Spatiotemporal variability of photosynthetic and non-photosynthetic vegetation under climate change in arid and semiarid regions in China

Understanding the spatiotemporal characteristics of photosynthetic vegetation (PV) and non-photosynthetic vegetation (NPV) is critical for the study of vegetation in arid and semiarid regions. However, the evaluation of the fractional cover of PV (f (PV)) and NPV (f (NPV)) in Xinjiang has received very little attention. Thus, this study aims to evaluate the spatiotemporal variation characteristics of PV and NPV and their responses to precipitation and temperature in Xinjiang from 2001 to 2020. The results showed that the overall stability of f (PV) and f (NPV) were of the low fluctuation and high fluctuation types, respectively. A significant increase trend of f (PV) was found in most regions (P < 0.01), while f (NPV) showed an insignificant increase trend in general, except for eastern Xinjiang (P > 0.05). The comparison of f (PV) and f (NPV) shows that the vegetation of Xinjiang has improved over time, except for the Yili region, showing the need to strengthen the environmental protection of this region. Through the spatial analysis, some agricultural oasis areas experienced an expansion in the distribution of vegetation, while some sparse vegetation distribution area has not improved. From the climate perspective, the response degree of f (PV) and f (NPV) with precipitation is higher than that of temperature. The responses of f (PV) and f (NPV) to precipitation are greater in the summer and spring phases, respectively. Whereas, the responses of both f (PV) and f (NPV) to temperature are greater in the autumn phase. In the time phase, precipitation mainly promotes the distribution of PV and NPV, while temperature mainly inhibits their distribution. This study provides a theoretical basis for ecological restoration and conservation in Xinjiang and other arid and semiarid regions worldwide.