Context:

A recent study reveals that High levels of artificial light at night (ALAN) make tree leaves tougher and harder for insects to eat.

Key findings of the study

• The Chinese Academy of Sciences found that ALAN can enhance leaf toughness while concurrently reducing leaf herbivory (feeding on living plant parts by insects and animals) levels.
• The study, published in the journal Frontiers in Plant Science, highlighted that ALAN has species-specific effects on leaf nutrients, size, and defence substances.
• Plants experiencing high levels of artificial light focus on defence rather than growth, producing tougher leaves with more chemical defence compounds.
• The study observed this phenomenon in two common street tree species in Beijing:
  Japanese pagoda tree (Styphnolobium japonicum).
  Green ash (Fraxinus pennsylvanica).
• In Styphnolobium japonicum, herbivory decreases with higher leaf carbon content and toughness but increases with more leaf nitrogen. Higher specific leaf areas (SLA) and ALAN also reduce herbivory. 
• In Fraxinus pennsylvanica, tougher leaves lead to less herbivory.
• The interaction between SLA and ALAN showed a significant negative effect on herbivory. The higher the SLA and ALAN, the lower the herbivory. 
• Higher leaf toughness implies intensified mechanical defence, hindering herbivore feeding and resulting in lower herbivory levels. 
• Leaves with higher toughness also decompose at a slower rate, potentially affecting nutrient cycling negatively.
• High ALAN intensity is detrimental to the energy flow from plants to higher trophic levels.
• The 2016 report New World Atlas of Artificial Night Sky Brightness, published in Science Advances, found that more than 80 percent of the world's population lives under light-polluted skies.
• On January 11, 2024, Pench Tiger Reserve in Maharashtra became India's first International Dark Sky Park, certified by the International Dark-Sky Association. This is the fifth such park in Asia, focused on preserving the night sky and promoting astronomy.

What is light Pollution? 

• It is defined as the presence of unwanted, inappropriate, or excessive artificial lighting, which can have numerous negative impacts.
• It impacts animal behaviours, such as migration patterns, wake-sleep habits, and habitat formation.