d. k. shepston. department of geography, texas state university … · 2020. 9. 4. · land...

The implications of forest management in Oregon: Examining the relationship between forest cover patterns on public and private lands

D. K. Shepston. Department of Geography, Texas State University-San Marcos

IntroductionLand ownership in Oregon is a patchwork of privately owned lands and public lands owned either by the state or federal government. Forest management policies have focused on resource use and conservation in public forests, leading to potentially divergent timber extraction and forest management practices on private lands versus public lands.

Research Question

Is there a relationship between changes in forest cover on publicly managed lands and on privately managed lands?

Hypothesis: Public land forest cover will remain the same or increase between 1987 and 2001, while private land forest cover will decrease.

Important Policies Affecting Federal Forest Management(from Davis 2001; Hoberg 2001; Molina et al. 2003; Thomas et al. 2005; Charnley 2006; Diaz and Haynes 2006; McAlpine et al. 2007)

Methodology

Data

Land ownership: Gap Analysis Program USGS

Satellite Images: USGS Earth Resources Observation and Science Center

Northwest Oregon

TM (1987-1997)- July 1987

ETM+ (1999-2003)- July 2001

Normalized Difference Vegetation Index (NDVI)

Measure of reflectivity: band 3 (red), band 4 (near infrared)

Timber harvested from BLM and USFS lands = 50% of total harvests in Oregon from 1960 to 1990 (Thomas et al. 2006).

Multiple Use and Sustained Yield Act of 1960

Wilderness Act of 1964

National Environmental Policy Act of 1969

Federal Land Policy and Management Act of 1976

National Forest Management Act of 1976

Northwest Forest Policy of 1994

Landsat Satellite Imagery for 1987 and 2001 from publically available satellite imagery from the USGS Earth Resources Observation and Science Center (EROS): http://glovis.usgs.gov/.

A matrix of various land ownerships in the state of Oregon. Data for this map was obtained from the United States Geological Survey, National Biological Information Infrastructure, GAP analysis website: http://gapanalysis.nbii.gov/portal/server.pt.

Simplified land ownership distribution. The map demonstrates simplified ownership based on data from the Gap Analysis project. The land ownerships were divided into public lands (county, state, and federal) private lands, and exempted lands (military, water, Native American).

Combine data in ArcGIS 9.2

Reclassify NDVI values: Forest ≥ 0.50

Convert ownership raster to vector

Zonal statistics determine total area by ownership

Coding to allow for raster calculations

Reconvert to raster

Pixels represent 780833.84 km², multiply by number of pixels for each code

(two codes for two ownerships)= forested area

Results

Forest cover by ownership in 1987 and 2001. calculated from NDVI reclassification and simplified ownership coding, using the raster calculator in ArcGIS 9.2.

Conclusions

Hypothesis was not supported, as public lands experienced a greater loss

in forest cover than private lands.

Possible reasons:

Reclassification

Inclusion of county-level public lands

High rates of timber extraction prior to NWFP : benefits of NWFP

unmeasureable in this study

Limitations:

Image resolution too low

July satellite data is in the middle of the agricultural growing season,

when crops are quite mature

Reclassification of NDVI set too low to delineate between forests and

maturing agricultural crops

Future research directions:

Compare forest cover loss between each of the public land ownership

types and between those and private lands

ReferencesArcGIS 9.2. Environmental Systems Research Institute. San Antonio, TX.Charnley, S. (2006). The Northwest Forest Plan as a model for broad-scale ecosystem management: A social

perspective. Conservation Biology 20 (2): 330-340.Davis, S. K. 2001. Fighting over public lands. In Western Public Lands and Environmental Politics, ed. C. Davis, 11-

34. Boulder: Westview Press.Diaz, N. M. and Haynes, R. W. (2002). Highlights of science contributions to implementing the Northwest Forest

Plan—1994-1998. General Technical Report.PNW-GTR-540. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station.Earth Resources Data Analysis Systems IMAGINE. ERDAS, Inc. Norcross, GA. Hoberg, G. 2001. The emerging triumph of ecosystem management: The transformation of federal forest policy.

In Western Public Lands and Environmental Politics, ed. C. Davis, 55-85. Boulder: Westview Press.McAlpine, C. A., Spies, T. A., Norman, P., and Peterson, A. (2007). Conserving biodiversity across multiple land

ownerships: Lessons from the Northwest Forest Plan and the Southeast Queensland regional forests agreement (Australia). Biological Conservation 134: 580-592.

Molina, R., McKenzie, D., Lesher, R., Ford, J., Alegria, J., and Cutler, R. (2003). Strategic survey framework for the Northwest Forest Plan survey and management program. General Technical Report PNW-GTR-573. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station.

Table 1: Change in forested area in study region

Public Lands14565800 Km² Total Area

Private Lands19008899 Km² Total Area

Forested '87 10663066.92 km² 10708355.28 km²

Percent Forested '87 73.21% 56.33%

Forested '01 9356731.905 km² 9976713.974 km²

Percent Forested '01 64.24% 52.48%

Kilometers Change -1306335.015 km² -731641.306 km²

Percent Change -8.97% -3.85%

© Desserae Shepston 2009