WRC Paired Watershed Studies Overview - knowyourforest.org · Oregon is Not Alone and Watershed Studies are Not New From Ice and Stednick 2004 •Ice and Stednick (2004, Forest History

WRC Paired Watershed Studies Overview

Examining the Effects of Contemporary Forest Practices on Aquatic Ecosystems at Multiple Scales

Liz Dent, ODF Deputy Division Chief, State Forests Maryanne Reiter, Hydrologist, Weyerhaeuser NR Co. Presented at WRC Policy Workshop, November 13,2013

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Oregon is Not Alone and Watershed Studies are Not New

From Ice and Stednick 2004

• Ice and Stednick (2004, Forest History Today) chronicle contributions of Paired Watershed Studies

• 13 studies through United States: Wagon Wheel Gap 1910 – Improved understanding of

hydrology

– Forest management affects on hydrology

– Establishment and refinement of BMPS to protect watershed functions.

Brazier and Brown 1973

Brown and Krygier 1967

Cornerstone Findings and Policy Changes WRC Workshop

• Temperatures increase without stream buffers: Leave trees around streams

• Dissolved oxygen decreases with excessive slash accumulation: Keep slash out of streams

• Roads major sources of sediment: BMPs to reduce sediment delivery from roads

Science and Policy

Studies designed to inform policy decisions

Scientific findings are becoming available

Need to make sure that findings are making their way to the policy dialogue

Need to make sure the science is being framed in a way that supports the policy process

WRC Workshop

• Linking forest management to a range of aquatic responses.

• Further knowledge of ecosystem processes in the context of working forests.

Background Why watershed studies are important

Linking small headwater stream to downstream responses

WRC Background

What are the effects of forest harvest on small streams? If changes are observed are they also observed downstream?

Linking physical to biological responses WRC Background

If there are changes in the physical or chemical characteristics of the stream- what does that mean for the biology?

Goal: Quantify effects of contemporary forest practices on the physical, chemical and biological characteristics of streams at multiple spatial scales. Approach: Cooperative, multi-disciplinary and long-term.

Oregon Watersheds Research Cooperative Background

Conceptual Model of Linkages

Light

Temperature

Nutrient availability

Primary producers (Algae, Bryophytes)

Detritus, Leaf Litter,

Organic Matter

Invertebrates

Stream Flow

Amphibians

Fish

Geomorphology & Soils

Turbidity & Sediment

Riparian Vegetation

Background

“Simple” connections within the forested aquatic ecosystems. Basis for predicting system responses to forest management.

Hinkle Creek Study Hinkle Creek

First of the three contemporary paired watershed studies in Western Oregon.

Watershed Study Design

Design: Nested, Paired Watershed area: 4796 acres Control watershed: 2117 acres Treatment watershed: 2679 acres Treatments: First harvest: 5 clearcuts adjacent to non-fish bearing streams (2005). Second harvest: 4 clearcuts adjacent tributary and mainstem fish bearing streams (2008). Status: Study ran from 2001-2011

Hinkle Creek

First Harvest in Small, Headwater Streams Hinkle Creek

Increase

Decrease

No change

Didn’t measure

Second Harvest Along Fish-Bearing Streams Hinkle Creek

Increase

Decrease

No change

Didn’t measure

4 Clearcuts = 324 acres Fish bearing streams With Overstory buffer

NBL

NB6

NB7

Alsea Watershed Study: Then and Now Alsea Revisited

Alsea Watershed Study (1966):

• Entire watershed harvested

• Burned with no stream buffers.

1966 2009

Current forest practice rules: •Minimize clearcut to 120 acres • Buffers on fish-bearing streams • Prohibit excessive slash in streams.

Hydrology 1966

• Increases in low flows

• Small increases in peak flows

Hydrology 2009

• Increase during transition months

Hydrology Response to Harvest Alsea Revisited

Sediment Response to Harvest

1966

• Sediment increased (hot prescribed fire and channel disturbance)

2009

• Preliminary results indicate no major increases in sediment

Alsea Revisited

Stream Temperature Response to Harvest

Temperature 1966

• Increased >10 deg C

Temperature 2009

• Increased < 1.0 deg C in the buffered and un-buffered portion

Alsea Revisited

Dissolved Oxygen Response to Harvest

Dissolved Oxygen 1966

• Decreases in DO concentrations

Dissolved Oxygen 2009

• Little to no change in DO

Alsea Revisited

Fish Response to Harvest

Fish 1966

• Long-term depression of cutthroat trout population

Fish 2009

• Increased cutthroat trout biomass and abundance post harvest

Alsea Revisited

Trask Watershed Study Introduction Trask River

•The 6500 acres •Headwaters of the Trask River •West side of Oregon Coast Range Crest

Mostly State and Private ownership with some Federal lands Numerous cooperators

Nested design : local and downstream sites Size: 6500 acres Treatment: Small headwater catchments (average of 93 acres) Extensive pre- and post-harvest study: 4+ years of pre-harvest and 4 year post-harvest data collection.

Trask Study Design Trask River

Conceptual Model of Linkages Trask River

• Effects of forest harvest on the physical, chemical and biological characteristics of small headwater streams

• Extent to which harvest influences the physical, chemical and biological characteristics in downstream fish reaches.

• Increase understanding of major processes that influence aquatic ecosystems through forest-stream interactions.

2006-11 2011 2012 2012-16 Baseline Road Headwater Post-treatment data collection upgrades harvest in data collection 8 basins

Study Timeline Trask River

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Tillamook Burn, burned and cut - Oreg. State Univ. Archives, Agr. Exp. Sta. Photo. Collec., Wildfire Risk Explorer, P029:Acc 87:6

• Landscape key to understanding pattern and process, • Physical and biological context as an early phase of research

Understanding The Landscape

•Trask Landscape Setting •Physical Setting •Fire History and Vegetation •Recent Management •The Aquatic Environment

Trask River

8/1/20107/21/20107/11/20107/1/20106/21/20106/11/20106/1/2010

350

300

250

200

150

100

Date Time

Sta

ge

(m

m)

PH 1 well stage (mm)

PH 2 well stage (mm)

PH 3 well stage (mm)

PH 4 well stage (mm)

Variable

Pothole Cr small well stages (mm)

Earthflow terrain

The small watersheds with more earthflow terrain: • Less responsive to rainfall • Moderated drop in summer flow.

Low Flow Hydrology Trask River

• N:P ratios indicate biological activity

• Most sites Phosphorus limited

• Pothole cluster is Nitrogen limited

• Some sites (example: Gus1) highly variable over time while some are more consistent

• Will pattern change after harvest and how does it affect aquatic biota?

Trask Watershed StudyNitrogen & Phosphorus Ratios<15 = N limitation, >15 = P limitation

Site

PH

2P

H3

PH

4P

HD

SG

S1

GS

2G

S3

GS

DS

UM

1U

M2

UM

3U

MD

SR

K1

RK

3R

KD

S

Ratio

0

15

30

45

60

75

90

105

120

135

150

165Aug 2006

April 2007

May 2008

June 2008

Water Chemistry Trask River

Amphibian Abundance and Movement

Initial Results

• Tailed frog larvae: – Greater downstream movement than

Pacific Giant Salamanders

• Tailed frog abundance: – Increases in a downstream direction

– Higher abundance below downstream boundary of treatment areas (prior to harvest)

• Downstream sites: – Maintain mass during advanced

development stages better than headwater sites

B. McCreary

Trask River

• Fish Growth: Fastest for small salmon and trout, and minimal for larger coastal cutthroat trout.

• Movement: Restricted for coastal cutthroat trout.

• Overlap between seasonal patterns of diet and food limitation for salmonids and sculpins.

Linking Physical and Biological Responses: Fish Trask River

Trask Watershed Study Stable Isotopes

All Downstream Sites (Means)

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

-36.0 -34.0 -32.0 -30.0 -28.0 -26.0 -24.0 -22.0 -20.0

d13C Carbon Signal

d15N

Nit

rog

en

Sig

nal

Terrestrial Plants

Detritus

Algae

Aquatic Mosses

Invert Consumers

Vert. Herbivore

Invert. Predators

Sculpins

Salamanders

Trout & Salmon

Trask Watershed Study Stable Isotopes

All Headwater Sites (Means)

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

-36.0 -34.0 -32.0 -30.0 -28.0 -26.0 -24.0 -22.0 -20.0

d13C Carbon Signal

d15N

Nit

rog

en

Sig

nal

Terrestrial Plants

Detritus

Algae

Aquatic Mosses

Invert Consumers

Vert. Herbivore

Invert. Predators

Sculpins (absent)

Salamanders

Trout

Stable isotopes: Connections between elements of the food web

Nitrogen: Relative position

Carbon: Energy source

Will forest management shift this balance?

Trask Food Web Trask River

Contemporary Forest Watershed Studies Summary

Hinkle Creek • Designed Contemporary forest practices resulted in detectable

changes (both increases and decreases). • Changes were often difficult to detect and were within observed

variability of watershed. Alsea • Magnitude of changes far less than earlier forest practices. Trask Watershed Study • Builds on previous studies • Designed to measure differences in patterns and processes

underlying those patterns • Understanding process allow inferences to other settings • Managed forests within ecosystem context

Summary: Science Findings and Policy Decisions

• Oregon has a long history of research informing forest policy and management

• Important that we continue to ask the hard questions

• Use scientific methods to provide insights

• How do science findings help inform your policy decisions?

Northwest Oregon State Forests Management Plan

WRC Overview: Questions?

The aim of science is not to open the door to infinite wisdom, but to set a limit to infinite error.

Bertolt Brecht