Conclusions
In this study, we assessed the impact of different levels of grazing
intensity, as well as the associated direct and indirect effects, on
ecosystem carbon exchange and soil respiration. Over the course of the
growing season, we found that the desert steppe remained in a state of
carbon uptake (carbon sink) under the conditions of 16 years of
continuous grazing. Our study shows that alter patterns of net ecosystem
exchange primarily via their negative influence on the biomass of shrubs
and semi-shrubs. In addition, grazing-induced reduction belowground
biomass, as well as in total plant nitrogen and soil ammonium nitrogen,
can strongly influence ecosystem carbon exchange and soil respiration.
When nitrogen is lost from the soil due to grazing, plants reallocate
resources belowground to maintain growth and development, thus promoting
photosynthesis and respiration.