Urban Lighting and Heat Shaping Plant Growth in Cities
Urban Flora Sprouts and Blooms Prematurely and Longer Periods
Cities, with their endless sources of artificial light and higher temperatures, are reshaping the life cycles of plants around them. A study published in the journal "Nature Cities" reveals that this phenomenon results in spring starting sooner and autumn lasting longer than in rural areas.
Quick Fact: Cities with the most significant difference in the onset of growth between urban and rural areas are mainly found in Southeast Asia, Europe, and North America's northwest coast.
The Infamous Urban Light Pollution
From street lamps to illuminated billboards, cities continuously bathe in artificial light, even at night. This persistent illumination affects plant growth in ways researchers are beginning to understand. Artificial urban lighting, on average, delays the natural end of the growing period in plants by around eleven days in autumn. Moreover, it causes the growing period to start about 12.5 days earlier than in rural areas in combination with higher urban temperatures.
A Combined Attack on Plant Phenology
The research team, led by Lin Meng of Vanderbilt University in Nashville, USA, sought to uncover the specific roles that artificial light and higher heat radiation from concrete, stones, and other urban materials play in flowering, growth, and the timing of when plants shed their leaves. They discovered that both artificial light and temperature contribute almost equally in spring to urban plants sprouting earlier than their rural counterparts. However, during autumn, it is almost exclusively artificial light that extends the growing season by delaying leaf coloring and shedding.
Some exceptions exist, though, such as in European cities with higher temperatures. In these cases, the team noticed a shorter growing season, which they attribute to water scarcity. Higher summer and autumn temperatures can lead to longer growth periods, but they can also deplete water resources, causing premature leaf aging and accelerating developments in autumn.
A New Twist: The Influence of LED Lighting
Traditional lamps like sodium vapor lamps have been slowly phased out in favor of energy-saving LEDs. This change might have profound implications for plant development, as the study suggests. The spoken question concerns the impact of LED lighting, with its strong blue light emissions, on plant development. This area remains largely unexplored.
- Urban Heat Island Effect
- Artificial Light
- Plant Phenology
Sources: ntv.de, Stefan Parsch, dpa
Behind the Scenes:
- Artificial Light's Impact on Plants: Artificial light at night (ALAN) can override natural temperature-driven cues, leading to earlier leaf-out and delayed senescence compared to rural areas. This extended rural-urban difference may contribute to the urban heat island effect.
- Urban Heat Island Effect: This phenomenon occurs in cities due to factors like heat-absorbing materials (asphalt, concrete), limited green spaces, increased energy use, and urban geometry, resulting in higher urban temperatures.
- Plant Phenology: Refers to the timing of life cycle events like leaf-out and senescence in plants, which is primarily influenced by temperature but can also be affected by artificial light and urban temperatures. The urban heat island effect can contribute to earlier springs and later autumns.
- Synergistic Effect: The combination of artificial light and higher urban temperatures synergistically affects plant growth periods, creating a more favorable environment for extended plant productivity in cities but potentially impacting long-term plant health and biodiversity.
- Environmental science reveals that urban climate change, influenced by the urban heat island effect and persistent artificial light, significantly impacts plant phenology, causing earlier springs and longer autumns compared to rural areas.
- In the realm of health-and-wellness and fitness-and-exercise, understanding the science behind urban plant growth is essential as it could help city planners create more sustainable environments, thereby promoting overall well-being and reducing the impacts of climate change.
- Investigations into environmental science, specifically the effects of climate change and the synergistic impact of artificial light and higher urban temperatures, have shown that these factors contribute to a shift in plant life cycles, which may have broader implications for the ecosystem and biodiversity within cities.
