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Below are descriptions of current research projects of the Kolb Ecophysiology Lab
 | Insects as ecological indicators for southwestern ponderosa pine forests
NAU PIs Wagner, Bailey, Hart, and Kolb have been funded
recently by the USDA National Research Initiative Competitive Grants Program
to study how thinning and prescribed burning affects a range of ecosystem
characteristics in southwestern ponderosa pine forests. The following
characteristics will be compared in 2003 and 2004 among five stand types (unmanaged,
thinned, wildfire burned, thinned + prescribed burned, old-growth restored):
plant biodiversity, net primary productivity, vegetation structure, tree growth
and water stress, bark beetle populations, ant populations, and ground beetle
populations. We hypothesize that insect diversity and abundance can
be used as indicators of selected ecosystem characteristics, and
that many of these ecosystem characteristics are sensitive to forest management.
M.S. student Greg Zausen is using portions of this project for
his M.S. thesis.
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| Variation in tree radial growth response to drought among environments and species
M.S. student Henry Adams (hda2@dana.ucc.nau.edu)
is using tree rings to compare tree growth responses to historic drought events
among different tree species in several forest types and different forest
types and elevations for the same tree species. His work focuses on
pine-oak and mixed conifer forests that occur from elevations of 6,000 feet
to 11, 500 feet on the Colorado Plateau and San Francisco Peaks in northern
Arizona. The purpose of this research is to better understand how severe
droughts affect tree growth and species composition in forests. This
research is funded by the NAU School of Forestry Mission Research Program
and the McIntire Stennis Program.
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| Effects of restoration thinning on ponderosa pine forest water use
M.S. Student Kevin Simonin (kas79@dana.ucc.nau.edu)
is comparing forest stand and individual tree water use using sapflow techniques
between heavily thinned ponderosa pine stands and unthinned stands to better
understand effects of restoration thinning on site water balance. His
study sites are an old-growth stand at the Gus Pearson Natural Area, and a
younger stand at the NAU Centennial Forest. George Koch and Mario Montes-Helu
(NAU Department of Biology) also collaborate on this research. This
research is funded by the US Department of Interior Southwest Fire Initiative,
NAU Ecological Restoration Institute, and NAU Merriam-Powell Center for Environmental
Research.
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| Ecophysiological and environmental controls on tree-dwarf mistletoe interactions
M.S. student Chris Bickford (cb93@dana.ucc.nau.edu)
is studying the influence of light and water stress on germination and establishment
of dwarf mistletoes (Arceuthobium spp.) that parasitize ponderosa pine,
lodgepole pine, Douglas-fir, and western hemlock in a controlled, greenhouse
experiment performed. This research will increase understanding of factors
that influence the population dynamics of dwarf mistletoes. Brian Geils
(USDA Rocky Mountain Research Station) collaborates on this research.
This research is funded by the NAU School of Forestry Mission Research and
the McIntire Stennis Programs, and the USDA Rocky Mountain Research Station.
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| Seasonal dynamics in bark beetle flights and ponderosa pine growth and physiology
M.S. student Monica Gaylord (monicagaylord@yahoo.com)
is measuring seasonal variation (January to December) in flights of several
Dendroctonus and Ips bark beetles and physiological and growth
characteristics of ponderosa pine (pre- and mid-day xylem water potentials,
midday net photosynthetic rate and stomatal conductance, resin flow in response
to phloem wounding, growth of xylem, stems, and roots) at the NAU Centennial
Forest. The purpose of this research is to test the hypothesis that
flights of some bark beetle species occur when tree resin defenses are high
as a result of the unusual seasonal pattern of tree growth and water stress
in northern Arizona. This hypothesis may help explain the lack of historic
bark beetle outbreaks in northern Arizona in a landscape of trees highly stressed
by drought and competition. Mike Wagner (NAU School of Forestry), Eric
Smith, and Drew McMahan (USDA Forest Service Forest Health Technology Enterprise
Team) collaborate on this research. This project is funded by the NAU
School of Forestry Mission Research and McIntire Stennis Programs, and the
USDA Forest Health Technology Enterprise Team.
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| Effects of fire and competition from native plants on knapweed invasion in southwestern ponderosa pine forests
M.S. student Barbara Satink (barb@wolfsonphotos.com)
is studying how fire disturbance and competition from native plants affects
establishment of an exotic, noxious weed, diffuse knapweed (Centaurea diffusa),
in ponderosa pine forests of northern Arizona. Karen Clancy and Carolyn
Sieg (USDA Forest Service Rocky Mountain Research Station) collaborate on
this research. This research is funded by the USDA Rocky Mountain Research
Station.
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| Restoration of wet meadows: Influence of burning herbaceous communities on groundwater recharge
I collaborate with M.S. student Gina Mullen (NAU Environmental
Science and Policy Program,
gina.mullen@nau.edu) and Abe Springer (NAU Department of Geology,
abe.springer@nau.edu) on a study of the influence of prescribed burning
on soil water content and ground water recharge of wet meadow vegetation at
Hart Prairie, Coconino National Forest, Arizona. This research is funded
by the US Department of Interior Southwest Fire Initiative and NAU Ecological
Restoration Institute.
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| Insect population and tree resistance responses to restoration thinning treatments in ponderosa pine forests
This project started in 2000 and has included the work
of former M.S. student Kjerstin Skov (kjerstin@selway.umt.edu, currently working
on a Ph.D. at the University of Montana), former post-doc Kimberly Wallin,
and current post-doc Natacha Guerard (Natacha.Guerard@nau.edu).
The overall purpose of this research is to evaluate effects of forest restoration
treatments on ponderosa pine growth and resistance to bark beetles.
The results of 2000-2002 research have been published or are in review
(see publication lists, papers by Skov et al. and Wallin et al.). Natacha
Guerard is currently working on three studies: 1) Evaluation of the role of
ponderosa pine tree size resistance to Dendroctonus and Ips
bark beetles, 2) genetic variation in ponderosa pine resistance to Dendroctonus
and Ips bark beetles, and 3) long-term effects of thinning on ponderosa
pine resistance to Dendroctonus and Ips bark beetles.
Mike Wagner (NAU School of Forestry) collaborates on this research.
The research is funded by the USDA Rocky Mountain Research Station.
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| A stable isotope analysis of riparian tree water sources along a gradient of ground water availability
This research is a continuation of Jonathan Horton’s (johorton@vt.edu)
PhD dissertation at NAU. We are using stable isotopes of oxygen and hydrogen
to study water sources used by two native riparian trees, Fremont cottonwood
(Populus fremontii) and Gooding willow (Salix goodingii), and
one exotic, invasive shrub, tamarisk (Tamarix chinensis) along a gradient
of ground water availability at two rivers in central Arizona (Bill Williams
River, Hassayampa River). The purpose of this research is to better
understand environmental and physiological factors that promote tamarisk invasion
of riparian ecosystems. Steve Hart (NAU School of Forestry) collaborates
on this research. The research was funded by the NAU Mission Reserch
and McIntire Stennis Programs, the National Science Foundation, and the EPA
STAR Fellowship Program.
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| Genetic variation in Douglas-fir resistance mechanisms to the western spruce budworm
This research is a continuation of Zhong Chen’s (zc2@dana.ucc.nau.edu)
PhD dissertation at NAU. We are working on the publication of one more
paper that address the role of foliar nutrients in resistance of Douglas-fir
to western spruce budworm defoliation. Five other papers on resistance
of Douglas-fir to budworm defoliation have been published recently from Zhong’s
dissertation (see papers by Chen et al. under publications). Karen Clancy
(USDA Forest Service Rocky Mountain Research Station) collaborates on this
research. This research was funded by the NAU Mission Research and McIntire
Stennis Programs, and the USDA Rocky Mountain Research Station.
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