Canopy openness in gaps determines the influence of herbaceous climbers and insect folivory on the survival of a tropical pioneer tree,Neoboutonia macrocalyx Pax

Gaps created 10 years ago by clearing of conifer plantations in Kibale National Park, Uganda, still experience very little tree regeneration. We studied the arrested succession by examining the survival of Neoboutonia macrocalyx Pax in different sized canopy gaps. We examined whether Neoboutonia seedlings can survive in gaps, which the tree rarely colonizes naturally and whether survival is limited by the size of the canopy opening, herbaceous climbers or insect folivory. A total of 384 seedlings were planted in 24 gaps, and survival was monitored for 19 months. Survival was dependent on canopy openness, being lowest in small gaps and highest in large gaps. We found a significant negative relationship between survival and folivory and a positive relationship between survival and climber infestation. Because 53% of the seedlings survived, regeneration could be limited by seed dispersal, rather than high seedling mortality. However, considering its high survival rate in arrested succession gaps, Neoboutonia seems to have good potential for forest restoration.