Research Background

Global warming affects the carbon exchange of ecosystems, thereby altering the carbon sequestration capacity of terrestrial ecosystems. Due to its large area and high carbon storage, the Qinghai Tibet Plateau is particularly sensitive to climate change and has become an ideal area for studying the response of ecosystem carbon cycling to climate change. However, previous experiments have focused more on warming the surface of the soil, neglecting the response of deeper soil layers to warming. The response of ecosystem carbon flux to the warming of the entire soil profile is still unclear.

Research methods:

Based on the Whole soil warming experiment established in the high-altitude grassland ecosystem of Haibei Station in Qinghai Province, this study investigates the effects of whole soil warming (up to 1 meter depth, heating to 4 ° C) on ecosystem carbon flux (including three components: total ecosystem productivity GEP, ecosystem respiration ER, and net ecosystem carbon exchange NEE, observed in situ in the field for three years from 2018 to 2020). At the same time, a database containing 48 articles was compiled to examine the general patterns of experimental warming on these fluxes through global meta-analysis.

Main research findings:

The results showed that overall soil warming increased the total ecosystem productivity (GEP) by 14% and ecosystem respiration (ER) by 11%, but had a relatively small impact on the net carbon exchange (NEE) of alpine grasslands. In the meta-analysis, warming also increased GEP (10-11%) and ER (13%), but did not change NEE. The changes in plant communities and prolonged growth seasons caused by warming may be the main reasons for the higher GEP and ER under warming, while the mutual cancellation of the two fluxes may lead to a smaller response of NEE to warming.

Figure 2: The impact of soil warming on carbon flux in alpine grassland ecosystems across the entire profile (3-year average)

In addition, there is a significant positive correlation between ecosystem carbon flux and soil temperature (0-10 cm), indicating that the higher the temperature, the stronger the total ecosystem productivity, ecosystem respiration, and net ecosystem carbon exchange processes (Figure 3).

Figure 3: The relationship between carbon flux and soil temperature and moisture (0-10 cm) in alpine grassland ecosystems

To investigate the effect of deep soil warming on soil carbon flux in this article, we recommend the SoilScope controlled evapotranspiration system solution, which is a multifunctional and novel weighing based control experimental system.

The field warming test device of this system adopts the method of warming in soil to ensure uniform warming. Realize a heating effect of 0.1 ℃ to 5.0 ℃ in a circular area with a diameter of 3 meters, with adjustable temperature and heating power of 5kw/heating zone.

By installing heating rods inside the soil to increase temperature, heat can be directly transferred to the soil. Combined with temperature control equipment, the soil temperature can be stabilized within the target range. There will be no significant temperature fluctuations caused by natural warming or other heating methods, and it is suitable for specific needs such as crop growth and soil remediation.

The heating rod can be arranged reasonably according to the size of the soil, and the heat radiates and spreads from the rod body to the surrounding areas, which can avoid local overheating or cold zones. Compared to surface heating, it can achieve synchronous warming of deep soil and ensure overall temperature consistency of the soil.

After being powered on, the heating rod can quickly generate heat, which directly acts on the soil, reducing heat loss to the air and other environments. Especially in low-temperature environments, it can quickly break the low temperature limit of soil and shorten the heating cycle of soil.

During installation, it can be buried to the required depth and density without disturbing the original soil structure. Suitable for various scenarios such as greenhouse planting, greenhouse seedling cultivation, permafrost thawing, soil pollution remediation (enhancing microbial activity), etc., unaffected by external weather conditions.

The system takes undisturbed soil, with a soil column area of 1 square meter and customizable height.

Original state soil sampling

The system can also be combined with SoilGAS CO2 CH4 N2O H2O online monitoring instrument and iChamber LY evapotranspiration canopy chamber to measure soil CO2, CH4, and N2O emission fluxes online and in real time. The monitoring instrument is based on the principle of laser absorption spectroscopy, with a measurement accuracy of ppb level.

SoilGAS CO2 CH4 N2O H2O Online Monitoring Instrument

The iChamber LY evapotranspiration canopy chamber is independently developed and designed by Ausnutria, with controllable lifting and lowering, no borders or columns, and no impact on microclimates such as rainfall and wind speed at measurement points. It can be used for measuring soil greenhouse gas flux and also as a community photosynthetic chamber.

The multi-channel control of the system configuration can carry up to 27 canopy chambers. The measurement time for each canopy chamber can be set.

IChamber LY evapotranspiration canopy chamber