Effect of three species of climber on the performance of Ceiba pentandra seedlings in gaps in a tropical forest in Ghana

Abstract

The proliferation of climbers can have deleterious effects on tree regeneration, especially in forest canopy gaps where climbers increase in abundance. In response to the colonization by climbers, the supporting tree can suffer a reduction in growth and its allometric relationships may be modified. We evaluated the effects of three species of climber on the performance of the pioneer tree Ceiba pentandra in a moist semi-deciduous tropical forest in Ghana. In each of three gaps, four plots were set up, each with eight Ceiba seedlings paired with a single plant of one of three climber species, planted within 5–10 cm of the tree seedling, plus a control (no climber). The climber species were: Centrosema pubescens, a nitrogen-fixing woody climber; Combretum racemosum, a woody climber and Dioscorea praehensilis, an herbaceous climber. After 12 mo, Centrosema and Combretum had about four to five times more biomass than Ceiba seedlings. There was no effect of climber competition on Ceiba biomass growth, and no relationship between climber biomass and Ceiba growth rate. Individual climber species, however, had other effects: Combretum caused a significant reduction in the height and diameter growth of Ceiba, whilst competition with Centrosema was associated with significant reduction in the crown area and increase in internode length in Ceiba. The results indicate that even very different climber species appear to cause negative effects on trees during regeneration.