Intensive grazing enhances grasshopper fitness and abundance in a meadow steppe

Abstract

Grazing management plays an important role in grassland conservation. Given that grasshoppers are key components in the grassland food web, various studies have been conducted to investigate the effects of grazing by large herbivores on grasshoppers at population and community levels. However, grazing effects on grasshopper fitness and abundance remain poorly understood. Here, using a field experiment in a meadow steppe, we examined the effects of sheep grazing, with different intensities, on grasshopper (Euchorthippus unicolor) fitness and abundance. Results showed that female grasshopper’s survival rate, mean survival time, and egg production were positively associated with increasing grazing intensities. The positive relationships are likely due to changes in plant nitrogen content and microhabitat induced by large herbivore grazing activities for grasshoppers. Moreover, there were strong positive associations between the fitness and abundance of female grasshoppers, and between female and total grasshopper abundance, which are responsible for an increase in overall grasshopper abundance. These findings improve our understanding about the role of grasshopper fitness in explaining their abundance in response to grazing management. Our study also suggests that measuring grasshopper fitness should be considered for species conservation in management practices of moderate grazing.