Sampling design and data collection
A total of eight 50 × 50 m plots were randomly established in each of
three forest sites namely, edge, interior and deep-interior. Each forest
site had two randomly demarcated and independent sampling areas, each of
which contained four plots. The edge site was defined as 0-50 m from the
forest edge, while interior and deep-interior sites were 200 m and 400 m
from the forest edge, respectively. Variable penetration distances of
edge have been reported in previous studies. A lot of studies revealed
that edges can extend up to 100 m from the forest edge, while other
studies also detected edge effects up to 300 m (see Ofosu-Bamfo et al.,
2019). Thus, we set our two interior sites 100 m beyond each of the
aforementioned edge penetration distance limit, resulting in 200 m and
400 m distances from the forest edge.
We surveyed and identified all lianas with diameter (at 1.30 m from the
rooting base) ≥ 1 cm as well as trees (diameter at breast height ≥ 10
cm) that carried lianas in the plots. The minimum inter-plot distance in
the sampling areas was 150 m. Plant species were identified by a plant
taxonomist, and through the use of herbarium specimens and
identification guides (Hawthorne & Jongkind, 2006; Hawthorne, 1990).