Spatio-temporal Evolution of Vegetation and Its Climatic Driving Factors in the Kezhou, Northwest China

Abstract This study investigates the spatio-temporal evolution of vegetation ecosystems and climate-NPP relationships in Kezhou, Northwest China, from 2000 to 2020. Using preprocessed MOD13Q1 data, we analyzed NDVI, FVC, and NPP trends. Theil-Sen Median trend analysis combined with Mann-Kendall test was employed to examine NPP variation, while Pearson correlation analysis was applied pixel-by-pixel to explore temperature-precipitation-NPP relationships. Results show: (1) NDVI increased at a rate of 0.0021/year, with the mean value in 2011–2020 (0.141) exceeding that of 2000–2010 (0.125), displaying a "high northwest, low southeast" spatial pattern; (2) medium FVC (0.3–0.5) expanded significantly from 10.9% to 17.93%, although medium-low coverage still dominated at 91% in 2020; (3) NPP fluctuated upward initially, rising from 42 g C/m² (2000) to a peak of 51 g C/m² (2015), then declined sharply to 3.8 g C/m² in 2016–2017 (–25.5%) and maintained low levels thereafter, with spatial distribution showing "high north, low south" and 88% of the area exhibiting insignificant trends; (4) precipitation showed positive correlation with NPP across 50.3% of the area, exceeding temperature (43.7%), with central arid basins demonstrating "precipitation-positive, temperature-negative" patterns while the southwestern plateau exhibited warm-humid synergy. These findings indicate that while vegetation coverage achieved continuous improvement, post-2015 NPP dynamics reveal critical insights for sustainable ecosystem management: water availability emerges as the dominant controlling factor for productivity, and the identified climate-vegetation relationships provide a scientific foundation for adaptive strategies to address warming-drying challenges in central basins, thereby supporting targeted ecological restoration and enhanced climate resilience in arid regions. This research contributes to SDG 13 (Climate Action) and SDG 15 (Life on Land) by offering practical guidance for ecosystem restoration and sustainable land management in Belt and Road node areas.