Non-Native Tree Species in Northeast India

Dr. V. Ramakantha *

A Gul Mohur Tree

While touring the State of Jammu and Kashmir (way back in 1985 summer), I was greatly impressed by the splendid scarlet flowers of a tree that was growing in the in the premises of the Shankar Mutt in Srinagar, the capital city of the State. On enquiring, I was told 'Gul Mohur' to be the name of the tree. I assumed "Gul Mohur' to be its Urdu name, and thought it to belong to the State of J & K, and noted its name in my memory. Subsequently I learnt that this tree, which is now commonly seen all over India, has come from the forests of Madagascar.

Known to science as Delonix regia, this ornamental tree has no timber value whatsoever. It is not even good as a fuel wood. Its pods are not fit for human consumption, and even monkeys or crows do not eat them. When in many parts of India, where winter sun can be scorching, this tree sheds all its leaves, and it is not considered a great shade tree. If we grow this tree near our house, its surface running crooked roots pose problem to our compound wall, or if it is not grown considerable distance away from the plinth of our house, it would cause damage to our building. Come rain, and its weak branches may fall on someone's head, and it is not infrequent that this wind-prone tree itself falls.

In its original ecosystem in Madagascar Gul Mohur might be playing a vital ecological role, but in distant shores of India, its ecological benefits are question worthy. If this tree has medicinal value, I am yet to come across people who know about it.

Gul Mohur is not the only non-native tree species which fits into the above description. Sausage Tree (Kigelia pinnata) Tulip Tree (Spathodia campanulata), Monkeypod Tree (Samanea saman), Jacaranda (Jacaranda mimosifolia), Yellow Bells (Tecoma stans), Pink Cassia (Cassia javanica) are some of the recently introduced tree species that have ornamental value, but we derive little else from them. 'Exotic', 'alien,' 'introduced', 'non-indigenous', and 'non-native' are all synonyms for species that humans intentionally or unintentionally introduce into an area outside of a species' natural range.

Ecological studies have revealed that non-native species disrupt complex ecosystems, reduce biodiversity, jeoparadise endangered species of flora and fauna and degrade habitats. One Mr. Randhava brought out a book on trees with a frontal colour picture of splendid flowers of Gul Mohur, (published by the National Book Trust) and it caught the imagination of many of its readers.

I have been arguing that non-native trees should not be introduced without subjecting such species to serious scrutiny. Once, while delivering a lecture to forestry personnel, I was explaining the relevance of using native species in our ex-situ conservation programme, quoting over 42 international publications that advise us not to encourage species evolved in distant ecosystems. One of the participants said, "Why are you so much bothered about the place of origin of plants? After all, trees are trees, and all trees are beneficial".

"I fully agree with you", I said, "all trees are trees, but only fruits of few trees are edible for human beings, though monkeys can eat most of them. Similarly, we eat grains of wheat, paddy etc, but not that of Parthenium weed". As a faculty member it was unwise on my part to be rude, but could not help the outburst, for I expected a fellow forest officer to know better. I had placed myself in a precarious situation much earlier, while I was serving as a forest officer in the State of Karnataka.

In the year 1994, in the presence of the Head of the Department of forest I aired my displeasure about massive introduction of non-native species into Karnataka, especially in the Western Ghats region (where I hail from). This senior most forest officer of the state was having his dinner, and he got upset with what I said.

"What is a non-native species? Look at this", he said, stabbing his fork into a piece of potato in the meal, "this is a non-native species". He continued to show me other items on the plate, like chilli, tomato, cauliflower, capsicum and so many other vegetables that were a part of his dinner. He paused for a while for effect, and looking keenly into my eyes, asked me in a grand manner as to what was wrong with any of those items in his menu.

It was indiscretion on my part to press my argument further in the presence of so many other senior forest officers who had come to call on him. I was young and I was foolish. I put forth a counter argument. I said that all those culinary items that he showed were either annuals or biannuals, and not trees. Moreover, it was not the Government which introduced such plants.

Those delicious vegetables have won over the taste buds of all of us, and people grow them as it is economically rewarding for them to do so. In our case, the trees that we have introduced have not been tested for their usefulness vis a vis our native species, and despite the tag of 'fast growing species', that we bestow on some non-native species, it is far more rewarding to invest on suitable native species.

After a while, to my discomfort, someone whispered into my ears that the senior forester with whom I had such a wonderful discussion was the one who took the initiative of introducing Eucalyptus, a fast growing tree species from Australia; and being a powerful technocrat, if he minds, he could send me back to my parent cadre the very next day.

That senior forest officer was a great person. He simply changed the topic. I knew that all was well when he accepted my invitation to become an esteemed guest in my house for breakfast the next morning.

I am well aware that many exotic trees have been introduced into India right from the days of the Greeks (327 B.C.), and quite a few of them have got acclimatized and established in the original flora of the area. If I am right, most of the plants that were introduced in the distant past were of great economic value - Areca Nut, (Areca catechu), Coconut (Cocos nucifera), Tamarind (Tamarindus indica), Hummingbird Tree (Sesbania grandiflora), Cashew Nut (Anacardium occidentale) and Guava (Psidium gujava) are some such useful trees. They have become part and parcel of our life to the extent that few realise that they have had their origin in some distant countries. These trees cannot be compared with the mere ornamental trees mentioned above.

Millions of Gul Mohur, Sausage Tree, Tulip Tree and such other trees are grown in India. I have noticed those ornamental trees being grown in each and every State of India including the Northeast. The arid and semi arid regions of India may not host much of biodiversity, and in such places, if trees such as Gul Mohur are grown, I may not have serious concern. However, it pains my heart that we choose to grow such trees in Northeast India.

Northeast India is geographically 'gateway' for much of India's flora and fauna; and as a result, the region is one of the richest in biological values. This region has been the Vavilovian centre for origin for a variety of flowering plants. With vegetation ranging from tropical rainforests to alpine meadows and cold deserts, this region is considered to be the 'cradle of flowering plants.' Nearly 43 per cent of flowering plants recorded from this megabiodiverse country come from the Northeast.

Besides, the striking feature of Northeast India is the occurrence of many primitive flowering plants, some of which produce spectacular flowers, and thus, no less in ornamental value that are associated with the Gul Mohur and the like.

Introducing such non-native plants is like 'bringing coal to New castle'. As a large number of native species are on the verge of extinction, we should give priority to native species in all our ex-situ conservation efforts. The fact that some of the introduced plants have run amuck and have become alien invasive species, causing immense damage both ecologically and economically, should put an end to this argument.

In the sacred place of Kangla in Imphal very many native tree species are being grown, which is a welcome development. Similarly, the Institute of Bioresources for Sustainable Development (IBSD) is developing a complex at Hararou near Imphal with the sole aim of conserving the plant diversity of the region, which again is a praiseworthy effort.