Light pollution is a growing concern for our planet, with an estimated 25% of the world already affected. As urban areas continue to expand, this problem is only getting worse, with an annual increase of around 6%. Over the past 25 years, global light pollution has increased by at least 49%, indicating a significant and concerning trend. This issue has implications for both human health and the natural world.
Light pollution is known to affect how plants grow and reproduce, as it can disrupt their seasonal rhythms and reproductive cycles. It has also been found that light pollution from streetlights can disrupt the flight patterns of moths and impede their pollination abilities. Over 70% of the observed moths were drawn towards lights and away from plants, resulting in reduced plant pollination and pollen transportation.
This can have a ripple effect on ecosystems as several pollinators are affected, including bees. The strained relationship between plants and pollinators due to light pollution can put our food supply in jeopardy. One broken link in the food chain can lead to unfathomable physiological consequences throughout the ecosystem.
But this was just the tip of the iceberg, lets dive deep into this issue.
Related: How does climate change impact our health?
Stressed Plants: The Negative Impact of Artificial Light and Climate Change
Artificial light at night disrupts the natural sleep-wake cycle, or circadian rhythm, of most living things on the planet. This can put undue stress on internal systems and lead to detrimental impacts. The longer the disruption goes on, the greater the potential for harm.
According to Joanne Chory, a professor at the Salk Institute for Biological Studies in San Diego, California, plants, like animals, need a sleep cycle to process and prioritize different activities throughout the day. This requires them to know the time of day and underscores the importance of maintaining a natural circadian rhythm.
Plants have photoreceptors that help them determine day length, which is crucial for events such as blooming and leaf shedding. There are currently 13 known photoreceptors, five of which absorb near-infrared light from the Moon and starlight, and eight that absorb a type of UV light. Light pollution can artificially extend the length of the day, causing these photoreceptors to trigger and potentially alter a plant’s flowering pattern.
According to Brett Seymoure, an ecologist and assistant professor of biological sciences at the University of Texas at El Paso, plants can become stressed and overwhelmed under artificial light. This is because they can photosynthesize more, leading to increased energy intake and potentially harmful levels of reactive oxygen that can damage or kill the plant. Additionally, warmer winters and longer summers due to climate change can cause trees to grow out of their natural rhythm, weakening them over time.
Impact of light pollution on trees’ energy levels and health
The timing of blooming or budbursts for plants is typically triggered by the arrival of warmer temperatures, longer days, and increased exposure to UV rays in the spring. However, artificial light at night is disrupting these natural cues, according to Seymoure.
The photoperiod, or the ratio of daytime to night time, is being masked by light pollution, causing plants to budburst sooner or hold onto their leaves longer than they typically would. Light pollution can also affect when trees budburst and when they shed their leaves in autumn. One study found that areas with more artificial light at night had budburst happen up to 7.5 days earlier.
The production of chlorophyll, which is essential to photosynthesis and the changing of leaf colours, can also be disrupted by light pollution, leading to trees holding on to their leaves for longer periods. This can have detrimental effects on the trees’ energy levels and overall health.
The Uncertain Future of Plant-Pollinator Relationship
Artificial light at night disrupts pollinators’ circadian rhythms and life patterns, hindering plant reproduction. Studies have found that nocturnal pollination is reduced under artificial lights, leading to lower plant-pollinator interactions and less pollen for diurnal pollinators like bees.
Light pollution also causes stress on pollinators’ bodies, reducing their sleep and recovery time, and making it harder for them to pollinate and reproduce. Additionally, light pollution can affect migration by disorienting birds’ migration routes and changing where they breed or overwinter, potentially impacting plants that depend on birds for pollination or seed dispersal.
Temperature and light changes play a critical role in the life processes of plants and pollinators, and as the planet experiences warming temperatures and increasing light pollution, these processes are being disrupted more and more. The ability of affected species to adapt quickly enough to survive these changes remains uncertain, and the consequences of their decline could be far-reaching for the delicate balance of life on this planet.
Ecologists are worried about the decline in pollinator populations, which could be caused by several stressors such as light pollution, habitat loss, chemical pollution, and climate change. Insects are essential to maintaining the balance of life on the planet, and their decline could have a severe domino effect.
For instance, if honeybees native to the US go extinct, all the plant species they pollinate could follow, which amounts to 80% of flowering plants. These plants are responsible for 25% of the food consumed by Americans today, according to the US Department of Agriculture.
Plants and insects have co-evolved over the past 200 million years, and any alteration in the behaviour or physiology of one affects the other. Light pollution creates a unique and unusual situation with consequences that could impact everything on the planet, given that almost everything depends on flowering plants and insects, with 80% of crop species pollinated by insects, says Seymoure.
Conclusion
Light pollution is having a profound impact on the natural world, disrupting the delicate balance between plants and pollinators. The effects of artificial light at night are far-reaching and complex, from altering the timing of flowering to disrupting pollinators’ circadian rhythms and migration patterns. The decline in pollinator populations due to stressors like light pollution, habitat loss, chemical pollution, and climate change is of great concern, given their vital role in maintaining the balance of life on the planet.
As we continue to warm the planet and increase light pollution, it remains uncertain if the affected species will adapt fast enough to survive these changes. It is crucial to address the issue of light pollution to help preserve the natural world’s delicate balance and ensure a sustainable future for all.
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