Changes in the amount of photosynthetic pigments in the native Artemisia diffusa in the semi-desert rangelands of Uzbekistan under the influence of different sheep grazing intensities and different seasons

Rangelands, as critical components of terrestrial ecosystems, play a pivotal role in supporting biodiversity and providing essential ecosystem services. The relationship between grazing activities and vegetation dynamics is a topic of ongoing research, with a focus on understanding how these interactions influence key physiological processes in dominant plant species. This study investigated the changes in photosynthetic pigments of rangeland Artemisia diffusa under varying sheep grazing intensities. Four different grazing intensities were imposed: initial, low, medium, and high. Sampling took place at regular intervals over the 2021-2022 year spring sezon to assess the temporal dynamics of photosynthetic pigments. The study focused on measuring changes in the concentration of key photosynthetic pigments, including chlorophyll-a, chlorophyll-b, and carotenoids, in selected Artemisia diffusa species over the grazing period. Our results showed a clear correlation between sheep grazing intensity and changes in photosynthetic pigment concentration. In general, Artemisia diffusa at initial and low intensities showed lower levels of chlorophyll a and b than those at moderate and high intensities. Carotenoid concentrations were also observed to change significantly and increase significantly at high sheep grazing intensities.