Why in news?
A new study by researchers from the Environment Department of Himachal Pradesh University (HPU) in Shimla has identified the Sal tree as one of the most effective natural air purifiers. The scientists found that the tree’s thick, wax‑coated leaves and dense canopy can trap dust and neutralise harmful gases, making it particularly useful for combating urban air pollution.
Background
Shorea robusta, commonly known as the Sal tree, is a large deciduous tree belonging to the dipterocarp family. Native to the Indian subcontinent, it occurs in Uttarakhand’s terai region, the plains of Uttar Pradesh, Jharkhand, Odisha, Madhya Pradesh, Chhattisgarh and West Bengal, and extends into Nepal and Bangladesh. The tree can live for up to a century and is often called the “Sentinel of the Forests” because of its longevity and resilience. It grows 18–32 metres tall with a trunk diameter of 1.5–2 metres and has a spreading crown.
Climatic and ecological preferences
- Habitat: Sal grows in both dry and moist deciduous forests on well‑drained loamy soils. It thrives in tropical and sub‑tropical climates with monsoon rainfall.
- Altitude: The species occurs from sea level up to about 1,500 metres and forms extensive forests in the terai and central Indian highlands.
- Ecological role: Sal forests cover roughly 11 million hectares across India, Nepal and Bangladesh and provide habitat for numerous birds, mammals and insects. Its straight, durable wood is prized for construction, railway sleepers and furniture, while the leaves and resin have religious and medicinal uses.
