Can wind farms change the phenology of grassland in China?

Wind energy has attracted worldwide attention as a clean energy source and wind farms are rapidly increasing in number. However, operation of wind farms can affect the local climate and, consequently, local vegetation phenology. Hence, the influence of wind farms on phenology needs to be understood. In this paper, we use remote sensing MOD09GQ data to calculate phenological indexes of vegetation near a large wind farm in a semi-arid grassland area of Inner Mongolia, China. The vegetation phenology before and wind farm construction is compared, with a control area used to account for long-term climate change. The results show that the wind farm extended the growing season of vegetation in areas upwind and downwind of the wind farm. In the prevailing wind direction, the growing season was extended by 11.7 days within 4 km of the wind farm in the upwind area, by 10.0 days within the wind farm, and by 5.5 days within 4 km of the wind farm in the downwind area. The extension of the growing season is due to an earlier start of the growing season, which was mainly influenced by increases in local land surface temperatures. And such an extension will increase the evaporation from vegetation transpiration in study area, which is very likely to bring about decreases in soil moisture here. Such effects should be considered when assessing the ecological impacts of planned wind farms.