Year of Publication

2012

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture

Department

Plant and Soil Science

First Advisor

Dr. Rebecca McCulley

Abstract

Climate change is likely to alter plant species composition and interactions between plants and soil microbes that together dictate the quantity and quality of forage produced in pastures, the base of animal production in central Kentucky. This study assessed the seasonal dynamics of soil microbes and their response to increased temperature (+3oC) and growing season precipitation (+30% of the mean annual). Total soil microbial biomass, community composition, enzyme activities, potential carbon mineralization, and catabolic responses to selected substrates were measured seasonally in the different climate treatments. In this system, seasonal variability was a dominant driving factor for all the soil microbial characteristics that I investigated. Summer maxima and winter minima were identified in the active microbial biomass, while soil microbial community structure differed between each season. Extracellular enzyme activities were generally highest in either the spring or summer, while seasonal patterns for each substrate were unique across catabolic response profiles. Climate treatments produced few significant main or interactive effects on the soil microbial biomass and function. This resiliency, coupled with evidence of functional redundancy, suggests that central Kentucky pasture ecosystems may be well-equipped to handle future environmental stress associated with climate change and to maintain critical ecosystem services.