Cumulative Impact Estimation For Landscape

Scale Forest Planning

Finn Krogstad & Peter SchiessForest Engineering, U. Washington

OUTLINE

PROBLEM: Evaluating Landscape Plans

APPROACH: Hydrologic Modeling in GIS

QUESTION:What is ‘Cumulative Impact’?

PLANNING IN TIME AND SPACE

DETAIL

COMPARING ALTERNATIVES

ECONOMICS

• Timber Yield

• Road Costs

ENVIRONMENT

• Sediment

• Water

• etc.

MODELING OBJECTIVES

Input - entire landscape plans

Output - cumulative impacts ratio

Simplicity - for general users

Transparency - assumptions & processes

Modularity - alternate models

Consistency - watershed analysis

Compatibility - ArcInfo GIS system

Robustness - relative rather than absolute

HYDROLOGIC MODELING IN GIS

Divide the problem into component modules of production, routing, and accumulation.

coarsesediment

finesediment

peakflows

LWDshade

cumulative impact

stream sensitivity/resource vulnerability

stands/roadstopography

soils

harvestingconstruction

fire/blowdown

Events Maps

masswasting

surfaceerosion

rain-on-snow/road interception

GRIDDING THE WORLD

PROCESS LOCALLY

All physical processes are local in nature.

INTEGRATE GLOBALLY

Impacts can accumulate across space, time and management activities.

CUMULATIVE IMPACT

1. Different sources

For example, fine sediment:– roads– harvest– streambank– landslide

CUMULATIVE IMPACT

1. Different sources

2. Different reaches– ‘a reach is a reach’– reach sensitivity– habitat location– habitat quality

CUMULATIVE IMPACT

1. Different sources

2. Different reaches

3. Different years– catastrophic vs. chronic– species life history

CUMULATIVE IMPACT

1. Different sources

2. Different reaches

3. Different years

4. Different inputs

production

delivery

accumulation

sensitivity

vulnerability

Stream shade

production

delivery

accumulation

sensitivity

vulnerability

Wood

production

delivery

accumulation

sensitivity

vulnerability

Fine sed

production

delivery

accumulation

sensitivity

vulnerability

Peakflow

production

delivery

accumulation

sensitivity

vulnerability

Coarse sed

Cumulative Impact

CUMULATIVE IMPACT

1. Different sources

2. Different reaches

3. Different years

4. Different inputs

5. Different species– salmon vs. elk vs. frogs

CONCLUSIONS

This approach goes beyond the accuracy of current models and data, but it should be pursued because:

1. Even flawed predictions provide insight

2. Improve models with observations

3. Crude predictions vs. broad regulations