The invasion of ‘banphanda’
Problems caused by invasive alien species (especially plants) have been increasingly reported from different ecosystems throughout the country in the last decade, experiencing differing degrees of invasion. They pose a threat primarily to biodiversity by influencing and displacing native species in their home range. In addition, they are hurting the economy and the health of humans and cattle.
According to an IUCN-Nepal report of 2005, out of the 166 alien plant species recorded in Nepal, 21 species are problematic with respect to the local environment and the livelihood of the people. Among them, Jal Kumbhi and different types of Banmara and Banphada are ranked as the most problematic. The Jal Kumbhi (water hyacinth), which has now spread to almost all the lakes in the Tarai and Mahabharat regions, has been affecting the tourist industry and fisheries seriously. The Lahare Banmara (mile-a-minute) has been killing other plant species, especially trees, by strangling, blocking sunlight and producing plant inhibitors.
Similarly, the Banphada (lantana), which is known to produce dense under storey vegetation and plant inhibitors, has been suppressing the growth and establishment of other plant species. An additional problem is the fact that the fresh plant and seeds of many alien plant species are toxic to cattle and humans. The Banphada and Thakal (Argemone mexican) are toxic to cattle. The seeds of the Thakal enriched with toxic oil causes lethal dropsy in humans and cattle.
Most of the alien species recorded in Nepal compete with native species for resources and space, and are either unpalatable or less preferred by cattle. Besides influencing native species, they have already caused immense losses to agricultural and pasture lands and forests. The marginal and main lands in these areas are densely populated with the invasive alien species making these areas less productive and unsuitable for grazing. Until now, they have created problems especially in the lower hills (Mahabharat) and the Tarai where some species are confined to specific areas; for example, the Lahare Banmara occurs from the central to the eastern Tarai in the country.
Nepal has a long history of introducing non-native (alien) species to improve agro-forestry production and for recreational use. Some alien species have already become naturalized and make up an integral part of their ecosystems in which they have already proven to be essential to the livelihood and economy of the country. Maize, tomato, potato, papaya, guava, marigold, mirabilis and bougainvillea are among those species, and they have not caused any obvious problems in the environment where they have been introduced.
In contrast to this, some alien species grow very fast and affect the native biodiversity and the livelihood of the people in a negative way. These are called invasive alien species. According to the Global Invasive Species Programme, such invasive alien species are a major reason behind the decline of native species in their home range and changes in the local environment resulting in a great threat to native biodiversity.
In addition, they are a source of hybridization with native species (gene pollution), major losses to the economy, water loss from watersheds and a vector for many diseases, including human ailments.
Invasive alien species are much more difficult and costly to control once they establish their presence because of their better survival strategies like rapid population growth, high dispersal ability by wind and water and tolerance of wide environmental conditions. For example, the Jal Kumbhi which has been difficult to remove from almost all the lakes where it has spread. Nepal’s efforts in formulating a legal framework (for example, the Plant Protection Act which came long ago in 1972 to provide effective laws and quarantine regulations) and signing many international conventions (for example the Convention on Biological Diversity), rather than doing scientific studies to find effective techniques, have not been sufficient to control them.
An explosive population growth has increased trade and transportation across the open border, which can be a reason that it has been difficult to implement the available laws, enhance public awareness and implement the use of local resources to control invasive alien species. A globally shared knowledge now is that measures applied at the initial stages and involving local communities are more effective in controlling them. In addition, most of the invasive alien species, especially the plants found in Nepal, exhibit air or water dispersal mechanisms, which make laws against introducing them to new areas worthless.
Public awareness and community involvement are, therefore, necessary to locate and control these species. The general public may not be aware of the harm being caused by the alien species on ecosystem functions. They may complain of declined production, but may not know that invasive species compete with their fellow crops and lead to their loss. Hence, the need for education of the general public including policy makers is a growing urgency. A conscious public would inform the responsible authorities of the occurrence of any invasive species, which they should try to remove or control by using local resources and try to use local and non-invasive species to prevent their reappearance. In support, they should provide alternative ways to maintain the local production of food; otherwise the local community would not withstand the temptation to use invasive species to meet the growing need for resources.
Scientific cooperation to reduce the use of invasive alien species is necessary, for example, to conduct studies regularly to find which alien species is becoming invasive in our locality and find alternative native or non-invasive alien species that can be used to produce the necessary food. The responsible authorities, therefore, have a catalytic role in controlling invasive alien species.
Despite its small area, Nepal is globally known for its rich biodiversity. It is, therefore, important to control the spread and effects of such species at an early stage during their establishment process. Any further passivity and lack of initiatives may have a serious impact on native biodiversity.
Posted on: 2011-09-14 09:15
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