###### Abstract  
Forest phenology directly reacts to global climate change, potentially regulating greenhouse gas fluxes between ecosystems and the atmosphere. To explore this phenomenon in two plain poplar (_Populus_ spp.) forests in eastern China, we measured CO\({}_{2}\) fluxes and phenology at the canopy scale based on the eddy covariance and PhenoCam technology. From 2019 to 2022, poplars in a high-speed wind site (HWS) experienced shorter maturity durations (108 \(\pm\) 4.9 days vs. 152 \(\pm\) 1.2 days) and an earlier date of foliar senescence (day of year: 223.8 \(\pm\) 2.5 vs. 259.5 \(\pm\) 0.9) than those in the low-speed wind site (LWS). The annual net CO\({}_{2}\) uptake in the HWS (689.65 \(\pm\) 105.15 g C\(\cdot\)m\({}^{-2}\cdot\)year\({}^{-1}\)) was approximately 2.4 times higher than that in the LWS (285.65 \(\pm\) 81.37 g C\(\cdot\)m\({}^{-2}\cdot\)year\({}^{-1}\)). Our results indicate that environmental changes like wind stress alter forest phenology that can dynamically regulate ecosystem respiration and gross primary production.  
wind; carbon uptake; eddy covariance; PhenoCam 2022 15 2240  
peak greenness trends globally [19]. Therefore, when assessing the effect of phenology on carbon sequestration efficiency in forest ecosystems, conducting a comprehensive analysis is important. Such analysis should consider the influence of environmental factors (such as temperature and water stress) on photosynthesis and respiration.  
The relationship between forest phenology and carbon dynamics has been extensively studied and reported in the peer-reviewed literature, with standardized procedures used to identify important phenological phases, including green-up, maturity, senescence, and dormancy [20; 21; 22]. Analyzing digital images in conjunction with carbon-flux measurements at the ecosystem level can provide insights into these phases and enable the modeling of ecosystem productivity [23]. In most studies focusing on phenology and carbon fluxes, warming has been acknowledged as a primary influencing factor [18; 24; 25]. However, a few studies have focused on the interrelationship between forest phenology and wind, although wind strength significantly alters forest phenology by regulating the hydrological cycle [26]. The direct effects of the wind strength on the phenology of the same species and its subsequent role in regulating CO\({}_{2}\) are not well defined. It is therefore important to answer these questions from a phenological perspective.  
Poplar is an efficient choice for timber forests and protected forests in China because of its short maturation period and adaptability to various climate conditions. The objectives of this study were to (1) compare the CO\({}_{2}\) fluxes between two sites with different soil textures and wind speeds in eastern China and (2) determine how changes in plant phenology alter CO\({}_{2}\) fluxes in two poplar forests, identifying the predominant biophysical factors that control fluxes across phenological phases in such forests. We used the eddy covariance technique to measure CO\({}_{2}\) exchange between the forests and the atmosphere. We then captured phenological changes in the forests using a digital camera. Additionally, we tested the hypothesis that stronger winds would dominate variations in leaf conditions and therefore regulate net ecosystem exchange (NEE) by controlling ecosystem respiration (RE).