Effects of land-use and fungicide formulations on ecosystem function in playas and adjacent native grasslands and croplands.

摘要

Soil fungi contribute many ecosystem services, especially carbon sequestration. They are vulnerable to agriculture practices, such as tilling. The Southern High Plains (SHP) is an intensely cultivated area, with a high number of playa wetlands dispersed throughout cropland and native grassland. Native grasslands and playa wetlands have a high potential for carbon storage but also have a high potential for exposure to fungicides through spray drift and run-off. The increased use of fungicides in the past decade and their non-selective modes of action have become a concern, particularly the possible effect on non-target soil fungi. Therefore, the effect of land-use change and fungicides to non-target fungi was tested through fungal biomass and soil respiration studies. Soil from six grassland playas and six cropland playas, as well as soil from their adjacent uplands were exposed to four concentrations of two of the most popular fungicides, Headline® and Quilt ®. Fungal biomass was measured at two time points (6 and 15 days after treatment) using ergosterol analyses, involving a liquid-to-liquid extraction using diochloromethane and further analyzed using a high-performance liquid chromatographer. Soil respiration was measured with an alkaline trap method using air-tight jars and sodium hydroxide to capture carbon dioxide output for 14 days.;Ergosterol analyses indicated no effect of Headline® or Quilt® at any concentration. Additionally, neither fungicide demonstrated any concentration effect in soil respiration analysis. However, grassland wetlands had a higher amount of ergosterol at both measurements. In uplands, grasslands had a higher amount of ergosterol on day 6 following Headline treatment®. The soil respiration studies showed similar results; grasslands had a higher cumulative carbon dioxide output for both wetlands and uplands. I recommend that grassland soils, both uplands and wetlands, be conserved from further alterations. Higher amounts of fungal biomass and carbon dioxide indicate a high amount of productivity and carbon cycling; grasslands are known to sequester a higher amount of carbon. Thus, their conservation should be a high priority as the threat of global warming continues to increase.