Data from: Testing rangeland health theory in the Northern Great Plains

• Correctly assessing whether rangeland ecosystem services are stable,
improving, or degrading is of global importance. Soil aggregate stability
(SAS) is widely used to infer rangeland health, partly because high SAS is
thought to reduce runoff by increasing infiltration. We studied the
sensitivity of SAS to grazing and other disturbances, the effects of SAS
on infiltration, and the utility of alternative indicators of infiltration
in the Northern Great Plains.• To test grazing effects on SAS, we compared
SAS between paired areas that were lightly to moderately grazed or
excluded from grazing for 6 years. Additionally, we compared SAS between
grazed and not-grazed plots of a two-year controlled grazing experiment
with moderate and severe grazing. Also, we applied herbicide, mowing, and
fungicide treatments to test SAS responses to disturbances more generally,
as well as effects of SAS and other factors on infiltration. To more
generally test for a SAS-infiltration relationship, we performed a
meta-analysis of our data combined with other data from the region. •
Grazing often reduced stability of small macroaggregates (0.25-1 mm) in
the controlled grazing experiment but not the paired grazing area
experiment. Grazing had no detectible effect on SAS of larger
macroaggregates (1-2 mm). Herbicide tended to reduce SAS, and mowing
sometimes increased SAS. Infiltration exhibited high plot-to-plot
variation and was not significantly affected by treatments. Variation in
infiltration was best explained by plant community composition variables
and was not explained by either SAS or other soil properties. Our
meta-analysis revealed no general SAS-infiltration relationship. •
Synthesis and applications. Our findings counter prevailing expectations
that SAS is consistently sensitive to rangeland disturbance(s) and a
leading indicator of soil water transport. Plant community composition
properties were better predictors of infiltration. Our findings support
theory that excessive grazing increases the prevalence of a grazing
tolerant species, which was associated with low levels of infiltration
irrespective of SAS.