a number of
hypotheses have been proposed to explain this paradox.
For example, N additions may have indirect effects
on microbial communities by altering plant community
composition and/or the amounts and types of plant C
inputs to soils, reducing microbial activity levels (Meier
& Bowman, 2008). Other hypotheses involve N-induced
shifts in microbial physiologies and/or microbial community
compositions that are directly associated with
increased soil N availability