By Riaz Sohail
BBC Urdu service, Thatta
The trees were planted in a swampy mangrove region
A team of volunteers in Pakistan has set a new world record by planting more than half a million trees in one day.
Guinness World Records confirmed that 541,176 trees had been planted in the southern province of Sindh on 15 July.
Some 300 volunteers, working in groups, planted mangrove saplings in the 750 acres of the Indus river delta region.
They beat the previous team record for tree planting which was set in India just last month when 447,874 saplings were planted in Assam state.
Pakistan's tree-planting marathon was witnessed by representatives of Guinness World Records and the International Union for the Conservation of Nature.
Each group was issued saplings by a panel of experts which also monitored the planting process to ensure that standards set by Guinness World Records were met.
Aadil Ahmed, the Guinness representative, told the BBC he was there to ensure that no old plants were included in the count.
Pakistan's environment minister, Hamidullah Jan Afridi, said the event was part of a series of events being held to observe the national year of the environment.
"The government has set aside one billion rupees over a three-year period to protect these plants and help them survive," Mr Afridi said.
Mangroves grow in delta regions where the fresh waters of the river mix with sea water.
Experts say the new saplings will have difficulty surviving because of diminishing river water in the region.