SM Najmus Sakib
Native plant species in the country's protected areas (PAs), including Sundarbans, are under threat as a stunning number of invasive foreign plants have been detected inside the local flora reserves.
These invasive plants can endanger extinction of the native plant species and create a disorder in the forests or PAs' ecology and ecosystem.
A study by the environment and forest ministry has recently identified a total of 44 exotic plant species in the five PAs.
It also identified as many as 17 plant species as foreign invasive plants in the five nationally protected forest areas.
In Bangladesh, more than 300 exotic plant species are listed as either wildly-growing or cultivated as economic crops.
According to Bangladesh National Herbarium (BNH), invasive alien species (IAS) are plants, animals, pathogens, and other organisms that are non-native to an ecosystem, and which may cause economic or environmental harm or adversely affect human health.
The five protected areas are --Himchhari, Kaptai, Madhupur National Park and Rema-Kalenga and Sundarban East Wildlife Sanctuaries.
Seven plant species out of the 17 demonstrate IAS characteristics as a major category. These seven species are locally known as Assamlata, Tofani lota, Lajjabati, Sungrass, Kansh, Kachuripana, Mogkanta.
Mohammad Sayedur Rahman, a senior scientific officer of BNH and a key official responsible for the study, said IAS' growth is usually higher than the native plants'. Therefore, IAS can easily dominate any forest if it goes uncontrolled.
IAS plants like Assamlata, a fast-growing creeper plant, can rapidly cover native trees and cause obstacles to their getting sunlight.
And, lack of sunlight impedes native plants' growth, he explained, adding such situation can even cause extinction of native plants.
He, however, said such introduction of foreign plants is a very old practice and all the introductions are not harmful.
But, conservation experts said a few of the foreign plants are becoming invasive and causing worrying losses to the local flora and fauna.
Experts suggested that it is necessary to ensure conservation of the indigenous plant species and forest areas by fully identifying the alien invasive plant species in all 51 protected areas and others in the country.
Ecology and biodiversity conservation researcher Pavel Partha said alien species have the ability to compete with native species in the protected forest areas, change the ecosystem and disrupt the food chain.
He, therefore, recommended taking advanced measures, including early detection and screening of the foreign plants.
He alleged that some government afforestation efforts were directly responsible for the increasing number of foreign invasive plant species.
"Madhupur Sal forest in Tangail district is an example where some foreign invasive plants like Acacia, Mengi were introduced. The forest has been largely damaged due to introduction," he alleged, calling for "determining the damage caused by the IAS."
He demanded that the authorities investigate what is the origin of the IAS plants identified in the protected areas and who introduced these plants, and take action against those involved accordingly.
Native plant species cannot grow properly beneath these foreign plants as they prevent native plants from absorbing required nutrients from earth, experts said.
Alien plants like Akashmoni dry up groundwater level more than native species and cannot provide habitat for birds and animals, and they also cannot protect native biodiversity from natural disasters like cyclone in coastal regions, Partha added.
Former Chief Conservator of Forests (CCF) Ishtiaq Ahmed also emphasised finding out how those plant species came into being in Bangladesh's native forests.
"Sometime we introduce foreign species scientifically and native biodiversity adopted those plant species like Shegun, Krisnochura-they are foreign species but were adopted in our native biodiversity," he said.
He also said invasive plant species usually don't grow in native forests on their own.
Earlier, some of these trees were introduced to prevent degradation of land and for other purposes; but any such initiative has not been implemented now, he added.
The government says it has formulated five Strategic Management Plans for the proper management in conserving national forests and forest resources by eliminating them from the ecosystem and preventing their spread.
Sanjay Kumar Bhowmik, additional secretary of the environment ministry, told the FE that the study was carried out just to know if there exist any foreign invasive plants in the native biodiversity and their effects as well.
"We have been developing our strategy with technical support from IUCN and an expert panel consisting of university teachers will further study the effects of those invasive plants to preserve forests and biodiversity and take necessary steps accordingly to save our native plant species," he added.
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