Indonesian

Abstract

Gunawan H, Heriyanto NM, Subiandono E, Mas’ud AF, Krisnawati H. 2015. Invasion of exotic species on degraded land after eruption in Mount Merapi National Park. Pros Sem Nas Masy Biodiv Indon 1: 1027-1033. After the huge eruption of Merapi mountain in October-November, 2010, the forest ecosystem of Mount Merapi National Park was degraded heavily, which covered almost 76,87% of 6.145.05 Ha area. Around 766.67 ha or 12.48% of the degraded area became a desert of volcanic sand without vegetation at all. However, fertile soil combined with humid climate has changed the degraded land scenario rapidly through recolonization of pioneer species due to natural succession process. Unfortunately, an alien species named Acacia decurrens has invaded the bare land unpredictably. The invasion of A. decurrens is supposed to disturb the natural ecosystem of mountainous forest conserved by the national park of Mount Merapi. The objectives of this research were to study the growth and behavior of alien species in natural succession process on degraded land in Mount Merapi National Park. A combination of line and multi-square plots method was applied for vegetation analysis. The research found 29 species of tree seedlings that colonized the bare land where ten species were not indigenous in Mount Merapi. The most invasive among the ten exotic species was A. decurrens which had the highest important value index (32.62). The speed of invasion of A. decurrens was very high. Within the eight months after the eruption in July 2011, this species covered the bare land with 3000 plants per hectare in Cangkringan Resort and 8.214 plants per hectare in Kemalang Resort. Eighteen months after the eruption in March 2012, the density of A. decurrens in Cangkringan Resort increased to 7000 trees per hectare and in Kemalang Resort became 43.333 trees per hectare. As an unwanted species in a conservation area, the presence of A. decurrens must be controlled and gradually replaced by indigenous species through a restoration program