The relationship between riparian areas and biological

diversity

A comparison of streams in eastern Colorado and southwestern Virginia

By Ann Widmer 12-9-03

EPA’s need for monitoring…

EPA Administrator William Reilly (1989)—

“Good News– Based on my years in the environmental movement, I think the Agency does an exemplary job of protecting the nation’s public health and quality of the environment. Bad news– I can’t prove it.”

http://www.epa.gov/emap.html

(environmental monitoring and assessment program)

Key components:

statistical design wide-scale application across the country use of biological indicators

What is an indicator? An instrument for monitoring the

operation or condition of a physical system

» Webster’s II New Riverside University Dictionary

EMAP Measurements

Fish assemblage Benthic macroinvertebrates Periphyton Water quality Habitat parameters

– Substrates– Embeddedness– Riparian vegetation

Plecoptera (stonefly)

Periphyton on river rocks

Do indicators work?

(Are they a good measure of ecological health?)

2 healthy aquatic systems

Completely different stream character.

My project

EMAP sampling in Colorado– Concerns – Qualitative data

Comparison of trends to those in southwest Virginia– Development of indicies– Intensively studied area

Trends in southwest Virginia

1. As riparian vegetation is decreased, fish and mussel species diversity is decreased

Diamond, J.M., and V.B. Serveiss. 2001. Identifying sources of stress to native aquatic fauna using a watershed ecological risk assessment framework. Environmental Science Technology 35: 4711-4718.

Trends in southwest Virginia2. As riparian vegetation is decreased,

benthic macroinvertebrate density is decreased. Effect more pronounced very locally (within 200 meters)

Sponseller, R.A., E.F. Benfield, and H.M. Valett. 2001. Relationships between land use, spatial scale, and stream macroinvertebrate communities. Freshwater Biology 46: 1409-1424.

Colorado streams(variation with elevation)

Above timberline

Colorado streams(variation with elevation)

Forested mountain

Colorado streams(variation with elevation)

Urban– Front Range

Colorado streams(variation with elevation)

Plains

Contrary trends?

Above timberline

Forested mountain

Urban–

Front Range

Plains

Riparian vegetation (relative to stream size)

1 4 3 2

Macro-

invertebrate diversity

1 4 3 2

Fish species diversity

1 2 3 4

Additional considerations…

Scale– Virginia studies were in a small watershed– Colorado study encompasses half a state–

compare within similar conditions Sedimentation Land use and fish stocking Water quality

Comparison of similar streams

Bear Creek, CO Boulder Creek, CO Clear Creek, CO

– Found the highest fish species diversity and density in the Bear Creek, the one with the most riparian vegetation

Recommendations to the EPA

Indicators should not be used to compare health of dissimilar streams – Different states – big difference in riparian size– Different elevation– Different stream order

Indicators most useful when comparing the same site over time– environmental monitoring