scholarly journals Soil water regulates the control of photosynthesis on diel hysteresis between soil respiration and temperature

2016 ◽  
Author(s):  
Ben Wang ◽  
TianShan Zha ◽  
Xin Jia ◽  
Jinnan Gong ◽  
Charles Bourque ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Soil Respiration ◽  
Soil Water ◽  
Volumetric Soil Water Content ◽  
Desert Shrub ◽  
Physical Mechanisms ◽  
Relative Contribution ◽  
Diel Variations ◽  
Volumetric Soil Water

Abstract. Causes for diel hysteresis between soil respiration (Rs) and temperature remain highly controversial. Explanations for the occurrence of hysteresis have involved both biological and physical mechanisms. The specifics of these explanations, however, tend to vary with the particular ecosystem or biome being studied. This study examined the seasonal variation in diel hysteresis and its controlling factors in a desert-shrub ecosystem in northwest (NW) China. The study was based on continuous measurements of Rs, air temperature (Ta), soil temperature at the surface and below (Tsurf and Ts), volumetric soil water content (SWC), and photosynthesis over a year 2013. Trends in diel Rs were observed to vary with SWC over the growing season. Diel variations in Rs were more closely associated with Tsurf than with photosynthesis as SWC increased, leading to Rs being in phase with Tsurf, particularly when SWC > 0.08 m3 m−3. However, as SWC decreased below 0.08 m3 m−3, diel variations in Rs were more closely related to variations in photosynthesis, leading to a pronounced diel hysteresis and asynchronicity between Rs and Tsurf. It was indicated that SWC regulates the relative control between photosynthesis and temperature on diel Rs by changing the relative contribution of autotrophic and heterotrophic respiration to total Rs, and thus, causing seasonal variation in diel hysteresis between Rs and temperature. Our findings highlight the importance of biologically-based mechanisms and the role of SWC in regulating diel hysteresis between Rs and temperature.

scholarly journals Soil water regulates the control of photosynthesis on diel hysteresis between soil respiration and temperature in a desert shrubland

2017 ◽  
Vol 14 (17) ◽  
pp. 3899-3908 ◽  
Author(s):  
Ben Wang ◽  
Tian Shan Zha ◽  
Xin Jia ◽  
Jin Nan Gong ◽  
Charles Bourque ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Soil Respiration ◽  
Soil Water ◽  
Soil Surface ◽  
Volumetric Soil Water Content ◽  
Desert Shrub ◽  
Physical Mechanisms ◽  
Diel Variations ◽  
Degree Of Control ◽  
High Degree

Abstract. Explanations for the occurrence of hysteresis (asynchronicity) between diel soil respiration (Rs) and soil temperature (Ts) have evoked both biological and physical mechanisms. The specifics of these explanations, however, tend to vary with the particular ecosystem or biome being investigated. So far, the relative degree of control of biological and physical processes on hysteresis is not clear for drylands. This study examined the seasonal variation in diel hysteresis and its biological control in a desert-shrub ecosystem in northwest (NW) China. The study was based on continuous measurements of Rs, air temperature (Ta), temperature at the soil surface and below (Tsurf and Ts), volumetric soil water content (SWC), and photosynthesis in a dominant desert shrub (i.e., Artemisia ordosica) over an entire year in 2013. Trends in diel Rs were observed to vary with SWC over the growing season (April to October). Diel variations in Rs were more closely associated with variations in Tsurf than with photosynthesis as SWC increased, leading to Rs being in phase with Tsurf, particularly when SWC > 0.08 m3 m−3 (ratio of SWC to soil porosity  =  0.26). However, as SWC decreased below 0.08 m3 m−3, diel variations in Rs were more closely related to variations in photosynthesis, leading to pronounced hysteresis between Rs and Tsurf. Incorporating photosynthesis into a Q10-function eliminated 84.2 % of the observed hysteresis, increasing the overall descriptive capability of the function. Our findings highlight a high degree of control by photosynthesis and SWC in regulating seasonal variation in diel hysteresis between Rs and temperature.

scholarly journals Effects of volumetric soil water content and fertilizer rate on growth and baicalin accumulation in two species of Scutellaria

2018 ◽  
Vol 10 (6) ◽  
pp. 97-105 ◽  
Author(s):  
Morgan Amanda ◽  
Joseph Pearson Brian ◽  
Shad Ali Gul ◽  
Moore Kimberly ◽  
Osborne Lance
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Fertilizer Rate ◽  
Volumetric Soil Water Content ◽  
Volumetric Soil Water

scholarly journals Soil moisture modifies the response of soil respiration to temperature in a desert shrub ecosystem

2014 ◽  
Vol 11 (2) ◽  
pp. 259-268 ◽  
Author(s):  
B. Wang ◽  
T. S. Zha ◽  
X. Jia ◽  
B. Wu ◽  
Y. Q. Zhang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Respiration ◽  
Seasonal Cycle ◽  
Northwest China ◽  
Interactive Effects ◽  
Co2 Efflux ◽  
Diel Variation ◽  
Desert Ecosystems ◽  
Volumetric Soil Water Content ◽  
Desert Shrub

Abstract. The current understanding of the responses of soil respiration (Rs) to soil temperature (Ts) and soil moisture is limited for desert ecosystems. Soil CO2 efflux from a desert shrub ecosystem was measured continuously with automated chambers in Ningxia, northwest China, from June to October 2012. The diurnal responses of Rs to Ts were affected by soil moisture. The diel variation in Rs was strongly related to Ts at 10 cm depth under moderate and high volumetric soil water content (VWC), unlike under low VWC. Ts typically lagged Rs by 3–4 h. However, the lag time varied in relation to VWC, showing increased lag times under low VWC. Over the seasonal cycle, daily mean Rs was correlated positively with Ts, if VWC was higher than 0.08 m3 m−3. Under lower VWC, it became decoupled from Ts. The annual temperature sensitivity of Rs (Q10) was 1.5. The short-term sensitivity of Rs to Ts varied significantly over the seasonal cycle, and correlated negatively with Ts and positively with VWC. Our results highlight the biological causes of diel hysteresis between Rs and Ts, and that the response of Rs to soil moisture may result in negative feedback to climate warming in desert ecosystems. Thus, global carbon cycle models should account the interactive effects of Ts and VWC on Rs in desert ecosystems.

scholarly journals Postharvest Performance of ‘Pacific Rose™’ Apple Grown Under Partial Rootzone Drying

HortScience ◽  
2008 ◽  
Vol 43 (3) ◽  
pp. 952-954 ◽  
Author(s):  
Jorge A. Zegbe ◽  
M. Hossein Behboudian ◽  
Brent E. Clothier ◽  
Alexander Lang
Keyword(s):  
Weight Loss ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Quality Attributes ◽  
Volumetric Soil Water Content ◽  
Lower Weight ◽  
Partial Rootzone Drying ◽  
Two Sides ◽  
Volumetric Soil Water

Quality and storability of ‘Pacific Rose™’ apple grown under partial rootzone drying (PRD) were studied over 2 years. The treatments were commercial irrigation (CI) and PRD, which were applied by watering one side of the tree row throughout the season (Expt. 1) or by alternating irrigation between two sides of the tree row when volumetric soil water content ranged between 0.18 and 0.22 m3·m−3 (Expt. 2). The PRD and CI fruit had similar quality attributes at harvest and after storage except that the former had lower weight loss during storage in Exp. 1 and a lower firmness after storage in Exp. 2. Compared with CI, PRD saved water by 0.15 mega liters per hectare in Exp. 1 and by 0.14 mega liters per hectare in Exp. 2. We recommend PRD for humid environments similar to ours.

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