How and why grasshopper community maturation rates are slowing on a North American tall grass prairie

Abstract

Invertebrate growth rates have been changing in the Anthropocene. We examine rates of seasonal maturation in a grasshopper community that has been declining annually greater than 2% a year over 34 years. As this grassland has experienced a 1°C increase in temperature, higher plant biomass and lower nutrient densities, the community is maturing more slowly. Community maturation had a nutritional component: declining in years/watersheds with lower plant nitrogen. The effects of fire frequency were consistent with effects of plant nitrogen. Principal components analysis also suggests associated changes in species composition—declines in the densities of grass feeders were associated with declines in community maturation rates. We conclude that slowed maturation rates—a trend counteracted by frequent burning—likely contribute to long-term decline of this dominant herbivore.