The Effects of CO2 and Temperature on the Soil Microbial Carbon and Nitrogen of Urban and Rural Forests

Abstract

This study investigated and compared the effects of elevated temperature and elevated CO2 on the microbial biomass carbon (MBC) and nitrogen (MBN) of urban and rural forest soils. Soils analyzed from Baltimore Long-Term Ecological Research forests in June and October, 2014 had greater MBC and MBN quantities in rural than urban forests. A controlled environmental chamber study was conducted where June-collected soils were planted with hybrid poplars and exposed to ambient and elevated temperature and CO2 levels. After exposure for 49 days, MBC and MBN quantities were again greater in rural than urban soils. Soil MBC was greater under elevated than ambient CO2, while soil MBN was greater under elevated than ambient CO2 and temperature. Results suggest that if temperature and CO2 levels increase in the Baltimore area as predicted, microbial C and N pools in the studied forests will increase, and will remain greater in rural than urban soils.