# Artificial Light at Night Alters Photosynthetic Electron Transport in Two Deciduous Species

## TL;DR

Artificial light at night disrupts photosynthesis in two tree species, showing negative effects on their electron transport processes.

## Contribution

The study experimentally shows that low-intensity artificial light at night affects the photosynthetic electron transport in deciduous plants.

## Key findings

- Nighttime lighting disrupted electron transport in both common beech and white dogwood.
- Parameters like RE0/ET0, RE0/ABS, and PItotal were reduced under artificial light at night.
- The study provides a foundation for understanding long-term impacts of light pollution on plant physiology.

## Abstract

Light pollution is one of the fastest growing environmental issues of our time. While ubiquitous light was once thought to improve our functioning as a society, increasing safety and efficiency, it has turned out to be a major ecological problem. Artificial light at night disturbs the natural day–night cycle, and the lack of a dark phase interferes with the functioning of all living organisms. One of the first described observations in plants was visible changes in leaf development. Spring budburst and autumn leaf fall differ in plants located near artificial light sources compared to plants growing further from the light source or under natural night. These phenomena were described based on visual observations. The in-depth reactions and consequences of light pollution in plants are still not known. In the present study, we examined two woody plant species’ electron transport chain reactions after different night light doses. The results confirmed that light pollution, even in low intensity, can disrupt the functioning of the light phase of photosynthesis in plants. Both species revealed a disturbance in energy transformation. We do not know the impact of long exposure to this factor; however, it may lead to serious disturbances in plant functioning.

Although light pollution is one of the fastest-growing environmental problems today, we still know little about its impact on specific organisms. Plants are the least understood group in this context. Although environmental observations may suggest some conclusions, we still need more specific experimental data. The present study involved two deciduous species—common beech (Fagus sylvatica L.) and white dogwood (Cornus alba L.)—which, after being placed in growth room, were exposed to additional light at night. The effect of two different nighttime lighting combinations on leaf physiology was analyzed by measuring chlorophyll fluorescence. Nighttime lighting caused disruptions in electron transport, as evidenced by the reduced RE0/ET0, RE0/ABS, and PItotal parameters. This result confirms the negative impact of light pollution on plant functioning and provides a basis for further, more in-depth research.