Data set ID:
OBJECTIVE: The purpose of the study is to investigate how pulses of precipitation translate into
pulses of plant above ground net primary productivity (NPP) and how the small mammal community
responds to such changes also in relation to shrub gradient across the landscape. Particularly
we are interested in how the energy flows through the ecosystem in response to pulses of rain,
how the small mammal community partition resources (in terms of C3 (forbs and shrubs) and C4
(grasses) plants) and how the genetic structure of some species (i.e.: Dipodomys spp.) is
affected by their population dynamics.
1) Small mammal abundance should respond positively to precipitation and NPP.
2) On a temporal scale, the small mammal energy use should show parallel fluxes along the shrub
3) The small mammal community should consume C3 and C4 plants according to their availability (or
4) At low population density, dispersal should be limited and the genetic variance will be
distributed among populations rather than within (i.e., Fst will trend towards higher values).
After pulses of rain and NPP, population densities will be greater, dispersal prevalent, and
the genetic variance of populations will be distributed within populations (i.e., Fst will
approach zero) as dispersal homogenizes populations.
Variables include rodent species, sex, reproductive status, weight, and maturity status were recorded.
Digital voice recorders and data sheets
At each site, three rectangular trapping grids (300m X 100m, 16 X 6 traps, 20m apart) were
permanently marked in each of the three habitat types characterizing the ecotone (shrubland,
grassland, and the transition zone between them) where small mammal trapping took place.
Trapping occurred for 4 consecutive nights using Sherman-type live traps (one at each station)
baited with a seed mix. Traps were checked every morning and rodents were uniquely marked with
ear tags or individual colored numbers with permanent markers and released unharmed at the point
of capture. Color blue was used for the first night, Black on the second night and Red on the
third night. On the last night new individuals were not marked but recorded as new.
Preliminary treatment of data:
The 5 sites are located in JER Pastures 9, (12A & 4A), 15 and in CDRRC Pastures 3, 15.
GPS coordinates are available from Barbara Nolen.