Liana community structure
There were more liana species in edge habitat than interior habitat, which in turn had more species than deep-interior site in the Asenanyo Forest Reserve (Table 1). Both the rarefaction and extrapolation curves attested to this observation (Figure 1a). The rarefaction curves did not reach asymptote, showing there could be more undetected species in the forest sites. The species in edge, interior and deep-interior sites belonged to 28 genera and 15 families, 26 genera and 16 families, and 24 genera and 12 families, respectively. Edge and interior sites had similar Shannon diversity index (P = 0.691; H’ = 2.93 and 2.91, respectively), while each of them supported significantly higher Shannon diversity index than deep-interior site (H’ = 2.74) (P = 0.004 and 0.010, respectively). Species evenness (E) was similar among all the forest sites in the Asenanyo Forest Reserve (P > 0.05; edge: E = 0.48, interior: E = 0.51, deep-interior: E = 0.53).
Within the Suhuma Forest Reserve, liana species richness was comparable among the three forest sites (Table 1). The identified liana species belonged to 29 genera and 15 families in edge site, 27 genera and 13 families in interior site, and 27 genera and 16 family in deep-interior site. The rarefaction and extrapolation curves of the forest sites depicted a similar trend, with the curves showing that there could be more undetected species in the forest sites (Figure 1b). Shannon diversity index in edge site (H’= 2.99) did not vary from that in interior site (H’ = 3.01) (P = 0.723). However, due to significantly higher species evenness in deep-interior site (P < 0.05; deep-interior: E = 0.59, edge: E = 0.45, interior: E = 0.50), it supported significantly higher Shannon diversity index (H’ = 3.20) than edge (P = 0.004) and interior (P = 0.027) sites.
The five most abundant liana species in edge and interior sites of the Asenanyo Forest Reserve were Millettia chrysophylla ,Salacia elegans , Griffonia simplicifolia , Alafia barteri and Motandra guineensis (Table 1). They contributed 54.5 and 54.3 % of total liana abundance in edge and interior sites, respectively. The 10 most abundant species in these sites contributed 74.9 and 74.8 % of the liana stems in edge and interior sites, respectively. All the above mentioned species also constituted the five most abundant species in interior site. Four of the above mentioned species namely, M . chrysophylla , G .simplicifolia , A . barteri , and S .elegans , together with Strophanthus preussii were the five most abundant species in deep-interior site, forming 58.3 % of the stems in this site. The 10 most abundant species in deep-interior site constituted 80.6 % of the total stems in the site.
In the Suhuma Forest Reserve, M . chrysophylla , G .simplicifolia , M . guineensis , Calycobolusafricanus and A . barteri were the five most abundant species in edge site, constituting 54.8 % of liana stems in the site (Table 1). The stems of the 10 most abundant species were 72.9 % of the liana abundance in edge site. In interior site, the five most abundant species included four of the above mentioned species in edge site (i.e., M . chrysophylla , G .simplicifolia , C . africanus , M .guineensis ) and Acacia pentagona . The abundance of these five species was 52.3 % of the total abundance in interior site. With regard to the 10 most abundant species, they contributed 75.3 % of the liana abundance in the site. M . chrysophylla , A .pentagona , G . simplicifolia , C .africanus , and A . barteri formed the five most abundant species in deep-interior site, by contributing 41.3 % of the liana stems in deep-interior site. In the same forest site, the 10 most abundant species contributed 65.8 % of the total liana stems in the site.
Liana abundance differed significantly between edge and deep-interior sites of the Asenanyo (F = 3.84; P = 0.041) and Suhuma (F = 6.05; P = 0.010) Forest Reserves (Table 1). Nonetheless, there were no significant differences in liana abundance among the other forest sites. In both forest reserves, there was no significant effect of sampling site on liana abundance (Asenanyo: F = 0.091, P = 0.964; Suhuma: F = 2.16, 0.128). MEI in the Asenanyo Forest Reserve ranged from -1 to 0.92 (Table 1). More species experienced positive MEI on their abundance than those that had negative MEI on their abundance. Caesalpinia cucullataand Combretum acutum were the only species that experienced very strong MEI in the Asenanyo Forest Reserve. Paullinia pinnata was the only species with strong MEI on its abundance. The rest of the species recorded moderate, weak, and very weak MEI on their abundance. On the contrary, A . pentagona had no MEI on its abundance. In Suhuma Forest Reserve the MEI on liana species abundance ranged from -0.43 to 0.45 (Table 1). Liana species abundance experienced both positive and negative MEI, with the majority of the species experiencing positive MEI. Nevertheless, there was no MEI on the abundance ofStrophanthus sarmentosus in the Suhuma Forest Reserve. There was moderate MEI on the abundance of Manniophyton fulvum andNeuropeltis prevosteoides , while the MEI on the abundance of the remaining species was either weak or very weak.