## 1 Introduction  
Drought, a frequent global disaster with prolonged duration and extensive impacts, arises primarily from uneven precipitation distribution and imbalances between precipitation and evaporation [1]. Its extreme effects profoundly influence terrestrial ecosystems, with vegetation serving as a key indicator of environmental changes and a critical link in studying ecosystem-climate interactions. Recent studies emphasize vegetation's adaptive strategies (e.g., hydraulic regulation, phenological shifts) under drought stress, which are critical for predicting ecosystem stability under climate change [2, 3]. Drought is categorized into meteorological, agricultural, hydrological, and socioeconomic types, each affecting different systems [4]. Meteorological drought, caused by a prolonged precipitation-evaporation imbalance, can last months or years. Agricultural drought affects plant functionality due to water imbalance, while hydrological drought involves water bodies failing to meet demand. Socioeconomic drought impacts industrial, agricultural, and domestic activities, disrupting water supply and demand. These drought types are interrelated, with meteorological drought often preceding others [5]. Recent work highlights compound droughts (e.g., concurrent meteorological and agricultural droughts), which exacerbate vegetation vulnerability. For example, [PERSON] et al. [6] indicated that concurrent soil and atmospheric droughts amplify vegetation stress globally. Drought significantly impacts vegetation by reducing photosynthesis, altering coverage, and decreasing productivity, which, in turn, affects hydrological cycles, carbon balance, and ecosystem structure [7; 8; 9]. Vegetation's stability under drought is assessed by resistance and resilience [10]. Vegetation resistance measures a plant community's ability to maintain function during drought. Vegetation resilience determines how quickly vegetation recovers after drought ends [11]. Vegetation resistance is influenced by various adaptive mechanisms, such as deep-rooting systems in temperate oak forests (_Quercus_ spp.) and stomatal regulation to minimize water loss [12]. In contrast, resilience is shaped by drought legacy effects--repeated droughts can weaken recovery capacity, though grasslands generally rebound faster than forests due to their shorter life cycles and simpler structure [13]. Drought's impact varies by vegetation type, climate zone, timing, intensity, and duration [14]. For instance, arid-zone vegetation is more sensitive to short-term drought than humid-zone vegetation, while semi-arid and semi-humid vegetation shows greater resistance and adaptability [15]. Forests in temperate regions exhibit high resistance, whereas those in arid regions have higher resilience but inconsistent resistance patterns [16]. Grasslands recover quickly post-drought due to their simple structure and lower productivity [17]. Drought timing and duration also significantly affect vegetation, with growing season droughts being particularly impactful [18]. Most studies focus on single time scales (e.g., monthly or seasonal drought impacts), lacking long-term (20-year) spatiotemporal trend analysis of vegetation responses to drought across different time scales (short-term, medium-term, long-term, seasonal, and one-year-lagged effects), particularly continuous monitoring in ecologically sensitive semi-arid agro-pastoral transition zones. Furthermore, most studies assess either vegetation resistance (drought tolerance) or resilience (recovery capacity) separately, without integrating both to evaluate ecosystem stability under prolonged drought stress. To address these gaps, this study investigates vegetation responses to short-term (1 month), medium-term (6 months), long-term (one year), seasonal (spring, summer, autumn, and winter) and one-year-lagged drought in the ecologically vulnerable West Liao River Basin, specifically examining the resistance and resilience of vegetation under varying drought conditions.