Principles of terrestrial ecosystem ecology.pdf

C import
Volatile
emissions
Gross primary
production
Harvest
Net primary
production
respiration releases the minerals that support
NPP (Harte and Kinzig 1993). For these
reasons, NPP and heterotrophic respiration
tend to be closely matched in ecosystems at
steady state. At steady state, by definition, NEP
equals zero, regardless of carbon input or
climate. In fact, peat bogs, which are quite
unproductive, are the ecosystems with the
greatest long-term carbon storage, because the
anaerobic soil conditions characteristic of these
bogs restrict decomposition more strongly than
they restrict NPP.
Atmospheric inputs Atmospheric outputs
CO 2
CO 2
Plant litterfall,
mortality, and
exudation
Microbial
respiration
Fire
Plant
respiration
Soil organic matter
inputs and
microbial biomass
D Plant biomass D Soil organic matter
Net ecosystem production
Leaching loss
CO 2
Excretion
Animal
mortality
Leaching
Leaching
Net Ecosystem Production 141
Animal
consumption
Assimilation
D Animal biomass
Animal
respiration
Net secondary
production
Figure 6.8. Overview of the carbon fluxes of an ecosystem. The large box represents the ecosystem, which
exchanges carbon with the atmosphere, other ecosystems, and groundwater.
CH 4
CO 2
Leaching of dissolved organic carbon (DOC)
and dissolved inorganic carbon (DIC) to
groundwater and streams is a quantitatively
important avenue of carbon loss from some
ecosystems (Fig. 6.8). Groundwater is generally
supersaturated with respect to CO2 because of
the high CO 2 concentration in the soil atmosphere.
Some dissolved CO2 leaches out of the
ecosystem to groundwater and then moves to
streams and lakes, where the excess CO2 is
C export