Transcript ppt - University of Colorado Boulder

Riparian Zones in
Winter
“What are the differences in the tree
species between riparian zones and
upland zones in winter?”
Tim Moret
Winter Ecology – Spring 2005
Mountain Research Station – University of Colorado, Boulder
Introduction
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Riparian zone encompasses the strip of land between the stream channel
and hillslope
Sometimes referred to as the valley floor, near-stream zone
Differentiated from upland zones by unique hydrology, topography,
vegetation, and soils
Because of their location, they have significant potential to regulate the
movement of water
 elements in surface
 subsurface runoff that flows from upslope areas to the stream
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Tree species
 improve fish and wildlife habitat
 act as nutrient sinks
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As interest in water quality increases, riparian zone management is
improving and evolving
 people are looking for tree species that grow well in areas that are periodically
flooded.
What is important about tree
species in riparian habitats?
 Trees are very effective
nutrient filters
 can modify some
environmental impacts of
agricultural practices.
 act as nutrient sinks
 Tree species improve fish and
wildlife habitat
 food and shelter
 Ecology improved by species
of trees that are fairly flood
resistant
 can be a problem especially
with rapid snowmelt in the
mountains.
What kinds of trees are
found in Colorado mountain
riparian zones?
 Trembling or Quaking Aspen
 River (Water) Birch
 Arroyo Willows (29 different
species)
 Thin-leaf Alders
 Narrow-leaf Cottonwood
 Box-Elder
 Rocky Mountain Maple
 Shrubs
 Ashes
 Blue Spruce
How does that differ from
upland zones in the
mountains?
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Lodgepole Pines
Englemann Spruces
Douglas Firs
Limber Pine
Sub-Alpine Fir
Ponderosa Pine
White Fir
White Pine
Colorado Blue Spruce
Aspen and Gamble Oak
Why the discrepancy?
 The big factors are water and sunlight.
 Conifers need less water to survive
 slower growers than the local deciduous trees
 This leads to the conifers being able to spread farther out
 leaving the riparian space to those who need it
 Conifers also need less sunlight whereas the deciduous trees need a
lot more
 Deciduous then flock to where the dense conifer canopy is parted
 they can receive more direct rays
 Deciduous do most of their growing in the summer months able to shed
their leaves
 Evergreen grow all year round so they must retain their needles
 Conifers are adapted to harsher environments where their deciduous
neighbors are unable to follow, giving them reason to spread out into
the upland montane and sub-alpine environments
 So many things work in conjunction to provide this divided situation.
My Investigation
 Question: Whether the riparian zone still
supports a greater diversity of life than
the upland in winter months? What does
this mean for regional ecology?
 Diversity of life measured in the number
of species clearly identifiable to my eye in
each zone
 Take samples in different locations
Small Stream Bed near
Meeting Hall
 Distinguishable riparian zone: 10 paces by 40 paces
 Stream Width: 2 paces
 Identifiable species: 3
 Willow
 Aspen
 River Birch
 Nearby upland zone: 10 paces out on either side
 Identifiable species: 4
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Lodgepole
Englemann
Sub-Alpine
Limber
 Clearly definable boundary between zones? NO
Medium Stream Bed
Crossing Road
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Distinguishable riparian zone: 40 paces by 40 paces
Stream Width: 10 paces
Identifiable species: 8
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Nearby upland zone: 10 paces out on either side
Identifiable species: 4
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Willow
Aspen
River Birch
Alder
Shrubs (3+)
Lodgepole
Englemann
Sub-Alpine
Limber
Clearly definable boundary between zones? YES
Large Stream Bed up near
the Campground
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Distinguishable riparian zone: 60 paces by 40 paces
Stream Width: 15 paces
Identifiable species: 8
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Nearby upland zone: 10 paces out on either side
Identifiable species: 5
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Willow
Aspen
River Birch
Alder
Shrubs (3+)
Lodgepole
Englemann
Sub-Alpine
Limber
Blue Spruce
Clearly definable boundary between zones? YES
Graphed Results
Species Diversity in 3 Stream Widths
16
14
12
10
8
6
4
2
0
15
10
8 8
6
4
1
Riparian
Width
2
3
4 4
5
Stream Riparian Upland
Width Species Species
Small Stream
Medium Stream
Large Stream
Crossover of Species
Between Zones
8
8
8
7
6
5
5
4
3
2
1
4
4
3
2
1
1
1 1
0
0
Small
Medium
Large
Stream
Stream
Stream
Riparian
Deciduous
Riparian
Evergreen
Upland
Deciduous
Upland
Evergreen
Conclusions I have drawn
from my investigation
 Curious about if the advent of winter also
brought on an equalizing effect to the diversity
discrepancy between riparian zones and
upland zones…
Conclusions
 Somewhat of a change
 Some smaller plants died off because of the season
 Deciduous plants do not die in winter though, obviously,
so not as much as I might have predicted
 However, upland forests did exceed riparian zones in
smaller streams
 Leading to conclusion that size of the stream probably has an
effect on diversity it is able to sustain
 Montane forests’ diversity stayed fairly similar throughout the
testing
 But I believe that there is an equalizing effect going on
 Results not perfect
 I used the broad category of shrubs to represent at least 3+
species
 My testing area was small for testing species diversity
 My species identification is at beginner level, especially with
deciduous trees without leaves
 Death and dormant is hard to distinguish
Extrapolate to Ecological
Effects
 What does this mean for the region and why would
someone care?
 Refer back to functions of riparian zones
 Reduction in species diversity during the winter probably also
means reduction in number of plants
 Could also mean losing plants that have very important
functions
 Nutrient filtering could be impaired if it is needed in winter
because stream water is usually still flowing
 Habitat loss or food loss for local wildlife, spawning either a
press of resources or a necessary migration
 Floods may be more damaging in the winter thaw and spring
melt because the plants have not returned after the winter yet.
 However all of these issues probably deserve specified studies
of their own rather than inferences
In Summary…
 Species diversity is reduced during the
winter which may or may not have
ecological consequences
 Smaller streams will have less clearly
definable boundaries between their zones,
making winter’s effect more pronounced
 Larger streams will support more diversity in
general and possibly lose less in the winter
Sources
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Dickson, James G. “Managing Streamside Zones for Wildlife.” NWTF Wildlife
Bulletin No. 17
Colorado Native Plant Society. “Suggested Native Plants for Horticultural Use on
the Front Range of Colorado.” Revised April 2001.
Barkley, Yvonne Carree and Ron Mahoney. “Riparian Zone Tree Plantings.” UI
Extension Forestry Information Series. Tree Planting and Care No. 3. University of
Idaho.
McGlynn, B.L. In press. The role of riparian zones in steep mountain catchments.
in Global Change and Mountain Regions. “Advances in Global Change Research
book series”, Martin Beniston (ed), Kluwer.
“Trees Along Streams.” Forest and Wildlife Benefits on Private Lands. Missouri
Department of Conservation. Copyright 1994.
“Biotic Communities of the Colorado Plateau.” Land Use History of North America:
Colorado Plateau. http://www.cpluhna.nau.edu/Biota/mixedconifer.htm.
USDA Forest Service. 1993. “Changing conditions in southwestern forests and
implications on land stewardship. U.S. Forest Service, Southwest Region,
Albuquerque, N.M., 8 pp.
Weber, William A. Rocky Mountain Flora. University of Colorado Press. Copyright
1967