A new problem is emerging inside the country’s most famous wildlife conservation area, Chitwan National Park.
It is an invasive weed – parthenium.
The invasive weed is spreading at an alarming rate to different parts of the park and if not controlled in time it should be a cause for concern to wildlife.
Conservation biologist Baburam Lamichhane said parthenium (Parthenium hysterophorus) is spreading rapidly in various parts of the park.
âDuring this year’s rhino census, we found that the weed had spread to different parts of the park, mainly rhino habitats,â said Lamichhane, who is also the head of the Conservation Center for the biodiversity, Sauraha, under the aegis of the National Trust for Nature Conservation. . “The invasive plant has reached areas where it has not been seen before.”
Invasive plants are non-native species and tend to spread uncontrollably, with the potential to negatively affect local ecosystems. Invasive alien species are considered one of the greatest threats to biodiversity as they adversely affect native plants and the ecosystem as a whole, can also cause huge economic losses and harm the environment and to human health.
According to the United States Department of Agriculture, invasive species have contributed to the decline of 42 percent of endangered and threatened species in the United States, and 18 percent of endangered or threatened species in the United States. United States, these invasive species are the main cause of their decline.
According to Lamichhane, the weed has already swallowed up five to seven percent of all rhino habitats, which he says is a worrying sign.
Parthenium, also known as carrot grass, is native to North America. The annual grass can grow 1 to 1.5 meters tall, with numerous branches developing from its upper half and an erect stem. It invades disturbed and barren areas and pastures.
âLoose and exposed soil with adequate light is favorable to its growth. Newly plowed land, for example, âLamichhane said. âWhen counting the rhinos, the grass had been recently cleared and the land was still dry, so this invasive plant had not fully grown. When we clear bushes as part of grassland management or to create trails or roads, it opens up the soil, creating a favorable condition for its unrestrained growth.
According to Lamichhane, a parthenium plant can produce around 30,000 seeds and that can easily spread in all directions, resulting in its massive spread.
Once it has spread over a large area, it can cause massive damage to the local environment and other native species.
Parthenium has been identified as one of the ‘100 most invasive species in the world’ by the IUCN, as it has become a serious agricultural and grazing weed in parts of Australia, Asia, d ‘Africa and the Pacific Islands where it affects crop production. and cattle.
Studies have shown that parthenium has become a major weed in field crops in more than 45 countries and that in Australia it causes yield losses of several million dollars each year.
Parthenium is estimated to cost the Australian beef industry $ 16.5 million and agricultural industries several million dollars annually.
In Nepal, this is not the first time that the weed has been reported inside Chitwan National Park.
âThe first time the weed was reported was in 2012-13. But around this time the weed was found in small patches of land, mostly along the roads, âLamichhane said. âSo it wasn’t a big headache back then. But since last year, its growth has been rapid. Now it has emerged as a serious problem in the park. “
Before parthenium, Chitwan National Park had to deal with another invasive alien species: Mikania micrantha. The species had grown so aggressively that it was considered one of the main challenges for rhino conservation in Chitwan National Park.
At one point, Mikania micrantha, which was first reported inside the park in 1963, was responsible for 44% of degradation of rhino habitat inside Chitwan National Park. This weed suppressed forage grass growth and prevented tree regeneration, according to a 2o16 study.
In 2010, then Prime Minister Madhav Kumar Nepal traveled to Chitwan to participate in a campaign to uproot Mikania micrantha.
âMikania micrantha has kind of been in control over the last few years. The invasive species becomes naturalized in the local environment where it is attacked by other insects and fungi, slowing its rapid growth, âsaid Lamichhane. âIn addition, it also has to compete with other local plant species for its survival, so its invasiveness has decreased. In 2008, 2011, 2015 and 2021, when we took rhino counts, we found that the spread of Mikania micrantha had significantly reduced. “
In the last rhino census, we found that Mikania cover had dropped to about 35 percent of rhino habitats.
However, experts like Lamichhane fear that parthenium could cause similar damage and havoc if not contained in time.
âGrasslands provide food for wild animals. However, when native green plant species have to compete with invasive plants like mikania or parthenium, those invasive plants win out, âLamichhane said. “Such a situation means no food for the animals because they do not feed on these weeds.”
Chitwan National Park, home to Nepal’s largest rhino population, managed to increase its rhino numbers in the last rhino census which ended in April. The one-horned rhino population inside the park was 694, an increase of 89 rhinos from 605 rhinos in 2015. The growth has been attributed to conservation efforts and habitat enhancement, among other factors.
The current seven percent parthenium coverage may seem trivial at the moment, but it may appear to be a Mikania-like problem in the future if not managed properly, Lamichhane warns.
âUprooting is the only way to get rid of the weed. But this would not be possible for large surfaces. Therefore, at least in animal habitats and grasslands, weeds must be uprooted without delay. To remove weeds from larger areas, a special plan must be drawn up. ”