 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

Introduction  Background:  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)  Upper Montane forests:  Elevation of the Montane between 8,000-10,000ft  Typical Vegetation: Lodgepole pines and Aspens  Climate: Cold winters, warm summers, intermittent precipitation during the summer months.  Aspens require 25in of precipitation of more annually to survive. (McMulkin et al. 2010)  Similar study looked at the influence of flow on riparian vegetation along a montane river.

Question/Hypothesis  Question:  Is the vegetation in the riparian area along Como Creek different from the vegetation in the upland area?  Hypothesis:  The vegetation in the riparian area is different in terms of structure and composition compared to the upland area.

Reason/Importance of Study  Reason:  The vegetation in the riparian zone has access to a continual water supply unlike the surrounding upland area, making the vegetation different  Importance:  Conservation and management of riparian areas. (ex. The Nature Conservancy, BLM)

Methods  Location:  Como Creek, Nederland, Colorado.  Life Zone= Upper Montane.  Randomization  Of sample sites- weak randomization, sample sites were limited by convenience and other criteria.  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 Design - 3 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  General:  Plot size : 5m x 20m =100m 2  Composition:  Looked at number of species (Richness)  Analysis of Composition: Jaccard Index  Structure:  Grouped species into Lifeforms  Analysis of Structure: Paired t-test comparing the lifeforms (trees, shrubs, sub-shrubs, graminoids) in the riparian areas vs. upland areas.

Results  Jaccard Index:  Riparian vs. Upland= 56.45%. Very Similar. # # Riparian Spp. # Upland Spp

Results Jaccard Index Between Upland and Riparian Plots Top Site 72% Middle Site 22% Bottom Site 63% Jaccard Index Between Upland Sites Top SiteMiddle Site 47% Bottom Site55%58% Jaccard Index Between Riparian Sites Top SiteMiddle Site 22% Bottom Site50%32% Few similarities between each of the Riparian Sites A good deal of similarity between the Upland Sites Little similarity between the Riparian and Upland Middle Site 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.

Discussion Middle Creek Riparian Middle Creek Upland  Why was the Jaccard Index high when comparing the riparian zone to the upland area (JI=56%)?  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%)? Micro-scale Topography Bureau of Land Management, 1998 Top Riparian Top Upland 47% 72% 22%

Inconsistency  Bottom riparian site similar to middle riparian site in terms of micro-scale topography, however species composition (Jaccard Index) not representative of this. Middle Upland Bottom Upland Middle Riparian Bottom Riparian 58% 63% 32% 22% Bureau of Land Management, 1998

Discussion  Where did the additional diversity come from when comparing the upland and riparian areas?  There were more forbs and graminoid species in the riparian plots.  Why?  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)  During periods of low drainage herbs and seedlings colonize exposed active channels. (Gregory et al. 1991)

Implications  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  The riparian zone did differ in composition and structure compared the upland area along Como Creek.  Composition: The riparian zone had a higher species richness  Structure: The riparian zone contained more forbs and graminoids compared to upland sites.  Structure: Species were less similar along the riparian stream gradient compared to the surrounding upland.

References  Bureau of Land Management Riparian Area Management: Process for Assessing Proper Functioning Conditions.  Friedman et al Transverse and Longitudinal Variation in Woody Riparian Vegetation Along A Montane River. Western North American Naturalist. 66(1):78-9  Gregory et al An Ecosystem Perspective of Riparian Zones: Focus on links between land and water. BioScience. 41:  McMulkin et al Colorado Plant Zones. html. Accessed 17 July 2013.