B) adding nitrifying bacteria to the soil
C) adding denitrifying bacteria to the soil
D) using ammonia instead of nitrate as a fertilizer
Use the following information to answer the question(s) below.
Abstract:
Increased radiative forcing is an inevitable part of global climate change, yet little is
known of its potential effects on the energy fluxes in natural ecosystems. To simulate
the conditions of global warming, we exposed peat monoliths (depth, 0.6 cm; surface
area, 2.1 m2) from a bog and fen in northern Minnesota, USA, to three infrared (IR)
loading (ambient, +45, and +90 W m-2) and three water table (-16, -20, and -29 cm in
bog and -1, -10 and -18 cm in fen) treatments, each replicated in three mesocosm plots.
Net radiation (Rn) and soil energy fluxes at the top, bottom, and sides of the mesocosms
were measured in 1999, five years after the treatments had begun. Soil heat flux (G)
increased proportionately with IR loading, comprising about 3%-8% of Rn. In the fen,
the effect of IR loading on G was modulated by water table depth, whereas in the bog, it
was not. Energy dissipation from the mesocosms occurred mainly via vertical exchange
with air, as well as the deeper soil layers through the bottom of the mesocosms, whereas
lateral fluxes were 10- to 20-fold smaller and independent of IR loading and water table
depth. The exchange with deeper soil layers was sensitive to water table depth, in
contrast to G, which responded primarily to IR loading. The qualitative responses in the
bog and fen were similar, but the fen displayed wider seasonal variations and greater
extremes in soil energy fluxes. The differences of G in the bog and fen are attributed to
differences in the reflectance in the long waveband as a function of vegetation type,
whereas the differences in soil heat storage may also depend on different soil properties
and different water table depth at comparable treatments. These data suggest that the
ecosystem-dependent controls over soil energy fluxes may provide an important
constraint on biotic response to climate change.
Copyright 2004 Springer-Verlag (A. Noormets et al. 2004. The effects of infrared
loading and water table on soil energy fluxes in northern peatlands. Ecosystems
7:573-582.)
The Noormets et al. study (2004) shows that there was an ecosystem-specific control
over soil energy fluxes, and this constrained the biotic response to climate change. How