Does non-native black locust afforestation affect soil biodiversity at the regional scale? Case study of soil macroinvertebrates across the Chinese Loess Plateau

Abstract

Land-use changes have a profound impact on species diversity and distribution. Although soil fauna contribute substantially to global biodiversity and ecosystem functioning, the responses of soil fauna to land-use changes at the regional scale remain poorly understood. Non-native Robinia pseudoacacia (black locust, BL) has been widely planted on abandoned cropland to control soil erosion on the Chinese Loess Plateau (CLP). Here, we investigated the effects of BL plantations (<15 years, 15–25 years, >25 years) on the abundance, richness and community composition of soil macroinvertebrates at six sites along a 500-km transect across the CLP. Overall, the mean abundance and richness of macroinvertebrates were greater in the BL plots than in the control plots, regardless of the plantation age. These differences were mainly attributed to the changes in the abundance and richness of predators and phytophages but not of detritivores and omnivores. We also found that the abundance and richness of overall macroinvertebrates decreased with latitude in the BL plots, while no latitudinal trend was found in the control plots, which led to a decrease in the afforestation-induced positive effect with latitude. Additionally, the community composition of macroinvertebrates was similar between the control and BL plots but significantly varied with latitude, which was explained by climate factors and geographic distance. The results indicated that the positive effects of BL afforestation on macroinvertebrate diversity depend on functional groups and the community composition at a large spatial scale was shaped by climate factors and geographic distance rather than BL afforestation. If afforestation has biodiversity objectives, then BL afforestation is more suitable in the south than in the north of the CLP because of the decrease in afforestation-induced positive effects with latitude.