3. RESULTS
A total of 19,053 beetle individuals were recorded across all sampling
sites during the study period, which represents 64 beetle families. The
rarefaction and extrapolation curves, adjusting for the number of
specimens collected in natural forests and plantation areas, clearly
revealed that beetle community composition in natural forests had a
higher overall cumulative diversity of families compared to plantations
(Figure 2). We also determined that the highest diversity was sampled at
site 8, 3, and 5 in natural forests respectively (Figure S1).
Beetle community composition did not appear to be dependent on any of
the variables tested, according to the PERMANOVA analysis (Table 2).
However, visual examination of NMDS indicated that the beetle families
collected differed between trapping methods (Figure S2), and that beetle
communities were largely overlapping between natural forests and
plantation areas (Figure 3).
The richness of beetle communities (in terms of the estimated number of
families per site) was found to be dependent on the trapping method
(P = 0.006) (Table 3), but was not influenced by the other three
variables of interest (landscape context, temperature, and
precipitation). In addition, there was also no significant effect of any
variable on beetle community diversity as estimated by Shannon and
Simpson indices (Table S2, S3).
There was a strongly significant effect of all tested variables, except
temperature, on the variation of beetle abundance across sites (Table
4). Specifically, the abundance of beetle communities was significantly
higher (ca. ×3 on average) in the natural forest compared to plantations
(P = 0.0014), differed between trapping methods (P = 0.0001), and was
positively associated with precipitation (P = 0.0146) (Figure 4). When
analyses were computed for each family separately, we highlighted a
similar pattern of higher abundances in the natural forest compared to
plantations; we also identified significant effects of temperature and
precipitation as well as trapping methods (Table S1).