High Time to Formulate Policies to Tackle Alien Species in India, says experts

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It’s time for an all-out war with the aliens, at least in the protected forest areas, but we lack policies, says a group of conservation scientists in the country. Invasive Alien Species (IAS) of plants are the second largest threat to the diversity of the forests, behind habitat fragmentation, but the conservation policy makers are yet to swing into action to tackle the issue, alleges a group of scientists while reviewing the status of IAS in the country and related conservation laws in India.

Lanatana Camara flowers
Image courtesy: Obsidian Soul/Wikimedia Commons

According to an article written by them in the Current Science journal, plants like Chromolaena odorata, Lantana camara, Mikania micrantha, Mimosa diplotricha and Parthenium hysterophorus are some of the major invasive alien plant species in India which are spreading rapidly in protected areas (PAs), suppressing the growth of the native flora. The alien menace has affected birds, animals and has not even spared the tribal populations depending on forests, it says.  “Large numbers of forest dependent communities still depend on forest resources and their livelihood is at stake due to pervasive landscape alteration by major IAS in different parts of India,”, says the article.

Lack of policies and distorted interpretations

Though the threat and impact are high, most of the protected areas in India do not have a clear and active eradication programme to tackle IAS, mainly because of lack of awareness among wildlife officials and their twisted interpretation of the conservation laws in the country. Wildlife (Conservation) Act, 1972, which is the major legislation regarding protected areas in the country, prohibit harvesting or removing any plant or animal materials from the PAs. This is raised as a major reason by protected area managers for not taking active eradication programmes against invasive plant species.

Chromolaena odorata
Image Courtesy: Ashasathees/Wikimedia Commons

Moreover, the Protected Area managers and policy makers are yet to understand the importance to eradicate IAS. Most often, the notions of the officials often end up encouraging exotic species. “Their (PA managers’) species selection for plantations is based on three criteria: (a) fast growth, (b) good timber value and (c) unpalatability to game species. These criteria encourage the planting of exotic species …….in effect replacing one IAS with another alien species”, points out the write-up. According to it, some of them even think that IAS likeLantana are good for the animals since it give them cover to hide. But they forget that “such a role was played by indigenous understorey species prior to being replaced by vast swathes ofLantana, now dominant in many PAs”, it says.

How to eradicate Invasive Alien Species?

Removal of invasive plants from an area of infestation is not an easy job, since most of them show extra-ordinary abilities to reestablish themselves in the areas. “The seed bank of the major IAS remains and hence reinvasion occurs rapidly. Some IAS, such as Lantana, which are buried deeply can be stimulated to germinate when exposed to light and fire”, says the experts.

Presently, whatever nominal eradication programmes run in some protected areas are very narrower in their nature since they focus only on removing the IAS for the purpose of making fire lines. However, there is a need to develop early detection mechanisms to spot the menace when it begins so that the eradication is easier, constant monitoring to prevent spread of the IAS and resulting forest fragmentation.

Lantana Camara growing rapidly suppressing native plants in a farmland in Kangra District, Himachal Pradesh 

Manual removal is the best practice so far observed to tackle the menace, according to the article. Though it is very effective in small areas, it may not be so for large areas since the estimated cost of manual eradication is anything between 4000 to 5000 Rupees per hectare. But implementing any such measures on a wide scale may not be possible in the absence of legal provisions to facilitate it.

However, there is a possible way out, according to the experts. According to them, the issue can be raised with the Supreme Court appointed Central Empowered Committee (CEC) which can submit recommendations and suggestions to review existing conservation legislation to tackle the issue. So the ball is in the court of conservationists in the country. “We see a compelling case for scientists/managers to approach the CEC for clear guidelines and exemptions regarding programmes for the vigorous control and removal of IAS from the PAs.”, says the article.

North American weed spotted in India, could be major threat to agriculture and forests in future

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If the initial hints are anything to believe, the farmlands and forests in India have a brand new invasive threat from a rarely reported foreign plant species native to North America. A recent research correspondence published in the Current Science journal claims to report the plant for the first time from India and argues that the plant can have tremendous invasive potential.

Western ragweed (Ambrosia psilostachya)
Image courtesy: Krzysztof Ziarnek Kenraiz (Wikimedia commons)

 According to the researchers, the plant is presently reported from farm lands in the M. Bevinahalli village in Turuvekere taluk of Karnataka. On close examination and surveying the literature, the researchers were able to identify the new plant as Ambrosia psilostachya. Though the plant resembles its close relative Ambrosia artemisiifolia which is found in India, it is actually different, says the correspondence. 

Its Indian variety, Ambrosia artemisiifolia, was the only member of the genus hitherto reported from India. According to the correspondence, the new weed is native to North America and is known as perennial rag weed or western ragweed in North America.

New invasive plant threat in India

The research note warns that the weed has tremendous capacity to spread very rapidly and is known to cause allergic reactions in Humans. “If the weed is not controlled now, it may create a difficult to control situation once it proliferates from the location of present report”’ says the correspondence. 

According to the correspondence, the weed has not only invaded finger millet, mulberry, coconut and areca nut cultivation  but has also conquered the cattle pastures which have affected animal husbandry of these villages. The correspondence also notes that the plant has seriously affected local flora, by replacing local grass varieties, thus decreasing fodder availability. 

The plant is capable of spreading to large areas through extensive vegetative reproduction through underground rhizome like roots and stolon (part of the plant which makes new plant).  Though the plant has been present in some villages in Karnataka for the last 15 to 20 years, it is not yet clear what restricts it from spreading to other places.

 According to the researchers, since the plant does not have parts which supports seed dispersal through wind, the plant has not yet started spreading to other places. It is also not clearly known at this point if all the seeds produced by the plant are viable or if they exhibit any type of dormancy.

Though, there are not many issues reported about this plant expect its rapid invasion of farm lands in Karnataka Villages, reports from other countries indicate that the plant can cause allergic diseases in humans. “The species is said to be responsible for causing severe allergenic diseases in human beings in the United States”, says the correspondence.

The North American Connection

The plant is actually native to North America and the way in which it has reached Indian farmlands is still unknown. Though some speculates that the seeds could have been brought to India by migratory birds that use the seeds and other parts the plant for making nests, the connection is yet to be scientifically proved.

Though contaminated food grains are a usual way in which invasive plants reach farther places -as in the case of Lantana, a notorious weed in Indian forest- that may not be the reason for the spread of the present weed. “The introduction of the species through contaminated food grain may not be possible, as the weed is localized only in these villages in Karnataka”, says the paper.

The plant has already spread to parts of South America, Europe, New Caledonia, Japan, Taiwan and Australia. The researchers do not rule out the chances that the seeds reaching India from either of these places.

Weed control measures

 The presence of root buds, horizontally running rhizomes and dense root ramification makes the plant difficult to manage and eradicate. Periodical manual removal, shallow plowing before passing cultivator in farms has been recommended as a control measure. According to the note, if repeated control measures are taken, the weed can be controlled in 4 to 5 years from the country with its present restricted proliferation.

 M. T. Sanjay  and T. V. Ramachandra Prasad from the Directorate of Weed Science Research Centre, University of Agricultural Sciences, Bangalore, R. A. Sharma from Directorate of Weed Science Research, Indian Council of Agricultural Research, Jabalpur and R. R. RAO, from Bangalore co-authored the correspondence.

Read more on IBT's coverage on invasive species in India.

Indian plant Ricinus communis among invasive threats to world’s second largest lake

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According to a new report published by the Invasive Species Initiative under the International Union for Conservation of Nature (IUCN) , the Caster oil plant which is native to India is one of the invasive plants that raise a major threat to the second largest and second deepest lake in the world – Lake Tanganyika - shared by  Burundi,Zambia,Tanzania and Democratic Republic of the Congo (DRC) .

Dense Growth of Ricinus communis

The report says that Ricinus communis, commonly known as Castor oil plant in English and Kadalavanakku in Malayalam, is a usual plant found in India. The plant, according to IUCN report, has shown invasive nature in other habitats and is a major invasive threat to Lake Tanganyika.

Lake Tanganyika has at least 250 species of endemic cichlid fish and many endemic water plants. But the presence of invasive plants around the lake is threatening the natural habitat of the lake as well as the existence of native fauna and flora.

The invasive zeal of Ricinus communis

Biological invasion is a wide phenomenon seen across the globe. It happens when a non-native species is introduced to a new environment, and it spreads virulently to cause damage to native organisms. Ricinus communis, due to its invasive nature, now has spread across all the tropical regions, says the report.

According to the study, the invasive nature of the plant makes it capable of displacing native plant species from a habitat. The impact will be more visible in the case of riparian areas and drainages. The seeds of the castor oil plant also give the plant some upper hand among native plants, shows the report.

The Castor oil seeds have a worthy appendage known as caruncle which attracts ants as the major seed dispersal agents for the plant.  Moreover, the seeds are among the first to germinate after a fire season, allowing the plant to have a competitive advantage over other native plants over the fight for resources.

Lake Tanganyika
Image courtesy : Google Maps

The plant is a fast growing suckering perennial shrub and often attains the size of a small tree. Due to this nature, when they colonize in already disturbed habitats, they grow faster, often shade over the native plants and seedlings, gradually weakening the strength of the native plant species.

Major reasons for the spread of the plant

According to the study, the ornamental plant trade is a major source through which the plant has got its grip around Lake Tanganyika . The practice of cultivation for extracting Castor oil is also a reason, points out the study. Apart from these, road building machinery, earth moving equipment and dumped garden waste also spreads the seeds of the plant.

The study which is preliminary in nature is the first of its kind to take place at Lake Tanganyika. It has listed 31 invasive plants which are raising serious threat to the water body.

The lone bat species in Kutch district threatened by serious habitat destruction near Hamirsir Lake

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Bhuj is gradually recuperating from the devastating earthquake which claimed 12290 lives in 2001. Now, the developmental activities are at full swing, the wreckage is being replaced by new constructions. However, the developmental and rehabilitation activities around the Hamirsir lake in the Kachch district is adversely affecting the population of the lone bat species in the district in the Indian state of Gujarat, the Indian flying fox (Pteropus giganteus).

Indian flying fox (Pteropus giganteus)
Image courtesy: Wikimedia Commons

Fondly called as 'Vagol' in local Guajarati, the bat species is the only large-sized fruit bat species found in Kachchh District. According to a research correspondent published in the latest issue of the Current Science Journal, the bat species has been using the small vegetation patches near the Harmisir Lake as a major roosting site. However, it is facing serious habitat destruction due to cutting of large trees in and around the lake as part of the reconstruction and developmental activities, says the correspondence reported by researchers at the Institute of Desert Ecology, Gujarat.

“The reconstruction and developmental initiatives have resulted in the cutting down of large trees which had provided shelter to the flying fox population in the past.  The natural habitat like forest patches and larger trees are disappearing due to rapid industrialization, urbanization” says the correspondence.

Disturbance from Laser shows

Moreover, the tourists activities in and around the lake are also taking a toll on the Indian flying fox population here. The influx of tourists and the resulting vehicular traffic are additional threats. According to the correspondence the laser light shows during the ‘Kutch Carnival’, a tourist fest, is also disturbing the Indian Flying Foxes in the area.

According to the correspondence, the wide presence of an invasive plant Prosopis juliflora, is also posing a major threat to the natural habitat of this bat species in Kutch district.

Conservation significance of Pteropus giganteus in Kutch

Earlier studies have shown that bats usually play a major role in pollination and seed dispersal of many plant species. Since it is the lone bat species in the district, it will be crucial in the pollination of many plants in the area. The disturbances caused to the habitat of the organism will thus take a toll on the population of many plants here thus bringing down the quality of the eco system, points out experts.

Though Indian Flying Fox is categorized under the Least Concern group in the Red Data book of IUCN, experts point out that the population trend of this organism is decreasing.

Calling for immediate attention towards the conversation statusof bats, the correspondence says that the bats have been given a least conservation priority in the area.  

“The time has come for the conservation of all animal groups, including the Flying Fox for maintaining ecological balance and conservation of biodiversity”, says the correspondence. 

Do you think conserving Indian flying foxes in Kutch as important? Share your views in the comments. 

Invasive plant Acacia dealbata reported from the high altitude Himalayan forest of Kedarnath wildlife Sanctuary

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Indicating an early sign of proliferation of invasive species in the Himalayan forests, as expected to happen during the phenomenon of global warming, a group of researchers has reported the presence of Acacia dealbata - an invasive alien plant - from the interior of the high altitude protected area of Kedarnath wildlife sanctuary situated in the Indian state of Uttarakhand.

Acacia dealbata in bloom
Photo courtesy :Wikimedia Commons

The team has spotted the plant at an altitude of 2200 from the mean sea level, which makes it the first report of the species from such a high altitude of Garhwal Himalayas, says a research correspondence published in the Current Science Journal. It also turns out o be the first record of the species from the large protected area of Kedarnath Wildlife sanctuary.

The presence of the invasive plant can have serious impact to the Himalayan forests considering the invasive nature of the plant, says the research correspondence.

"Temperature tolerance level of some alien species is very wide, with global warming the temperature fluctuation has become wide giving these species ample scope to survive", says Jahangeer A. Bhat, Researcher in Forest Ecology at  H.N.B Garhwal University.

According to him, there is no clue on how this plant reached to this elevation. "We guess it might be  through some food source or something else", he said.

"There was no human settlement near this plant patch and neither we found this species below this elevation nor above this elevation. these plants were only present in a patch at the reported altitude", said the research team which found the plant.

Jahangeer A. Bhat, Munesh Kumar, Ajeet K. Negi and N. P. Todaria at the Department of Forestry and Natural Resources, HNB Garhwal University, Srinagar-Garhwal have reported the species, as per the correspondence published.

The plant is already declared as an invasive species in the Indian Himalayan region, while it is reported as a problem species in Portugal, northwest Spain, New Zealand, France and Italy where it is found to be replacing native plant species and taking a high toll on the biodiversity of indigenous plants.

Plants of Acacia genus have been notorious for their ability to invade native forests and replace grass lands. They are also found to increase water loss in riparian zones and thus gradually change the ecological nature of the area.

However, it is ironic that social forestry wings of many state forest departments were once encouraging planting Acacia plants in public places as part of aforestation attempts. The adverse consequences of the plant like its potential to drain up groundwater tables and to produce allergic pollens during flowering season were understood later only.

However, India is still to have a unified central policy on how to manage invasive species in its native forests.

Is there any invasive species raising threat to native plants or animals in your area? Please share us the information here.

Meanwhile, read more on IBT's coverage on invasive species in India.