The humble acacia from Oman is a real survivor

    23 Sep 2021

    The Omani ‘treeline’ is far from common, but the staunch Acacia, vancellia tortillis, or the Umbrella Thorn Acacia, adorns almost every sunrise, sunset, and landscape portrait, taken or painted, within the Sultanate, Oman Observer states.

    The Acacia was romanticized by Nadeem Aslam, writing “He led her back to the house, the perfume from the Acacia clinging to her. The djinn was supposed to live in the scent of the Acacia blossom, making themselves visible only to the young…” investing a mystique in that craggy tree, best seen stark against the sun or moon.

    The Acacia is a real survivor! Common to much of North Africa and the Middle East, it survives drought due to its remarkably long and aggressive tap roots, which reach deep below the ground to find water. Those same root structures and sturdy trunks also enable them to survive high winds, intense sunlight and heat, devastating floods, and the tree is also, quite amazingly, fire resistant while still rooted, with regrowth occurring almost immediately after bushfires. Even when the entire tree, above the ground, is cut off, or burnt to the ground, the subterranean root structure enables regrowth. Mature Acacias are also frost resistant, making them a tree for all seasons.

    Here in Oman, in Wadi Muaiden at the foot of Jebel Akdhar, are some incredible examples of the remarkably resilient survival qualities of the Acacia. With its significant rain catchment in the mighty Jebel, flooding in the wadi comes hard and fast, flashing down off the peaks to thunder across the old Highway 15 ford, across to the dam near Karsha, and onwards to the hinterland. The erosion caused by the flash floods is apparent in the images provided, as these Acacias have withstood thousands, even millions of tons of pressure, and the erosion of much of the terrain around them, sustained and held together by their amazing root structures, to see another day, or more.

    Myrmecologists, involved in the study, and science of ants are greatly intrigued by the symbiotic relationship between some species of ants and the Acacia. They point to the ubiquitous presence of ants living within the thorn and branch structure of the tree as having a cool environment, while in return, the ants defend the tree by stinging most animals that venture to graze upon their soft young thorns and branches. The ants also discourage other inhabitants from residence, thus offering further protection. Giraffes and camels, having greater height, are wider, though limited grazers of the canopy leaves.

    But the Acacia has another, incredibly unique defense system. When the canopy is grazed, a poisonous, foul tasting alkaloid substance is released from the thorns, rendering the leaves inedible, but not only that. The resultant chemical leaks into the environment and ‘warns’ the other Acacias nearby. They then activate their toxic release, and the unpalatable trees are then safe from heavy grazing. Goats and camels do however, graze on the seed pods, lichen, moss, and windblown tree growths. A gnarly, knotted, difficult wood to work with, it was a staple for use during biblical times for furniture, and keepsakes, and is believed to be that used in the construction of the Hebrew tabernacle of the old faith.

    Elizabeth Barrett Browning, who had such a way with words “A great Acacia with its slender trunk and overpoise of multitudinous leaves, in which a hundred fields might spill their dew and intense verdure, yet find room enough, stood reconciling all the place with green.”

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