Too much light for plants protects them from insects?

This post I stumbled upon from The Guardian. The key to the post was a research paper in Frontiers in Plant Science. Here’s the Guardian’s summary that should get everybody’s attention.

Streetlights left on all night cause leaves to become so tough that insects cannot eat them, threatening the food chain, a study has found.

The Guardian

So if insects cannot eat the plants toughened by too much artificial light, then the entire food chain in those areas (whose foundation = insects)is at risk. Here is the summary from the researchers.

Artificial light at night (ALAN) is exerting growing pressure on natural ecosystems, but its impact on biological interactions remains unclear. This study aimed to assess how ALAN influences leaf functional traits and herbivory in two prevalent street tree species (Styphnolobium japonicum (L.) Schott and Fraxinus pennsylvanica) through field surveys and paired experiments in the urban areas of Beijing, China. We found that ALAN led to increased leaf toughness and decreased levels of leaf herbivory. Additionally, ALAN showed species-specific effects on leaf nutrients, size as well as defense substances. The findings illustrate that ALAN can significantly alter some key functional traits and ecological processes (nutrient cycling, energy flow). In general, we suggest that high ALAN intensity will be detrimental to the energy flow from urban plants to higher trophic levels, posing a potential threat to the maintenance of biodiversity (e.g., arthropod diversity, bird diversity) in urban ecosystems.

Frontiers in Plant Science

The unintended consequences of natural light that are just now being understood? How much artificial light is required for such a change is unknown, but the researchers start with this dataset.

More than 80% of the world’s population lives with daily light pollution, experiencing at least an 8% increase in nighttime brightness compared to natural levels (Gaston et al., 2015; Falchi et al., 2016). Recognized as a major concern in global change for the 21st century, artificial light at night (ALAN) possesses widespread, distinctive, and rapidly growing pollution characteristics that have the potential to alter natural ecosystems (Svechkina et al., 2020; Sanders et al., 2021), particularly in urban areas (Hopkins et al., 2018). The ecological effects of ALAN are increasingly acknowledged in urban ecosystems, particularly on the two sides of streets (Bennie et al., 2016; La Sorte et al., 2017). There are studies indicating that the intensity of ALAN has exceeded the threshold of plant adaptation, leading to changes in their physiological responses (Singhal et al., 2019; Jägerbrand and Spoelstra, 2023). While the ecological impacts of ALAN on urban plants have been observed for a long time, quantifying such effects empirically has been rare (Bennie et al., 2018). To date, relatively little research has been conducted on the effects of ALAN on key ecological processes such as herbivory, which hampers a comprehensive understanding of the impact of ALAN on urban ecosystems (Garrett et al., 2020).

Frontiers in Plant Science

While most of us could get excited about fewer insects and healthier plants in our urban areas, but then what would the birds eat?

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