Print Edition - 2017-09-27  |  The Collegian

The forest killer

Sep 27, 2017-

The first National Park of Nepal, Chitwan National Park (CNP) was established in 1973, and granted the status of World heritage site in 1984. CNP, 932 sq km in area, is home/habitat to important animals such as one-horned rhinoceros, Asiatic elephant, Bengal tiger, and Giant Horn-bill among others. Invasion by one dangerous and alien element can threaten the whole fauna of the area. 

One of the biggest threat to CNP is the encroachment of wildlife habitat which is followed by the dominance of invasive species in and around the national park. Globally, almost 20 percent of vertebrates thought to be in danger of extinction are threatened in some way by invasive species like Mikenia.

The most common invasive species of CNP is Mikenia Micrantha, also locally known as Banmara or Barahmase—the forest killer. This species is an exceptionally fast growing perennial vine also known as “mile a minute”. Although it originated from South America, it was first seen in the park in 1992 in the aftermath of a flood brought on by Rapti river.

In the present scenario almost 44 percent of the land of CNP is affected by Mikenia and 15 percent of this area has a very high infestation. It has dominated the park especially across the Rapti river. Recorded as one of the 100 worst alien species and second most serious weed in South Asia, Mikenia has adversely caused social instability, economic hardship, and impact on food security in the park and buffer-zone areas. The subtropical mixed hardwood forests are mostly affected whereas wetlands, tall and short grasslands and Sal forests have comparatively lower effects. 

Herbivores like rhinoceros and various ungulate species are compelled to either move to the inner core areas for the fulfillment of their habitat requirements or adopt Mikenia Micrantha as their new food to fulfill the dietary requirement. If the animals shift their settlement towards the core areas of the park, it will increase the pressure on the limited available resources thereby creating an inter/intra specific competition.

The effect of invasive species on the rural communities of the buffer-zone area is quite complex. The communities of the buffer-zone are directly or indirectly dependent on the forest resources. The increased population has already created pressure on the natural resources and that limited resource is under strain due to Mikenia. People are compelled to spend more time and energy in searching for fodder and fuel wood than before. This has also severely affected the tourism industry. 

Although research, monitoring, and management of invasive species have not been prioritised in Nepal, there are several temporary methods through which we can manage the growth of Banmara. The easiest and cheapest method to get rid of it is by manually pulling the young and old plants with hand or mechanical support. The local village dwellers have used Mikenia as manure, fodder, medicine and briquettes. Researchers show that planting of sweet potato (perennial vine) and Cuscutacampestris(parasite vine) is a biological control agent to suppress its growth. Some species are even sensitive to many herbicide such as 2,4-D glyphosate before flowering. In the present context, very few initiations have been conducted by various institutions to control these species. The activities conducted by them are not well coordinated or documented. The National Trust for Nature Conservation (NTNC) has been contributing a lot to minimise the effect of these plants. An International Conference on Invasive/alien species management was conducted by NTNC on March 2014. The conference highlighted urgent strategies that need to be adopted for the prevention. We need to formulate stronger national policy and scientific management techniques to control the invasion and spread of Banmara to preserve the park in its wilderness.

 

- Apsana Kafle

Kafle is a Bsc Forestry student at the Institute of Forestry, Pokhara

Published: 27-09-2017 09:48

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