SGS-LTER Long-term Seasonal Root Biomass on the Central Plains Experimental Range, Nunn, Colorado, USA 1985-2007, ARS Study Number 3

This data package was produced by researchers
working on the Shortgrass Steppe Long Term
Ecological Research (SGS-LTER) Project,
administered at Colorado State University.
Long-term datasets and background information
(proposals, reports, photographs, etc.) on the
SGS-LTER project are contained in a comprehensive
project collection within the Digital Collections
of Colorado
(http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429).
The data table and associated metadata document,
which is generated in Ecological Metadata
Language, may be available through other
repositories serving the ecological research
community and represent components of the larger
SGS-LTER project collection. The belowground system in arid and semiarid
regions can be of relatively greater importance
than in more mesic systems because plant
competition is most often for soil water rather
than for light in aboveground canopies.
Belowground plant biomass in the shortgrass steppe
represents approximately 80% of the total. These
data, entitled Long-Term Seasonal Root Biomass,
were obtained in section 21 of the Central Plains
Experimental Range from 1985-2008 in conjunction
with a 14C labeling experiment designed to test
isotope methods of estimating root production.
Paired plots for each of eight replicate 14C
labeled plots were established and cored on
average six times per year over 13 years (five
cores each plot each date as above). There were
two primary objectives for collecting these data,
1) to compare estimates of root production (or
belowground net primary production - BNPP)
obtained using the sequential coring of biomass
methods with various isotope, minirhizotron,
ingrowth, and other methods, and 2) to examine
long-term controls on the temporal dynamics of
root biomass. This shortgrass steppe LTER site is
the only place we are aware of that has compared
most methods of estimating BNPP, including
sequential coring, ingrowth cores, and ingrowth
donuts, 14C pulse-isotope dilution, 14C
pulse-isotope turnover, rhizotron windows, and
minirhizotron, and indirect methods including
nitrogen budget, carbon flux, simulation carbon
flow model, and regression model. All production
methods are compared in Milchunas (2009), and more
detailed comparisons among particular methods can
be found in Milchunas and Lauenroth (1992, 2001),
and Milchunas et al. (2005a, and 2005b). Results
and conclusions concerning root biomass dynamics
and relationships with precipitation, season, and
aboveground biomass are reported primarily in
Milchunas and Lauenroth (2001). If you are
interested in using these data they are
downloadable from the SGS website, however we
encourage you to seek advice from the researchers
on the SGS project before you apply this dataset.
Milchunas D. G., and W. K. Lauenroth. 1992. Carbon
dynamics and estimates of primary production by
harvest, C14 dilution, and C14 turnover. Ecology
73:593-607. Milchunas, D. G., and W. K. Lauenroth.
2001. Belowground primary production by carbon
isotope decay and long-term root biomass dynamics.
Ecosystems 4:139-150. Milchunas, D. G., J. A.
Morgan, A. R. Mosier, and D. LeCain. 2005a. Root
dynamics and demography in shortgrass steppe under
elevated CO2, and comments on minirhizotron
methodology. Global Change Biology 11:1837-1855.
Milchunas, D. G., A. R. Mosier, J. A. Morgan, D.
LeCain, J. Y. King, and J. A. Nelson. 2005b. Root
production and tissue quality in a shortgrass
steppe exposed to elevated CO2: Using a new
ingrowth method. Plant and Soil 268:111-122.
Milchunas, D. G. 2009. Estimating root production:
comparison of 11 methods in shortgrass steppe and
review of biases. Ecosystems 12:1381-1402. Additional information and referenced materials can be found: http://hdl.handle.net/10217/85665.