Rios (2026) Investigating edge effects on arthropod diversity ground beetle assemblages and pest predation by Pterostichus melanarius (Coleoptera Carabidae) in canola agroecosystems of Central Alberta Canada – Chapter 2 – Supplementary Appendix 2.1

To assess the relationship between sampling effort and observed values of richness and diversity, I wrote a custom script in R version 4.4.2 to calculate richness and Shannon diversity based on the number of squares (6.45 cm-2, manufacturer-printed) processed per card (code available in Supplementary Appendix 2.1). For this, I first processed 20 cards from one time point in their entirety, recording the occurrence of arthropods on a per-square-basis.

For each card, I then performed a series of permutations in which one to 70 random squares (i.e., the entire card) was progressively sampled, and richness and Shannon diversity calculated with ‘vegan’. This approach generated 50 estimates of richness and diversity per card and sampling effort level, which were then averaged for each level. Finally, I constructed rarefaction curves for these estimates averaging data from all 20 cards.