In the Mangrove, a one-stop shop
The nation’s fragile and ecologically rich mangrove forests have been under pressure from human exploitation for a lot longer than many people think.
Most have heard the warnings from environmentalists that the multibillion-dirham developments along our coastline are causing damage to the warm, shallow mangrove flats that act as nurseries for fish and other wildlife but archaeology experts will tell you that vast areas of mangrove forests were felled by the country’s earliest inhabitants thousands of years ago, perhaps wiping out an entire species.
“We have this idea of the past as an idyllic time when people lived in complete harmony with nature,” said Dr Mark Beech, the head of the cultural landscapes division at the Abu Dhabi Authority for Culture and Heritage. “But the truth is that humans have been affecting the environment for as long as they have been on earth.”
Mangroves cover about 50 square kilometres of the country. However, fossilised charcoal and animal remains discovered by archaeologists show that mangrove species were once more diverse and spread across a larger area.
The exact area covered by mangroves in the past is not known, said Dr Beech. “All we can say is that there are areas where there were mangroves in the past where there are none now,” he said. “People exploited the mangrove forests and we know that from archaeological remains.”
Thousands of years before the coming of the waterfront villas, hotels and marinas being developed today, large areas of forest were cleared to provide material for houses, boats and even household items. “In prehistoric times, people made many more things from wood,” said Dr Beech.
The trees were also used as firewood. The need for fuel intensified with the Bronze Age, which began around 3,200BC, when people started smelting tin and copper ores to cast bronze – and, said Dr Beech, “people needed an awful lot of wood for fuel”. What is today the UAE and Oman was then an area occupied by people actively involved in metal work. A large proportion of the bronze produced was traded with Mesopotamia, one of the most advanced civilisations at the time, which required large quantities of the metal.
The proof that thousands of years ago such activities occurred here, and that mangrove wood was essential for the smelting fires, can be found in fossilised charcoal remains in Ed-Dur, Umm al Qaiwain and Tell Abraq, on the border of Umm al Qaiwain and Sharjah. The remains, said Dr Beech, told the story of people long gone and an ecosystem that had vanished.
The sole mangrove species now growing naturally in the UAE is Avicennia marina, popularly known as the grey mangrove. However, the ancient charcoal remains suggest that the mangrove forest once hosted at least one other swamp tree species that scientists have identified as Rhizophora or Bruguiera.
“According to our data, the Rhizophoraceae [family] would have disappeared from the Arabian Gulf sometime between the first centuries of our era and the present,” Dr Margareta Tengberg, a lecturer in archaeobotany who has participated in archaeological excavations in Egypt, Pakistan, Bahrain, the UAE, Syria, France and Denmark, wrote in one paper.
“In fact a progressive decrease of the relative frequency of the Rhizophoraceae is already noticeable in the charcoal record of Tell Abraq,”
The decline happened over hundreds of years. Dr Tengberg wrote that while Rhizophoraceae represented almost 60 per cent of identified species for the period between 2,500BC and 1,300BC, its presence shrank to only 25 per cent during the Iron Age, from about 1,300BC to 400BC.
Dr Beech said that this gradual decline suggested human exploitation to a point when the species become extinct. And there was a good reason why the ancient people preferred Rhizophoraceae to the grey mangrove. The former, he said, made better boats and also burnt more effectively.
But besides human exploitation, nature could have played a part in Rhizophoraceae’s disappearance. The Arabian Gulf waters, said Dr Beech, were less saline in the past. The salinity increased gradually and this affected the marine environment and species including the mangrove forests. The genus Avicennia grows so well because it has a high tolerance of saline water. Rhizophoraceae trees, on the other hand, were more sensitive to high salinity and, ultimately, were unable to cope.
Even though Avicennia was able to survive, its range has been greatly reduced. Mangrove forests are smaller compared with those of ancient times. Apart from charcoal remains, scientists have also discovered the fossilised claws of a swimming crab in areas that are now desert. The claws, said Dr Beech, preserved very well and many of them were discovered at various archaeological sites in the country, including in Iron Age deposits at Rafaq in Wadi al Qawr, 20km away from Kalba, and also in Kush in Ras al Khaimah.
The fossil has been identified as Scylla serrata, which today is widespread in the Indian Ocean and the western Pacific. The creature, said Dr Beech, was the largest of the swimming crabs which lived in mangrove forests and reached a weight of up to 2kg.
Until recently, when one specimen was observed in the northernmost tip of Ras al Khaimah, in a mangrove lagoon near the Police Club, naturalists thought the crab was missing from the Gulf. The archaeological evidence suggests that the crab was more common in the past, so much so that it was a staple of the local diet.
http://www.thenational.ae/article/20080513/FRONTIERS/848672718/1036 |