2011 - Cooperative Institute for Research in Environmental Sciences ...

PHOTO BY C. RHOADES, AUGUST 2006.
Spatially heterogeneous progression of mountain pine beetle infestation is the cause of the “red hand of death” pattern in a small watershed of the U.S. Forest Service
Fraser Experimental Forest, Colo., as bark beetles initially infest large, mature lodgepole pine and avoid smaller trees regenerating in previously logged areas.
The Center also continues to work on comparisons of
food web structure in lakes that contain fish and lakes that
lack fish. The lakes under study are in Rocky Mountain
National Park, where stocking is currently prohibited.
This is one of the few places where multiple waterbodies
of similar morphometry and size can be compared on the
basis of presence or absence of fish. CIRES Ph.D. student
Thomas Detmer is leading the research.
The Center for Limnology also continues its studies
of metabolism of the South Platte River downstream
of Denver. Large changes in chemistry of the river are
expected as new treatment facilities are constructed for
removal of nitrogen and phosphorus, in compliance with
new nutrient standards adopted by the State of Colorado.
The interplay between nitrogen and organic matter will
be especially interesting. Denitrifying microbes, which
use nitrate as an electron acceptor, require abundant labile
organic matter to grow. They also require anoxic conditions,
which they find now below the sediment surface. A
change in the balance between labile organic matter and
nitrate in the future could drastically affect the denitrifying
capabilities of the river, which are beneficial in
reducing high concentrations of nitrate that originate from
effluent and from nonpoint sources including agriculture.
Modeling and experiments are underway to determine the
probable effects of change in wastewater quality.
Figure 1: Examples of nitrate release from watersheds in response to
several kinds of canopy disturbance, including tree mortality caused by
beetles.
CIRES Annual Report 2011 61