Microbial Controls on Humification in Diverse Forest Systems.

Microbial metabolism is widely accepted as the driving force in humification processes; however, turnover models wholly overlook the importance of microbial biochemistry despite the fact that most plant residues likely pass through microbial biomass prior to conversion to carbon dioxide (CO2) and humic substances (Kogel-Knabner, 2002). This research investigates the importance of microbial biochemistry to carbon (C) dynamics and humification pathways in two climatically different forested ecosystems, Blodgett forest (BF), a temperate forest in the Sierra Nevada and Luquillo forest (LF), a tropical forest in Puerto Rico. These sites represent diverse ecosystems that are known to support substantially different microbial communities. The origin of microbial C (temperate vs. tropical-derived) has no strong correlation to the overall rate of decomposition in either temperate or tropical forest soils, differences observed between microbial groups demonstrates that the quality or biochemistry of microbial substrates may initially affect the rate of decomposition or turnover of microbial C in both temperate and tropical forest systems, but throughout later stages of humification the initial source or quality of microbial C becomes less important to the amount of C that is stabilized in these systems.