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Why transplanting trees is a bad idea

By removing grass, plants or trees by their roots, the soil loosens up and gets blown or washed away and the roots wither and die

Written by Ranjit Lal |
August 8, 2021 6:48:38 am
treeThe green network: A banyan sending down prop roots (Photo: Ranjit Lal)

They are undoubtedly the most unglamorous parts of a plant, but without them no plant – tree, bush or grass – can survive. The taller the tree is the deeper will its root go. Its underground spread can be as much as three times the diameter of the tree’s canopy. Roots also serve as repositories of nutrients (which is why some roots, like sweet potato and beet, are so nutritious!), especially in winters when the tree above shuts down food-producing operations.

Significantly, they also anchor the tree or plant into the ground and are designed to withstand astounding amounts of force, be it wind or rain. Roots are categorised into various types – depending on their function and where and how they grow. Not all roots, for example, grow from the bottom of the plant, heading south, some – called adventitious roots – sprout from the trunk and branches and stems and may head in any direction!

The roots are specialised in providing all that the plant or tree needs. Heading the charge into the earth is the root cap, which, as it plunges down, sloughs off, leaving a slimy lubricant in its wake and revealing what’s called the apical meristem, which is kind of loaded with fresh root caps (I guess rather like fresh drilling bits), ready to elongate and dig on. Then, root hairs develop at the end of these to absorb the moisture and nutrients, and send these upstairs to the tree or plant!

Roots have power. They can split granite – and everyone knows that it is foolhardy to grow a fig tree too close to a house; it will insert its roots into the foundations, weakening the structure. Many historical monuments have been clasped by the python-like roots of fig trees of various kinds and are crumbling under the onslaught. Perhaps, one day, long-term time-lapse photography might be able to reveal how roots crack apart solid rock.

They are usually covered with mud, but roots are savvy. They can sense the force of gravity, and they can snuffle out sources of water and nutrients and sense obstacles in their paths. More than all that, they form a vital part of the plant’s intelligence and communications network. Root hairs cultivate fungi in a symbiotic relationship in what is called mycorrhizae. The fungi comprising a mass of threads called hyphae spread far and wide beyond the root network, supplying the plant with water and nutrients such as phosphorous, even making barter deals with other plants in the region. In return, it charges a hefty fee of up to 30 per cent of the plant’s sugar production. This has been dubbed the “wood-wide-web”. Roots can also sense what the plant is in need of: and will adjust its actions accordingly – growing slower or faster or deeper as the need maybe – or actively seeking out water, if that’s what is required. The plants and trees growing in arid, desert areas, like the notorious Prosopis juliflora (Vilayati kikar), may send its roots down more than 50 m, which is why it is such a pain to remove!

All roots do not grow underground. The prop roots of the banyan sprout from branches and are used as column supports for the tree: secondary thickening of these roots and of other “buttress roots” at the base of the tree, help to support the huge stupendously heavy structure. Alternatively, the almost thread-like adventitious roots of the coconut palm may extend in a mesh 8 m across, far wider than the crown, and there may be 13,000 of these holding the tree firm in gales and typhoons.

Some roots even grow at canopy level. In dense rainforests, where the canopies of trees form a kind of roof, dead leaves and detritus starts to collect and decompose. The roots of the notorious strangler fig (also adventitious roots), clasp themselves around a host tree and suck up nutrients in parasitical fashion, and eventually kill its host. I remember being stunned by one such in Corbett; all that was left standing was the strangler fig’s scaffolding with absolutely nothing in the middle.

Other roots grow upwards, from the ground or from the base of the plants. Mangrove roots grow this way and are equipped with high-quality filters, which remove the salt from briny waters.

Anyone who has tried to rip a plant out by its roots will know how difficult it is. The plant or sapling clings on its mesh of roots holding firm. This is just an indication of how important a root network is to hold the soil together. Which is why felling trees on forest slopes is an invitation to landslides after the first showers. As far as grasslands are concerned the same holds true – if you remove the grass by its roots, the soil loosens up and is quickly blown or washed away. Most roots love it where it’s dark and damp underground. Expose them to fresh air and sky and they will wither and die; which is why transplanting trees may not be such a clever idea after all.

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