Forest fragmentation drives liana community structure but not the patterns of liana–tree interaction network in two forest ecosystems in Ghana

Abstract

AbstractWe assessed fragmentation impact on liana community structure and patterns of liana–tree interaction network structure, and edge effects on liana community structure in a rainforest and a moist semi‐deciduous (MSD) forest in Ghana. In each forest, we randomly established 30 20 × 20 m2 plots at varied distances (0–20 m, 20–40 m, 40–60 m, 60–80 m, 80–100 m) from forest edge to interior in fragmented and intact sites. Lianas with diameter at 1.30 m from rooting base ≥1 cm and their host trees (diameter at breast height ≥ 5 cm) were identified and counted. Our findings revealed that fragmentation caused an increase in liana diversity in the rainforest, but not in the MSD. Fragmentation also resulted in shifts in species composition in both forests, and together with edge effects increased liana abundance in both forest ecosystems. Liana–tree networks in the two forest ecosystems were less nested and connected, but more modular and specialized than their corresponding null models irrespective of fragmentation. Some species of lianas (rainforest fragment/intact: 0.80/0.76%; MSD fragment/intact: 0.47/0.38%) and trees (rainforest fragment/intact: 0.65/0.35%; MSD fragment/intact: 0.54/0.36%) exhibited higher specialization than their null models. Topologically, most lianas in fragmented and intact sites of the forests played peripheral/specialist roles, whereas a few species exhibited structural importance in the form of connectors, network hubs and module hubs. The structural important species in fragmented sites did not also occur in intact sites, suggesting that fragmentation might have influenced topological roles of the species in fragmented sites.