Ap. Kinzig et J. Harte, SELECTION OF MICROORGANISMS IN A SPATIALLY EXPLICIT ENVIRONMENT AND IMPLICATIONS FOR PLANT ACCESS TO NITROGEN, Journal of Ecology, 86(5), 1998, pp. 841-853
1 Evolution of a microbial nitrogen-uptake strategy that removes nitro
gen at less than the maximum potential rate creates soil environments
favourable for increased plant access to nitrogen. Plant productivity
is thus increased, and achievement of maximum microbial biomass is fac
ilitated through increased microbial access to plant-derived carbon. 2
Simulations show that micro-organisms exhibiting such a 'strategic' n
itrogen uptake will be competitively excluded by more voracious micro-
organisms in a homogeneous system, but can persist in a spatially expl
icit system. This persistence of less voracious micro-organisms contra
sts with the frequently held view that micro-organisms in soil systems
take up nitrogen at the maximum possible rate. 3 The selection of str
ategic or voracious microbial types in a spatially explicit environmen
t is sensitive to the frequency of plant and microbial disturbance, an
d to the rate of diffusion of inorganic nitrogen in the soil system. I
n particular, the strategic (less voracious) microbial types are favou
red under conditions of low plant disturbance, low to moderate diffusi
on of inorganic nitrogen, and moderate microbial disturbance. 4 When s
election favours strategic microbial types, plant access to nitrogen i
s increased. Plants may also evolve strategies in a spatially explicit
environment that will increase population densities of favourable, st
rategic microbial types.