Effects of biocrusts on water evapotranspiration of shrub-grass ecosystem in water-wind erosion crisscross region of Loess Plateau
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1.College of Natural Resources and Environment, Northwest A&2.F University;3.State Key Laboratory of Soil Erosion and Dryland Agriculture on the Loess Plateau, Research Center for Soil and Water Conservation and Eco-Environment, Ministry of Education, Chinese Academy of Sciences

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    Abstract:

    Evapotranspiration is the main way of soil water loss. However, as a widely distributed surface cover in arid and semi-arid regions, how biocrusts (biological soil crusts) affect ecosystem evapotranspiration was still not clear to date. Thus, we investigated the effect of biocrusts on evapotranspiration of shrub-grass ecosystem in water-wind erosion crisscross region of Loess Plateau by using soil columns in the study. The bare soil column was used as control, and three treatments were set up, they were shrub-grass (single plant shrub-20% grass), shrub-grass-30% biocrust and shrub-grass-50% biocrust. The results showed that after 12 hours of simulated 30 mm precipitation infiltration, the water content of 0 ~ 20 cm soil layer in the shrub-grass-biotic crust treatment was 15.4 % higher than that in the bare soil treatment and 12.8 % higher than that in the shrub-grass treatment. Compared with bare soil, shrub-grass and shrub-grass with different coverage biocrusts significantly increased soil water dissipation. Among them, shrub-grass treatment increased by 120.3 % compared with bare soil, and shrub-grass-biocrust increased by 116.5 % on average compared with bare soil. The biological crust reduced the water dissipation of the shrub-grass ecosystem. Compared with the shrub-grass treatment, the water dissipation of the shrub-grass-biological crust decreased by 1.7 % on average, and the degree of reduction was related to the coverage, time period and soil depth of the biological crust. Among them, the water dissipation of shrub-grass-30 % biological crust and shrub-grass-50 % biological crust treatments increased by 5.3 % and decreased by 8.7 %, respectively, compared with shrub-grass treatment. The effect of biological crusts on the reduction of water dissipation in shrub-herb ecosystem was obvious in 1-4 days after rain. Biological crusts mainly reduce evapotranspiration and evapotranspiration rate by reducing water dissipation in the soil layer below 20 cm of shrub-grass ecosystem. Compared with the shrub-grass treatment, the evapotranspiration loss of 0-20 cm soil layer in the shrub-grass-biotic crust treatment increased by 14.4 %, and the water dissipation in the soil layer below 20 cm decreased by 15.5 %. This paper further improves the study of the effect of biological crusts on soil moisture and provides a scientific basis for improving the accuracy of evapotranspiration model prediction.

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History
  • Received:February 25,2024
  • Revised:March 29,2024
  • Adopted:April 15,2024
  • Online: April 30,2024
  • Published: