Effect of Alley Cropping on Crops and Arthropod Diversity in Duzce, Turkey

The influence of alley cropping practices on trees, agricultural crops and arthropod diversity was studied in Duzce, Turkey. Six replications of three crops, maize (Zea mays L. var. rugosa), beans (Phaseolus vulgaris L.) and zucchini (Cucurbita pepo L.), were planted in the alleyways between rows of hybrid poplar [Populus euramericana (Dode) Guinier] in a plantation setting. Control plots included a poplar plot without crops and the three crops planted in plots without trees near the plantation. Sweep netting, sticky traps, pitfall traps, and cloth shaking were used four times throughout a growing season to sample arthropods in the research area. Alley cropping practices had both negative and positive effects on crop yield and a significant negative effect on poplar growth. A total of 10 284 arthropod specimens (15 orders and 122 families) were collected, 118 families in the agroforestry plots, 57 families in the treeless plots and 44 families in the poplar control plot. Diversity indices did not differ among plots, except for the Shannon index, for all dates and sampling methods combined. Evenness indices and family richness measures did not differ significantly among plots, but significant differences were found among collection dates and sampling methods. The tree canopy had a greater arthropod diversity than the ground vegetation. Beneficial arthropods were found in significantly greater numbers in the agroforestry plots compared to the monocrop plots. This suggests that trees provided a more favourable habitat for beneficial arthropods than herbaceous plants. We conclude that agroforestry may contribute to increasing arthropod diversity compared with monocrops.