Effects of Burning on Populations of Three Earthworm Species in Tall Grass Prairie.

Burning can cause increased plant production and warmer and drier soil on burned plots, which could have opposite effects on earthworm populations. To determine how earthworms respond to changes in these factors, I sampled populations on plots of prairie subjected to the following eight treatments: irrigated and unirrigated spring burned, fall burned, mulched, and control. I also measured soil physical characteristics, soil climate, soil nutrients, soil organic matter, litter, and st and ing crop. To allow interpretation of soil climate data, I conducted laboratory experiments on the tolerances of the earthworms for moisture and temperature levels. Populations on five different soil types were sampled also, as well as the other quantities measured on the plots. The study site was the Konza Prairie Research Natural Area near Manhattan, Kansas. Biomass of Diplocardia smithii and D. verrucosa increased on burned plots. D. smithii did not respond to irrigation, while D. verrucosa did. Aporrectodea turgida declined on burned plots and was more abundant on irrigated plots. The Diplocardias were more tolerant of high temperatures and low soil moisture availability than A. turgida, suggesting that this is the primary reason for the difference in response to burning. In contrast to other studies, soil organic matter increased on burned plots, and there was no difference between st and ing crop on fall and spring burned plots. The increased organic matter is the most likely reason for increased Diplocardia biomass on burned plots. A survey of five soil types also showed that the soils with the highest organic matter levels had the highest Diplocardia biomass. A. turgida was not present in all soils, so comparisons cannot be made. Another species, Octolasion cyaneum, was most abundant in the deeper soils. A. turgida appears to be exp and ing its range on the experimental area, in spite of temperature limitations. In all, nine species of worms were found on KPRNA, two of which are undescribed Diplocardia. The other species are D. prosenteris, D. singularis, D. smithii, D. verrucosa, Aporrectodea turgida, Octolasion cyaneum, and O. tyrtaeum.Ph.D.EcologyUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/159399/1/8314299.pd