Climate factors mediate soil respiration dynamics in Mediterranean agricultural environments: an empirical approach

Abstract

Soil CO2 emissions, the result of soil respiration processes, may be essential in climate change modelling. The complex phenomenon of soil respiration is regulated by a range of mainly climate-related environmental factors. We tested the latest published empirical models in a field experiment in an agricultural soil under Mediterranean conditions. Soil respiration was monitored biweekly with a portable infrared gas analyser, and climate features were monitored for 1 year (2010–11). An additional rewetting assay (watering the soil) was done at the end of the experiment in summer when the soil water content was dry. We tested different approaches to represent the simple effect of climate factors on soil respiration and found Gaussian models to be the best. We also tested the most recent models designed to represent the synergic effects of climate factors, and our modification of the Martin and Bolstad model showed the best coefficient of determination. The results suggest that linear approaches and the use of a fixed Q10 value should be revised to represent climate and soil respiration relations, especially in high-variability environments where soil respiration variability is controlled by soil temperature and moisture interactions, while precipitation pulses induce CO2 emission peaks. Finally, our results showed that the influence of soil temperature and moisture on soil respiration is lower under Mediterranean conditions than in temperate climate types.

How do biodegradable organic residues affect soil CO2 emissions? Case study of a Mediterranean agro-ecosystem

“…The application of our modified Martin and Bolstad model suggested that in CONT soils the interaction of Ts and Ms modulated Rs, as in our previous experiment (González-Ubierna et al, 2014). BOR application modified the relative importance of the interaction between these climate variables, and the single effect of Ts was the main driver of Rs, while Ms modulated the response, as suggested by Fang and Moncrieff (2001) and Almagro et al (2009).…”

“…In González-Ubierna et al (2014) we found the Gaussian model to be the best approach for expressing single relationships between soil climate variables (temperature, moisture or RWi) and soil respiration. We also devised a modification of Martin and Bolstad's model (Martin and Bolstad, 2009) to include all these variables in a single expression:…”

“…The negative correlation between Rs and Ms in Mediterranean soils could be explained by a combination of factors: in spring and autumn, when soil water contents are high, it may be due to the partial dissolution of CO 2 in the water and its transformation into soluble hydrogen carbonate, which is then washed out of the soil profile (Rochette et al, 2004). In winter, the low TS could mask the effects of high MS, due to the clear impact of the interaction of both variables on Rs (González-Ubierna et al, 2014). Almagro et al (2009) and our latest results (González-Ubierna et al, 2014) indicated a different pattern: the relationship between Rs and Ms was negative when Ts was under 16 C, and positive when above this temperature; however in all treated soils, we found no statistical relationship between Rs and Ms when Ts was above 16 C. Daily variations confirm this finding, since it was only in summer (Ts over 16 C at dawn) that the greatest differences between treatments did not coincide with the highest Ts, but with the highest Ms.…”

Dynamics of the soil respiration response to soil reclamation in a coastal wetland

“…According to the fitted empirical equations in Tables 2 and 3, our findings indicated that the soil temperature and water content combination had a significant impact on the RS (p < 0.01). However, at the seasonal scale the www.nature.com/scientificreports/ percentages of the variance that were explained by the two-variable models were 44% at the CK site, 43% at the CT site, and 41% at the WM site (Table 3), indicating that the soil temperature and water content may not be the dominant influential factors in the study and that there are still some possible factors that impact the RS 54 . Schütt et al 55 found that, although the temperature and water content at the soil surface are the primary factors restricting RS, especially in low temperature environments, other environmental factors (such as low SOC and high soil salt) become the limiting factors when the temperature is suitable for root and microbe respiration.…”

First Insights on Soil Respiration Prediction across the Growth Stages of Rainfed Barley Based on Simulated MODIS and Sentinel-2 Spectral Indices

“…In addition, the accumulation of carbon exudates in roots as well as variation in canopy transpiration and shading through the phenological cycle creates local soil conditions modifying heterotrophic respiration processes [19]. In agricultural fields all these factors result in a high CO 2 fluxes spatial and temporal variability [20,21] which may be stronger in rainfed crops in Mediterranean climates due to the irregular distribution of rainfall and temperature [22,23].…”