In a groundbreaking study published in Nature Cities, researchers have revealed that artificial light at night (ALAN) has a more significant impact on extending the growing seasons of urban vegetation than temperature.
This challenges long-held beliefs that primarily attribute shifts in plant life cycles to climate change-driven temperature changes. The implications of this research extend to our understanding of urban ecosystems, biodiversity, and global carbon cycles.
The study, using satellite data and ground observations, found that urban areas with high ALAN exposure showed prolonged growing seasons compared to less illuminated areas, even with similar climates.
ALAN disrupts plants' natural rhythms, causing them to perceive the artificial light as an extension of daylight. This can lead to continued photosynthetic activity, effectively lengthening the growing season.
This phenomenon is particularly noticeable in urban trees and ornamental plants. Extended photosynthetic periods can alter carbon assimilation and affect resource allocation, potentially influencing growth and susceptibility to pests.
Researchers are calling for more nuanced models that consider both environmental and human influences on urban ecosystems. They also highlight the need to reevaluate urban lighting policies, especially concerning the use of blue-rich white LEDs, which are particularly disruptive to vegetation.
The study also touches on broader ecological consequences, including potential changes in invasive species dynamics and disruptions to plant-pollinator interactions. The research emphasizes the need for interdisciplinary collaboration to address the ecological impact of ALAN and create sustainable urban futures.