2.3.3 Correlates of habitat factors and ant assemblage
composition
We conducted constrained ordinations to understand how microclimate (air
temperature relative humidity, and PPFD) and microhabitat structure
(total leaf area) affect ant assemblage composition. We first conducted
Detrended Correspondence Analysis (DCA) using the decoranafunction in the vegan package and found maximum axis length greater than
4 (range: 3.91-6.96) indicating that Canonical Correspondence Analysis
(CCA) constrained ordinations that assume unimodal responses of species
to environmental gradients were appropriate. We then checked the
collinearity among all explanatory variables using vif.ccafunction to reduce redundancy in the model. No strong collinearity
(VIF<10) was detected between microclimate and microhabitat
variables, and so all predictors were included in the Canonical
Correspondence Analysis (CCA). We then conducted CCA ordinations usingcca function in the vegan package with all explanatory variables
(air temperature, relative humidity, and PPFD). We conducted backward
model selection using the ordistep function in the vegan package
to identify the most significant variables affecting the assemblage
composition based on permutation tests using 1000 permutations (Blanchet
et al. 2008). As the model selection process for CCA analysis requires
samples with all environmental factors available, only 48 out of total
61 ant assemblages that had all environmental information available were
included for this analysis.
Results