences (a, identical to controls). For clarity, only significant differences were depicted. Data are mean ± 1SE.
Source publication
Globally, droughts are the most widespread climate factor impacting carbon (C) cycling. However, as the second-largest terrestrial C flux, the responses of soil respiration (Rs) to extreme droughts co-regulated by seasonal timing and PFT (plant functional type) are still not well understood. Here, a manipulative extreme-duration drought experiment...
Similar publications
Drought timing determines the degree to which dry events impact ecosystems, with the ability of key processes to withstand change differing between drought periods. Findings indicate that drought timing effects vary across ecosystems, with few studies focusing on alpine grasslands. We conducted a mesocosm experiment using small grassland monoliths...
Citations
... In our experiment, drought relatively reduced Rs by 3.4%. This was consistent with previous studies on the semi-arid grassland ecosystem in Inner Mongolia and the Mediterranean ecosystem [14,49,[51][52][53]. In arid and semi-arid ecosystems, water availability is the primary factor influencing the productivity and carbon source for Rs. ...
Elevated temperature and frequent drought events under global climate change may seriously affect soil respiration. However, the underlying mechanism of the effects of warming and drought on soil respiration is not fully understood in the context of the Loess Plateau. This study examined the response of soil respiration (Rs) to multiple factors, including warming (W), drought (P), and their interaction (WP), in the semi-arid grassland of the Loess Plateau in Northwest China. The research period was from May to November 2022, with an open-top heating box used for warming and a rain shelter used for drought. The results showed the following: (1) Rs ranged from 1.67 μmol m−2 s−1 to 4.77 μmol m−2 s−1, with an average of 3.36 ± 0.07 μmol m−2 s−1. The cumulative soil carbon flux ranged from 500.97 g C·m−2 to 566.97 g C·m−2, and the average cumulative soil respiration was 535.28 ± 35.44 g C·m−2. (2) Warming increased Rs by 5.04 ± 3.11%, but drought inhibited Rs by 3.40 ± 3.14%, and the interaction between warming and drought significantly reduced soil respiration by 11.27 ± 3.89%. (3) The content of particulate organic carbon (POC), dissolved organic carbon (DOC), soil organic carbon (SOC), and readily oxidized carbon (ROC) decreased with the increased soil depth. ROC after W and WP treatments was significantly higher than that of the control, and POC after P treatment was significantly higher than CK (p < 0.05). (4) The seasonal variation of soil respiration was positively correlated with soil temperature, soil water content, plant height, and leaf area index (p < 0.05), but the response rules differed during different regeneration periods. Soil water content; soil water content and leaf area index; and soil water content, soil temperature, and leaf area index were the factors that regulated the variation in soil respiration in the first, second, and third regeneration periods, respectively. These results clearly showed the limiting effect of drought stress on the coupling between temperature and soil respiration, especially in semi-arid regions. Collectively, the variations in soil respiration under warming, drought, and their interactions were further regulated by different biotic and abiotic factors. Considering future warming, when coupled with increased drought, our findings indicate the importance of considering the interactive effects of climate change on soil respiration and its components in arid and semi-arid regions over the next decade.
... Although several studies have been conducted to investigate the effects of drought on Rs, the results of previous studies have been variable, including increasing (Liu et al., 2016;Chu et al., 2022), decreasing (Meng et al., 2020;Qian et al., 2022), and unchanging Xi et al., 2022) trends. These inconsistent and frequently contradictory results limit our understanding and prediction of feedbacks between soil C emissions and climate change. ...
... The response of Rs and its components to drought is synergistically regulated by multiple biotic and abiotic factors, such as soil temperature (Ts), soil volumetric water content (VWC), plant activity, and substrate availability Meng et al., 2020;Qian et al., 2022). These factors vary seasonally in temperate climatic regions; hence, there are seasonal differences in the response patterns of soil respiration and its components to drought Qian et al., 2022). ...
... The response of Rs and its components to drought is synergistically regulated by multiple biotic and abiotic factors, such as soil temperature (Ts), soil volumetric water content (VWC), plant activity, and substrate availability Meng et al., 2020;Qian et al., 2022). These factors vary seasonally in temperate climatic regions; hence, there are seasonal differences in the response patterns of soil respiration and its components to drought Qian et al., 2022). This is especially true in spring and summer, when more than half of the plant growing season is distributed in spring and summer (Ning et al., 2020;Qian et al., 2022). ...
Climate change has increased the intensity and frequency of seasonal droughts, which could fundamentally affect the terrestrial carbon (C) cycle. However, as the second-largest terrestrial C flux, soil respiration (Rs) and its heterotrophic (Rh) and autotrophic (Ra) components in response to seasonal drought are unclear. To investigate the effect of seasonal drought on the patterns and mechanisms of Rs and its components, a two-year continuous Rs measurement experiment was conducted in typical rain-fed managed alfalfa (Medicago sativa L.) fields on the Loess Plateau in China. The results showed that the ranges of Rs, Rh and Ra in the four seasons of managed alfalfa fields on the Loess Plateau were 0.45-3.70, 0.13-2.27, and 0.33-2.14 μmol m − 2 s − 1 , respectively. There was no significant difference in the average annual Rs between the two years (P > 0.05). Both spring and summer droughts significantly decreased Rs; however, the seasonal Rh and Ra had different patterns under spring and summer droughts. Spring drought significantly reduced the seasonal Rh by 35.19 % but increased Ra by 20.35 %. In contrast, summer drought significantly increased the seasonal Rh by 45.51 % but decreased the Ra by 35.05 %. The differential response of Ra to seasonal drought was attributed to the opposite responses of the leaf area index (LAI) and photosynthetic rate to spring and summer drought, while Rh was related to the contrasting microorganism responses to spring drought and the pulse effect of rainfall following summer drought. Our study highlights the contrasting responses of Ra and Rh to seasonal drought. Spring drought significantly reduced the relative contribution of Rh to Rs, but summer drought increased the relative contribution of Rh to Rs. These results suggest that future increases in the frequency of summer droughts may accelerate the turnover of soil C and further affect the stability of soil C stocks in semi-arid regions.
Increasingly frequent and severe droughts are occurring in multiple seasons of a year in many dryland ecosystems , with unknown impacts on the role of drylands in cycling of methane (CH 4), a potent greenhouse gas. In particular, there is limited understanding of how drought occurring at different times within the growing season regulates biological CH 4 uptake, and how these responses are mediated by plant community composition. Here, we quantify how drought timing and plant community composition regulate CH 4 uptake in a semiarid grassland. We employ a field experiment in which droughts were imposed in early, middle, or late growing season in three different communities (two graminoids, two shrubs and their mixture), respectively. All three droughts increased CH 4 uptake, but the effect size and pathway varied with seasonal timing. Early and middle drought increased CH 4 uptake through increasing both soil pomA abundance and diffusivity resulting from reduced soil water content (SWC), while late drought increased CH 4 uptake only by reducing SWC. Overall, early drought had the least positive effects on CH 4 uptake because it excluded the least precipitation and therefore had smaller impacts on SWC. Besides, plant composition did not affect CH 4 uptake under normal environment but regulated CH 4 uptake in response to droughts due to different response of plant composition to droughts. Early and middle drought had larger positive effects on CH 4 uptake in shrub communities than the other two communities, consistent with larger reductions in SWC and larger increases in pomA abundance, respectively. In contrast, late drought had consistent effects on CH 4 uptake across three communities. Our results suggest that the magnitude and pathways of extreme drought effects on CH 4 uptake are strongly co-regulated by seasonal timing and plant composition.
