Status of Mikania micrantha invasion in the rhino habitat of Chitwan National Park, Nepal.
Mikania micarantha (Mikania) is one of the world's 100 worst weeds and the primary invasive species in Chitwan National Park (CNP), Nepal. Following a Mikania survey in 2008, an additional survey was carried out in 2011 as part of greater one-horned rhinoceros (rhino) censuses to measure the extent of change of Mikania invasion in major rhino habitats in CNP. 2008 survey protocols were adopted: a plot including a half-circle of 50 m radius in front of a researcher was surveyed from elephant back for the ocular estimation of Mikania cover. Mikania coverage was quantified in the scales of 0, 1 and 2 where 0 - Mikania absent, 1 - Mikania present but less than 50% coverage and 2 - Mikania covering more than 50% of the plot area. Mikania was found present (1 and 2 combined) in 43.3% (n=3073) of the plots in 2011 and this was approximately the same as of 2008. In 2011, as in 2008, the preferred rhino habitats - wetland, tall grassland, riverine forest - were found to have higher level of Mikania invasion than other habitats. In between the three years of the assessment percentage of the plots in category 2 (more than half of plots covered by Mikania) has increased by 3.45% from 14.50% in 2008 to 17.95% in 2011. Overall, Mikania has not spread out in new areas but intensified where it was already present. Thus there is still the threat of Mikania high infestation on the area where it is present.