Shuitu Baochi Xuebao (Dec 2024)
Response of Soil Respiration to Snowfall in a Kubuqi Salix Plantation Forest of During Freeze-thaw Period
Abstract
[Objective] To investigate the changes of soil respiration in desert ecosystems and its relationship with environmental factors during the spring freeze-thaw period in arid and semi-arid regions, and to provide data support for the carbon budget of sandy land ecosystems in arid and semi-arid regions. [Methods] Soil respiration rates of salix plantations that were untouched and unlevelled stubble (ww), untouched and levelled stubble (wp), untouched and unlevelled stubble (zw), and levelled and levelled stubble (zp) were measured in the snow-free treatment by using the Li-6800 soil-carbon-water flux measurement chamber in the Salix Forest Germplasm Resource Bank of the Dalate Banner, Ordos, Inner Mongolia, and the atmospheric temperature, soil temperature and humidity were measured simultaneously. [Results] The results showed that the daily change of soil respiration during the freeze-thaw alternation period showed a unimodal trend, with the peak occurring between 10:00 am and 12:00 pm. Snowfall accelerated soil respiration rate and enhanced the temperature sensitivity of soil respiration (Q10) during the spring freeze-thaw period, but it did not change the daily change pattern of soil respiration. After stubble levelling of the salix plantation, soil respiration rate slowed down but Q10 increased; land preparation measure reduced the daily flux of soil respiration in general, and it also reduced the Q10 value. Soil respiration was significantly correlated with soil temperature under each treatment, and the single factor model could explain 51%~68% of the variation in soil respiration (p<0.001), but the correlation between soil respiration and soil moisture was not significant. The two-factor composite model of soil temperature and moisture explained soil respiration better than the single factor model, and it explained 81% of the variation in soil respiration. The simulation results of the structural equation modelling (SEM) showed that all factors could jointly explain 70% of the variation in soil respiration rate, snowfall and stubble levelling directly affected soil respiration, and land preparation affected soil respiration indirectly by affecting soil temperature and moisture. [Conclusion] Snowfall in winter can provide water for vegetation growth in early spring, and it regulates the carbon budget in arid and semi-arid regions; stubble levelling and land preparation can impede the release of carbon during the freeze-thaw period in arid and semi-arid areas and indirectly slow down the loss of carbon from the soil, thus contributing to the regulation of the carbon budget of the ecosystem.
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