RATIONALE<P>

     Landscape variability in resource availability and rates of
ecological processes in grasslands can be as great as temporal
variation. In particular, tallgrass prairie in the highly dissected
Flint Hills of eastern Kansas is characterized by significant
spatial heterogeneity in the availability of water, nitrogen and
light (Schimel et al., 1991; Knapp et al., 1993). Much of this
heterogeneity is related to topographic position in the landscape.
Permanent east-west transects across elevational gradients were
established in 1989 in an annually burned and a long-term unburned
watershed on Konza Prairie to document spatial patterns in abiotic
and biotic variables. Each transect is ca. 300 m in length and has
11 permanently marked sampling locations. A long-term commitment to
this study will enable us to document both spatial and temporal
dynamics, and interactive effects of landscape position and
climatic variability on key ecological processes. Questions
addressed include:<P>

Does landscape position affect resource availability (water, N) and
plant response similarly in burned and unburned watersheds?<P>

How variable is NPP across topoedaphic gradients (spatially and
temporally)? Do drought (or wet) years amplify or modulate<P>
variability in NPP?

What are the effects of landscape position on above- and
belowground decomposition processes?<P>

How do patterns of soil N availability, plant uptake and N use
efficiency vary with landscape position and burning treatment? Does
allocation of C and N to microbial biomass, mineralizable C and N
pools and stable pools vary with landscape position?<P>

Do soil communities (invertebrates and mycorrhizal fungi) differ
with respect to landscape position?<P>

     We will sample seasonally and annually along these transects
and a termination date has not been set. At this time, resources do
not allow replication of the transects. As a result, short-term
replicated experiments will be designed and used when appropriate
to statistically test for fire effects (Knapp et al., 1993).
Variables to be measured include: NPP, soil moisture, plant C and
N, litter decomposition, microbial biomass, N availability,
mineralizable C and N pools, mycorrhizal fungi species, soil
nematodes and microarthropods.<P>

Schimel, D.S., T.G.F. Kittel, A.K. Knapp, T.R. Seastedt, W.J.
     Parton and V.B. Brown. 1991. Physiological interactions
     along resource gradients in a tallgrass prairie. Ecology
     72: 672-684.<br>
Knapp, A.K., J.T. Fahnestock, S.P. Hamburg, L.B. Statland,
     T.R. Seastedt and D.S. Schimel. 1993. Landscape patterns
     in soil-plant water relations and primary production in
     tallgrass prairie. Ecology 74: 549-560.<BR>