The effects of farmland shelterbelts on surface arthropod distribution: A case study in Changtu County, China

Improving farmland biodiversity is important for ecological agriculture. To explore how well farmland shelterbelts protect biodiversity, eight farmland shelterbelt units (unit=one field parcel; shelterbelt types:complete, incomplete, or extinct) in Jinjia Town, Changtu County, Liaoning Province, China were selected, and the surface arthropod distribution in adjacent farmlands was investigated using pitfall traps. Surface arthropods were sampled at 0, 50, 100, 150, and 200 m from the shelterbelt, and the shelterbelt vegetation characteristics were recorded. Analysis of variance and community ordination were used to analyze how the shelterbelt type, distance gradients, and shelterbelt vegetation structure affected the surface arthropod distribution. The results showed that the surface arthropod abundance was significantly higher in fields adjacent to complete and incomplete shelterbelts. The shelterbelt type had no significant effect on diversity; however, the surface arthropod community composition on the farmland adjacent to complete and incomplete shelterbelts differed from the extinct shelterbelts. The abundance gradient variation was significant in fields adjacent to complete and incomplete shelterbelts, demonstrating a low to high variation trend with away from shelterbelts. In all units, the diversity decreased as the distance toward the edge increased, and a significant edge effect was observed. Redundancy analysis (RDA) and Monte Carlo tests showed that the herb layer species abundance and the shelterbelt tree coverage were the primary factors affecting arthropod community distributions, accounting for 35.4% of the total surface arthropod population variation. Arthropod responses to the shelterbelt vegetation community significantly differed based on the species, carabids, and spiders present. The primary natural enemy of the local agricultural landscape was closely related to the shelterbelt vegetation structure; the carabid species diversity was positively associated with herb layer abundance, and the spider family diversity was positively associated with tree coverage. Farmland shelterbelts (a non-cropped habitat) significantly increased the number of surface arthropods in adjacent fields but did not affect species diversity. The herb layer abundance and shelterbelt tree coverage had a positive effect on natural enemy diversity (e.g., carabids and spiders). Strengthening agricultural landscape woodlands, such as increasing upper tree coverage and understory vegetation, improves the habitat quality and conserves farmland biodiversity, thereby promoting sustainable agriculture.