About Sal Tree
 
Required Climatic Conditions for Sal Tree
 
Key Climatic Conditions
 

Condition	Range/Description
Climate Type	Tropical Moist Deciduous and Tropical Dry Deciduous forests
Temperature	Maximum: 36°C to 44°C; Minimum: 11°C to 17°C
Annual Rainfall	1,000 mm to 3,500 mm (tolerates up to 7,300 mm in some cases)
Dry Season	A defined dry season of 4 to 8 months is typical. It cannot grow in locations with more than 7 consecutive dry months (less than 50 mm rainfall per month).
Light	Sal is a light-demanding species and requires full overhead light for optimal growth, though young seedlings need some protection from frost and intense drought.
Altitude	Found from near sea level up to elevations of over 1,500 meters.

Soil Requirements
 
Response to Moisture

• In wetter areas, the Sal tree tends to be evergreen.
• In drier areas, it is dry-season deciduous, shedding most of its leaves from February to April, before leafing out again in April and May. This leaf exchange is a survival strategy to reduce water loss during the dry season.
• Soil moisture, particularly during the seedling stage, is crucial for successful regeneration and establishment. 

Key Characteristics

• Botanical Name: Shorea robusta
• Appearance: Sal trees are tall, reaching up to 30-40 meters (about 100-130 feet), with a straight, cylindrical trunk and a rounded crown in older trees. The bark is dark brown and develops deep longitudinal fissures with age.
• Leaves: The leaves are large (10-25 cm long), leathery, and shiny, with a distinct oval shape and a pointy tip.
• Flowers and Fruit: It produces small, yellowish-white flowers in terminal or axillary panicles during the spring (March-April). The fruit is an ovoid nut with five prominent, wing-like calyx lobes that help in wind dispersal in June-July.
• Habitat: It is found in moist deciduous forests, primarily in the lower Himalayan foothills, and across northern and central India (including Jharkhand, Chhattisgarh, Odisha, Assam, Uttar Pradesh, and Madhya Pradesh), as well as in Nepal and Bangladesh. In wetter areas, it is nearly evergreen, but in drier conditions, it sheds most of its leaves in the dry season (February-April). 

Uses and Significance

• Timber: Sal wood is one of the most important sources of hardwood timber in India, second only to teak. It is coarse-grained, light-colored when cut but darkens on exposure, and highly prized for its durability and resistance to termites and water, making it ideal for construction, railway sleepers, door and window frames, and boat building.
• Medicinal Uses: Various parts of the tree (bark, resin, leaves, and seeds) are used in Ayurvedic and traditional medicine. The resin is used as an astringent and detergent in treatments for diarrhea, dysentery, and skin ailments. Its oil is used in ointments for skin diseases and joint pain.
• Economic Products: The leaves are traditionally used by local communities to make eco-friendly disposable plates and bowls (patravali and dona). The seeds yield an edible oil known as Sal butter, used for cooking and lighting lamps, while the resin (Sal dammar) is burned as incense.
• Cultural and Religious Importance: The Sal tree holds immense spiritual value.
  • Buddhism: Queen Maya is believed to have given birth to Gautam Buddha while holding onto a Sal tree branch, and Buddha is said to have passed away (attained Parinibbana) between twin Sal trees.
  • Jainism: It is believed the 24th Tirthankara, Mahavira, achieved enlightenment under a Sal tree.
  • Hinduism and Tribal Culture: In Hindu tradition, the tree is associated with Lord Vishnu. Many tribal communities in India, such as the Munda and Santhal, worship the Sal tree as a goddess (Sarna Burhi) and celebrate festivals, such as Sarhul, that revolve around its flowering. 

How can Sal Trees Control Pollution?

• Interception of Particulate Matter: Sal trees have large leaves and dense canopies that physically intercept airborne particulate matter (PM), such as dust, smoke, and soot. These particles are deposited on the leaf surfaces, branches, and bark, and are then washed to the ground by rain, where they enter the soil or are dissolved in storm water runoff.
• Absorption of Gaseous Pollutants: Through the process of photosynthesis, trees absorb carbon dioxide (CO2) through tiny pores on their leaves called stomata. Sal trees have a high biomass and are effective carbon sinks, sequestering significant amounts of CO2 over their long lifespan. They also absorb other gaseous pollutants like carbon monoxide (CO), sulfur dioxide (SO2), and ground-level ozone.
• Temperature Reduction: Sal trees provide extensive shade and release water vapor through transpiration, which cools the surrounding air. Lower ambient temperatures indirectly reduce the formation of certain air pollutants, particularly ground-level ozone, which forms more readily in heat.
• Soil and Water Remediation (Phytoremediation): The root systems of Sal trees help to clean and filter rainwater and absorb unwanted chemicals and heavy metals from the surrounding soil and groundwater, preventing these contaminants from entering waterways.

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