Transcript Comparing Riparian Communities to Upland Communities in a

Comparing Vegetation in a
Riparian Zone to an Upland
Area in a Colorado Montane
Forest
By: Abby Branson
Vegetation Ecology, Summer 2013
Mountain Research Station, University of Colorado, Boulder
S
Introduction
S Background:
S
Riparian Area: An area that has high water content in
the soil due to the presence of a water source (ex. lake,
stream, glacier). (Bureau of Land Management 1998)
S
Upper Montane forests:
S
Elevation of the Montane between 8,000-10,000ft
S
Typical Vegetation: Lodgepole pines and Aspens
S
Climate: Cold winters, warm summers, intermittent
precipitation during the summer months.
S
Aspens require 25in of precipitation of more annually to
survive. (McMulkin et al. 2010)
S
Similar study looked at the influence of flow on riparian
vegetation along a montane river.
Question/Hypothesis
S Question:
S Is the vegetation in the riparian area along Como Creek
different from the vegetation in the upland area?
S Hypothesis:
S The vegetation in the riparian area is different in terms of
structure and composition compared to the upland area.
Reason/Importance of Study
S Reason:
S The vegetation in the riparian zone has access to a continual
water supply unlike the surrounding upland area, making
the vegetation different
S Importance:
S Conservation and management of riparian areas. (ex. The
Nature Conservancy, BLM)
Methods
S Location:
S
Como Creek, Nederland, Colorado.
S
Life Zone= Upper Montane.
S Randomization
S
Of sample sites- weak randomization, sample sites were limited by convenience
and other criteria.
S
Of plots- Meter stick throw used at sites to determine the plot location at the
sample sites, but this method was also limited by my ability to throw the meter
stick.
Methods
Experimental Design3 adjacent (paired) sites along the creek. Pseudoreplicates. Each riparian
plot was coupled with an adjacent upland plot in the upper montane
forest. No overlap among sites or plots. Only looked at the vegetation
along the stream, no plots crossed through the stream.
Methods
S General:
S
Plot size: 5m x 20m =100m2
S Composition:
S
Looked at number of species (Richness)
S
Analysis of Composition: Jaccard Index
S Structure:
S
Grouped species into Lifeforms
S
Analysis of Structure: Paired t-test comparing the lifeforms (trees, shrubs,
sub-shrubs, graminoids) in the riparian areas vs. upland areas.
Results
S Jaccard Index:
S Riparian vs. Upland= 56.45%. Very Similar.
## Riparian Spp.
56
# Upland Spp.
35
21
41
6
Results
Jaccard Index
Between Upland
and Riparian
Plots
Jaccard Index Between Upland Sites
Middle Site
47%
Top
Site
Bottom Site
55%
72%
Top Site
Middle Site
58%
•A good deal of similarity between the Upland Sites
Middle
Site
22%
Bottom 63%
Site
•Little similarity
between the
Riparian and
Upland Middle
Site
Jaccard Index Between Riparian Sites
Top Site
Middle Site
22%
Bottom Site
50%
Middle Site
32%
•Few similarities between each of the Riparian Sites
Overall the riparian sites were less similar
among one another compared to the upland
sites along the stream gradient.
Results
T-test
•Structure: No significant p-values. P-value> 0.05 within each
lifeform.
•Composition: Major differences in species richness between
riparian and upland attributed forbs and graminoids.
Number of Species
25
Comparing Lifeforms Between the Upland and
Riparian Zone
20
Riparian
Upland
15
Bars=
Standard
Error
10
5
0
Trees
Shrubs
Sub-shrubs
Lifeforms
Forbs
Graminoids
Discussion
S Why was the Jaccard Index high when comparing the riparian
zone to the upland area (JI=56%)?
S Why was there a great difference between the riparian and
upland plots at the middle creek sites (JI=22%) and between the
top riparian and mid riparian plots (JI=22%)?
22%
Middle Creek
Upland
Middle Creek
Riparian
22%
47%
Top
Upland
72%
Top Riparian
Bureau of Land Management, 1998
Micro-scale
Topography
Inconsistency
S Bottom riparian site similar to middle riparian site in terms
of micro-scale topography, however species composition
(Jaccard Index) not representative of this.
22%
Middle
Upland
Middle Riparian
58%
32%
Bottom
Upland
Bottom Riparian
63%
Bureau of Land Management, 1998
Discussion
S Where did the additional diversity come from when comparing
the upland and riparian areas?
S There were more forbs and graminoid species in the riparian plots.
S Why?
S Certainly in other riparian zones the additional diversity comes
from shrubs (e.g. willows) and small trees (e.g. alders and river
birch). (Friedman et al. 2008)
S During periods of low drainage herbs and seedlings colonize
exposed active channels. (Gregory et al. 1991)
Implications
S Because riparian sites vary greatly in
species composition along a stream
gradient, efforts focused on riparian
management and conservation would
need to protect a stream across the entire
stream gradient to preserve the entire
community.
Take Home
S The riparian zone did differ in
composition and structure compared the
upland area along Como Creek.
S Composition: The riparian zone had a higher species
richness
S Structure: The riparian zone contained more forbs and
graminoids compared to upland sites.
S Structure: Species were less similar along the riparian
stream gradient compared to the surrounding upland.
References
S Bureau of Land Management. 1998. Riparian Area
Management: Process for Assessing Proper Functioning
Conditions.
S Friedman et al. 2006. Transverse and Longitudinal Variation
in Woody Riparian Vegetation Along A Montane River.
Western North American Naturalist. 66(1):78-9
S Gregory et al. 1991. An Ecosystem Perspective of Riparian
Zones: Focus on links between land and water. BioScience.
41: 540-551.
S McMulkin et al. 2010. Colorado Plant
Zones.http://www.ext.colostate.edu/mg/gardennotes/511.
html. Accessed 17 July 2013.