Seasonal succession of pollinator floral resources in four types of grasslands

Abstract

Pollinators are declining globally, and this decline in ecosystem services threatens the stability of agricultural and natural systems. Pollinators depend on a diversity of floral resources that are primarily found in uncultivated areas of agro-ecosystems such as grasslands. Seasonal succession (the seasonal changes that occur in community composition and structure) of floral resources is an essential consideration for pollinator conservation within agro-ecosystems. Different types of grasslands common within agricultural landscapes could be expected to differ in their seasonal succession of floral resources. Here we investigated how different types of grasslands important for pollinator conservation in the tallgrass prairie ecoregion (remnant prairies, reconstructed prairies, conservation grazed cattle pastures, and old fields) differ in their seasonal succession of floral resources by sampling the plant community every two weeks from 3 May through 4 October 2013. We found remnant prairies had greater richness of inflorescences when summed over the growing season, and that remnants were least similar to the other grassland types in terms of composition. Reconstructed prairies had high richness of inflorescences and exhibited the most similarity in composition to remnant prairies only during the middle of the growing season. Conservation grazed cattle pastures had more periods where turnover in composition from one survey to the next was low, indicated by the coefficient of variation in turnover throughout the season. Old fields had the lowest richness of inflorescences and were significantly different from reconstructed and remnant prairies.