South-Central Alaska Forests:

Inventory Highlights

Sally Campbell, Willem W.S. van Hees, and Bert Mead

United States

Department of

Agriculture

Forest 

Service

Pacific Northwest

Research Station

General Technical Report

PNW-GTR-652

September 2005
Authors

Sally Campbell is a biological scientist, Forestry Sciences Laboratory, 620 SW Main Street, 

Suite 400, Portland, OR 97205; Willem W.S. van Hees and Bert Mead are research foresters, 

Forestry Sciences Laboratory, 3301 C Street, Suite 200, Anchorage, AK 99503.

Cover photo: Kenai Lake. Photo by Stacy Allen. Olaf Kuegler
South-Central Alaska Forests:

Inventory Highlights

Sally Campbell, Willem W.S. van Hees, and Bert Mead

U.S. Department of Agriculture, Forest Service

Pacific Northwest Research Station

Portland, OR

General Technical Report PNW-GTR-652

September 2005
Ray Koleser

FIA crew hiking into plot, Bering Glacier. 
Abstract

Campbell, Sally; van Hees, Willem W.S.; Mead, Bert. 2005. South-central Alaska forests: 

inventory highlights. Gen. Tech. Rep. PNW-GTR-652. Portland, OR: U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station. 28 p.

This publication presents highlights of a recent south-central Alaska inventory conducted by 

the Pacific Northwest Research Station Forest Inventory and Analysis Program (USDA Forest 

Service). South-central Alaska has about 18.5 million acres, of which one-fifth (4 million acres) 

is forested. Species diversity is greatest in closed and open Sitka spruce forests, spruce woodlands, 

closed tall alder shrub type, and low shrub willow type. Of the forest land, 1.9 million acres are 

classified as timberland (unreserved productive forest land). About 1.3 million acres of forest 

land are reserved from harvest; these reserved forest acres are primarily on the Kenai National 

Wildlife Refuge, national parks, and the Chugach National Forest. The volume of timber on 

timberland was estimated at 5,087 million cubic feet; the plurality of volume—44 percent—is 

on state and local government lands with the remaining volume primarily on private lands (28 

percent) and national forests (23 percent). Fifty-seven percent of timberland acres and 93 percent 

of the growing-stock volume is in sawtimber stands, with Sitka spruce forest type predominating. Most timberland in south-central Alaska is of relatively low productivity, producing less than 

50 cubic feet per acre per year. For timberland acres on state and private lands, average annual 

mortality and harvest exceeded average annual growth. 

Keywords: Inventory, south-central Alaska, Kenai Peninsula, timberland, forest land.
Karen Waddell

White birch, south-central Alaska.
1

Introduction

A N INVENTORY OF THE FOREST RESOURCES in south-central Alaska was conducted 

by the Pacific Northwest Research Station Forest Inventory and Analysis Program (USDA 

Forest Service) from 2000 to 2003 (fig. 1). A more detailed presentation of the data has been 

published (van Hees 2005b). The Kenai Peninsula was also inventoried in 1987 and 2000 to assess 

spruce bark beetle (Dendroctonus rufipennis Kirby) impacts (Schulz 2003; van Hees 2004, 2005a). 

Here we summarize a portion of the information from these reports, focusing on some of the 

forestry issues in south-central Alaska: 

• What types of vegetation are present?

• How much of south-central Alaska is forest and who owns it?

• What forest land is protected from harvest? 

• How much timber is available for harvest? 

• How much of the forest is sawtimber and where is it? 

• How productive is the timberland?

• What is the rate of growth, mortality, and harvest? 

• What is the impact of the spruce bark beetle on Kenai Peninsula forests?

■ Spruce growth and mortality

■ Spruce regeneration

■ Fuel levels Ray Koleser

Crescent Lake, Kenai Peninsula.
2

Valdez

Kenai

Homer

Kodiak

Seward

Cordova

Seward

Cordova

Anchorage

A L A S K A

South-Central Alaska

2003 Inventory Area

PNW-FIA

I

0 25 50 100

Miles

Figure 1—South-central Alaska inventory area, 2003. Source: USDA Forest Service, Pacific Northwest 

Research Station, Forest Inventory and Analysis, 2005. 
3

Inventory Methods

The method used to inventory 

forest resources in south-central 

coastal Alaska was a single-phase, 

unstratified systematic-grid sample 

with grid spacing of 3 miles. 

Ground plots were established at 

each grid intersection. Sampling 

intensity was chosen to meet 

sampling error guidelines of 

±3 percent per million acres 

for productive forest area and 

±10 percent per billion cubic 

feet for net volume (actual sampling errors are 3.4 percent for 

forest land area, 5 percent for 

timberland area, and 8.4 percent 

for net volume on timberland). 

Land cover was visually interpreted for each plot by using highresolution orthophotoquads and 

high-resolution satellite imagery. 

Plots that were barren or covered 

with ice and snow were not visited on the ground. On national forest lands, 

all vegetated plots were ground visited; on other lands, only forested plots 

were visited. Ground plots were subsampled by using a cluster of four, 

24-foot fixed-radius subplots. From the first centrally located subplot, 

three other subplots were located 120 feet north, southeast, and southwest, 

respectively. Each subplot was mapped for land cover. Field plot design is 

detailed in Scott and Bechtold (1995).

Connie Hubbard

FIA crew member, Ray Koleser, on plot. 
4

Trees, if present, were sampled at each of the four subplots. Seedlings and saplings also were sampled, but with a 6.8-foot fixed-radius microplot at each subplot. 

A horizontal-vertical characterization (HV plot) of vegetation structure was made 

at the first point in each vegetation type. The HV plot had an 18.5-foot radius. 

Data collection procedures are described in USDA Forest Service (2000–2003.)

In all, 2,891 plots were located within south-central Alaska. About one-fourth 

(782) of the locations had some forested land cover whether productive, nonproductive, or inaccessible forest; of these, 439 had some productive forest on them.

Inventories were conducted in 1987 and 2000 on the Kenai Peninsula to assess 

spruce beetle impacts on the forest. These inventories used a two-phase stratified 

sample design. Ground plots were sampled with a five-point cluster of subplots. 

Inventory procedures, including down wood and regeneration measurements, are 

described in Schulz (2003), van Hees (2004), and van Hees (2005a). Walter Foss

FIA crew member, Connie Hubbard, recording plant data amid grass and downed 

wood, Kenai Peninsula.