Registered with the Registrar of Newspapers for India under R.N.I 53640/91

Vol. XXVII No. 7, July 16-31, 2017

Tackling a proliferating shrub

The MNS recommends

Prosopis juliflora (a mesquite, T.Seemai Karuvel or Veli kaathaan) is being destroyed indiscriminately in the State, according to environmentalists. The High Court directed the Forest Department to constitute a Committee and to advise it on the scientific method to be followed to eradicate this plant. The Madras Naturalists’ Society submitted a representation to the Committee. Summarised and with its recommendations, it states the following:

The plant Prosopis juliflora is widespread in the plains and, possibly, in the coastal regions of Tamil Nadu but is not native to Tamil Nadu. It is a New World species. Prosopis juliflora is understood to have been introduced deliberately by human agency in parts of India in the 20th Century.

A large variety of birds, mammals, reptiles and insects benefit from the species in numerous ways. Obtaining food, protection and nesting sites are among the uses. Just like any other vegetation, Prosopis juliflora serves as a carbon sink and performs various ecological services. Villagers use the thorns and branches for their fuel requirements and for charcoal production. Prosopis juliflora is also used as a live fence in places.

The plant has come up and proliferated mainly in areas that have been cleared of vegetation and left undisturbed subsequently. Apart from these areas, Prosopis juliflora grows in large stands only where it is exploited by humans. Prosopis juliflora has not come up in other areas that are under intense human management (areas such as agricultural fields, where there is constant maintenance of the vegetation). It has also not invaded vegetation-covered areas in forests. On the one hand, when cleared land is left fallow, a situation is created where Prosopis juliflora may occupy the entire land quickly. On the other hand, the dominance or survival of Prosopis juliflora may only be temporary. Madras Naturalists’ Society members have recorded instances of significant mortality of Prosopis trees growing in water-logged conditions.

Wholesale removal of the plant from the State in a short time span is not feasible. The calls for removal of Prosopis juliflora are based on certain assumptions that may not be valid:

(1) That removal will result in re-occupation by native plants and animals;
(2) That the water table will recover once Prosopis juliflora is removed; and
(3) That threats to human health will cease upon eradication.

The observations of the members of the Madras Naturalists’ Society indicate that Prosopis juliflora is so resilient that any success achieved by extensive removal will be purely temporary as it will bounce back quickly, rendering the efforts futile.

However, if Prosopis juliflora is removed under a restoration initiative carried out in a well-planned, phased manner, using ecologically friendly techniques, it will be successful and give long-term benefits.

Recommendations

Restoration of the original native vegetation in any part of the State is desirable in that this will relieve anthropogenic stresses on the environment and biota. Prosopis may be removed under a restoration initiative carried out in a well-planned, phased manner, using ecologically friendly techniques. The Madras Naturalists’ Society recommends that any Prosopis removal adhere to the following guidelines and prescriptions:

-Stretches of Prosopis should be allowed to stand and natural succession processes allowed to take place so that the Prosopis is replaced by local species over time without human interference.

-Fresh growth of Prosopis must be discouraged. The strategy should be to encourage native vegetation and species that originally occupied the site in question. Thus, removal of young Prosopis plants should be achieved by introducing native species that will displace the Prosopis and not by directly killing the introduced species.

-The use of manure that may contain Prosopis seeds should be discouraged. This will encourage the introduced species to spread.

-Clearing of native vegetation of any kind should be stopped. Such cutting may create conditions conducive for colonisation by Prosopis, apart from destroying habitats.

-Old, standing Prosopis trees surrounded by local plants or intertwined with climbers should not be removed. Together, the plants form little ecosystems. Clearing will damage these living systems.

-If any Prosopis juliflora plants are identified for removal, a study should be conducted to determine if any animal species are deriving any benefit from them. Prosopis should not be removed if the survival of any plants or animals is affected.

-The reasons for water scarcity should be identified systematically and scientifically. Changes in the irrigation pattern or water usage in the area may have changed. Prosopis juliflora should also be studied scientifically to determine whether it affects the water table.

-Research should be conducted to verify whether any part of Prosopis juliflora or any vapours discharged by it are toxic.

-Prosopis growth that is being continuously managed for fodder and fuel (wood, charcoal) should not be removed. Removal will affect local economies and livelihoods.

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