In recent decades, the escalating impact of global warming has manifested in a variety of profound alterations to Earth’s ecosystems. Among the most pervasive of these changes is the increased frequency and severity of drought events, which impose heavy constraints on terrestrial vegetation dynamics. While drought-induced shifts in plant physiology and growth during the drought period itself have been extensively characterized, emerging research now reveals that the repercussions of drought extend far beyond the immediate event. Specifically, these climatic stressors are leaving legacies that significantly disrupt phenological events such as spring green-up and leaf unfolding in the subsequent growing season.
A groundbreaking study led by Liu, Zhang, Peñuelas, and colleagues, published in Nature Climate Change in 2025, delves into these drought legacies and their profound influence on northern ecosystems. By synthesizing long-term in situ observations with high-resolution satellite-derived greenness indices, the researchers unveil a consistent and robust delay in spring phenology following severe drought episodes. This delay, which spans the critical phases of green-up and leaf emergence, may critically undermine plant productivity and ecosystem carbon sequestration, challenging existing projections of climate-driven phenological advances.
The research underscores how traditional phenology models, which typically integrate temperature and light cues as primary drivers, fall short in capturing these drought aftermath effects. Unlike the immediate drought responses that are relatively well understood, the mechanisms behind postdrought phenological delays appear to be multifaceted, involving intricate feedbacks between environmental conditions and plant physiological status. Notably, the study identifies soil moisture recovery timing and the duration of preceding drought events as pivotal determinants of the magnitude of phenological delay.
Intriguingly, the authors distinguish between endogenous memory effects — changes stored within the plants themselves, such as altered carbohydrate reserves or hormone levels — and exogenous memory effects, which are imposed externally through modifications of the local environment after drought cessation. Evidence from diverse dryland and non-dryland biomes reveals that exogenous influences, including lingering soil moisture deficits and altered microclimatic conditions, eclipse endogenous effects by factors of five and two, respectively. This differentiation underscores the critical role of the postdrought environment in shaping plant recovery trajectories.
A key environmental vector modulating these legacy impacts is postdrought temperature. While warming trends generally accelerate phenology under normal circumstances, elevated temperatures following drought can exacerbate moisture stress or disrupt photosynthetic recovery, thereby prolonging the delay in green-up. Such counterintuitive temperature-phenology interactions emphasize the complexity of plant-environment feedbacks under the dual pressures of warming and hydric stress.
The dataset analyzed spans multiple northern ecosystem types, capturing variability in climate regimes and vegetation composition. Using advanced satellite greenness metrics like NDVI and EVI, combined with fine-grained soil moisture measurements, the study provides unparalleled temporal and spatial resolution for assessing drought legacies. These cutting-edge remote sensing techniques allow quantification of subtle phenological shifts that might otherwise evade traditional ground observations.
From an ecological perspective, delayed spring phenology following drought events has cascading consequences. Extended dormancy shortens the growing season, reducing carbon uptake and biomass accumulation. This, in turn, may impair ecosystem resilience and productivity, influencing trophic interactions and overall biodiversity. Moreover, the altered timing of leaf-out potentially mismatches plant phenology with pollinator activity and herbivore life cycles, disrupting established ecological synchronies.
The findings challenge prevailing assumptions that warming alone will result in earlier spring green-up globally. Instead, the interplay between increased drought incidence and temperature dynamics may mitigate or even reverse anticipated phenological advances. This nuanced insight underscores the need for updated ecosystem models incorporating legacy effects to improve predictions of plant community responses under future climate scenarios.
Physiological analyses presented in the study highlight drought-induced reductions in photosynthetic capacity as a key biological mechanism driving delayed phenology. Prolonged water deficits impair chlorophyll synthesis and stomatal conductance, hampering carbon assimilation even after drought relief. The impaired recovery constrains energy availability necessary for initiating leaf expansion and unfolding, consistent with observed delays.
By dissecting drought legacies into their constituent components, the research opens new avenues for targeted ecosystem management. Restoration efforts and adaptive strategies might focus on enhancing soil moisture retention and microclimate buffering post-drought, aiming to shorten phenological lags. Furthermore, understanding regional variability in drought memory effects can inform climate-resilient forest and grassland stewardship.
The temporal persistence of drought legacies observed spans multiple seasons, indicating that these effects are not transient but hold potential to compound with successive dry periods. Such cumulative impacts could irreversibly alter ecosystem structure and function, with significant implications for carbon cycling and climate feedbacks. This highlights the urgency of integrating legacy considerations into long-term ecological monitoring frameworks.
In sum, this pioneering work significantly enriches our understanding of how drought stresses extend beyond their immediate occurrence to shape the phenological future of northern ecosystems. It also exemplifies the power of combining remote sensing with ground-based measurements to unravel complex climate-vegetation interactions across scales. As drought frequency and severity continue to rise under ongoing global warming trends, recognizing and accounting for these legacy effects will be vital for accurate forecasts and effective environmental management.
The study challenges researchers and policymakers alike to rethink the potential of spring phenological shifts as straightforward indicators of warming. Instead, it posits a more intricate scenario where drought legacies moderate, delay, and sometimes counteract temperature-driven phenological change. This refined perspective advocates for integrated approaches encompassing hydrological, physiological, and climatological factors to better anticipate the future trajectory of terrestrial ecosystems in a rapidly changing climate.
As forests and grasslands navigate this hydrological uncertainty, the insights from Liu et al.’s research prompt urgent reconsideration of how resilience is defined and fostered in ecological systems. Addressing the compounding stresses of drought legacy and warming will require interdisciplinary collaborations bridging ecology, remote sensing, plant physiology, and climate science.
Ultimately, the suppression of expected spring phenological advances due to persistent drought legacies constitutes a critical feedback mechanism. It may lead to reduced carbon uptake during peak growing seasons, thus diminishing the biosphere’s capacity to offset anthropogenic CO2 emissions. Incorporating these findings into climate feedback models is essential to forecast more realistic outcomes of future climate-ecosystem interactions.
This study marks a significant advancement in drought ecology, revealing that the aftershocks of water scarcity events resonate through seasons to influence vegetation dynamics in unforeseen ways. The implications for ecosystem productivity, biodiversity maintenance, and carbon balance underscore the necessity for ongoing, high-resolution monitoring combined with mechanistic modeling to navigate an uncertain climatic future.
Subject of Research: Effects of drought legacies on spring phenology and ecosystem functioning in northern terrestrial ecosystems
Article Title: Drought legacies delay spring green-up in northern ecosystems
Article References:
Liu, Y., Zhang, Y., Peñuelas, J. et al. Drought legacies delay spring green-up in northern ecosystems. Nat. Clim. Chang. 15, 444–451 (2025). https://doi.org/10.1038/s41558-025-02273-6
Image Credits: AI Generated
