Chitwan National Park of Nepal, a World Natural Heritage Site and a habitat of an endangered one-horned rhino has been facing the problem of multiple invasive plant species. Chromolaena odorata (locally called "Banmara") and Lantana camara have been present in the Park for some time and in the last 10-25 years, Mikania micrantha (locally called "Lahare Banmasa") has been rapidly expanding in grasslands, spring sides and forest fringes which are the key habitats of the rhino. The negative impact of Mikania on forage supply to and roaming behavior of the rhino has already been noticed. The next emerging threat of alien invasion to Chitwan National Park is parthenium weed. Mostly confined to urban and peri-urban areas of Nepal until a few years ago, parthenium weed is now expanding to natural habitats including national parks. A few years back, parthenium weed was confined to the Park‟s buffer zone areas at Sauraha, the main tourist destination popular for the sightseeing of wild life during elephant rides.
|Luxurious growth of parthenium weed (white flowering) between the elephant shed and forest.|
Currently small to large patches of parthenium weed can be found inside the Park area along the elephant ride routes, vehicle tracks and trails, including the grasslands with short grasses. The area around the Elephant Breeding Centre, which lies in the buffer zone, is the most heavily infested site. Inside the park the abundance of parthenium weed is not yet at a damaging level (at least in the northern side of the park where I visited twice in 2011), but it appears to be expanding rapidly with possible adverse impact in near future to forage supply for herbivores.
Mapping the occurrence of parthenium weed in the entire Park area is, however, still to be done. Conservation officials at Biodiversity Conservation Center of National Trust for Nature Conservation (NTNC), a major stakeholder responsible for research and management within the Park, have noticed the arrival of parthenium weed inside the Park but are not yet well informed upon its possible negative impacts.
|Distribution of copies of parthenium weed ID kit among remote communities in Nepal||Author standing alongside a parthenium weed roadside infestation|
The Center has mapped the distribution of Mikania twice but has not considered parthenium weed yet in this mapping approach, and also has no immediate management plan to tackle this noxious weed. Fortunately, a leaf feeding beetle Zygogramma bicolorata has already reached to buffer zone area (observed at Elephant Breeding Center in July 2011) but the population of beetles is still not large enough to cause massive defoliation of parthenium weed.
In December 3-9, 2011 Professor Steve Adkins visited the Tribuvan University, Kathmandu, Nepal and presented a seminar on invasive weeds with a focus on parthenium weed. Following a series of field visits and meetings, it was decided that an appropriate research strategy should be developed to study this weed in more detail, and an awareness and prevention campaign be developed within country to help combat this weed in the early years of its invasion.
(This article was published in International Parthenium News, No. 5, January 2012.)