The U.S. Department of Agriculture-Natural
Resources Conservation Service has recommended domestic
cattle grazing exclusion from riparian corridors for
decades. This recommendation was based on a belief that
domestic cattle grazing would typically destroy stream bank
vegetation and in-channel habitat. Continuous grazing (CG)
has caused adverse environmental damage, but along cohesive-
sediment stream banks of disturbed catchments in
southeastern Minnesota, short-duration grazing (SDG), a
rotational grazing system, may offer a better riparian management
practice than CG. Over 30 physical and biological
metrics were gathered at 26 sites to evaluate differences
between SDG, CG, and nongrazed sites (NG). Ordinations
produced with nonmetric multidimensional scaling (NMS)
indicated a gradient with a benthic macroinvertebrate index
of biotic integrity (IBI) and riparian site management; low
IBI scores associated with CG sites and higher IBI scores
associated with NG sites. Nongrazed sites were associated
with reduced soil compaction and higher bank stability, as
measured by the Pfankuch stability index; whereas CG sites
were associated with increased soil compaction and lower
bank stability, SDG sites were intermediate. Bedrock geology
influenced NMS results: sites with carbonate derived
cobble were associated with more stable channels and higher
IBI scores. Though current riparian grazing practices in
southeastern Minnesota present pollution problems, short
duration grazing could reduce sediment pollution if managed
in an environmentally sustainable fashion that considers
stream channel response.
Magner, Joseph, A.; Vondracek, Bruce; Brooks, Kenneth, N..
Grazed Riparian Management and Stream Channel Response in Southeastern Minnesota (USA) Streams.
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