Abstract. Horizontal/vertical profiling is a method used to assess vegetation space occupancy. This study investigated consistency and repeatability of measurements made on plots designed to describe forest understory vegetation structure. 20 circular, 100‐m2 plots were measured by six independent observers, three times during the summer of 1997. The plots, located in south‐central Alaska, were established in a closed Picea glauca (white spruce)/Betula papyrifera (paper birch) forest. Consistency and repeatability of measurements were evaluated by examining components of variance. Response variables were absolute and relative canopy cover. Results indicate that observers were not consistent relative to each other estimating vegetative cover from one plot to the next and from one measurement period to the next, making measurements unrepeatable.
A baseline assessment of forest resources in southeast Alaska was made by using a single-phase, unstratified, systematic-grid sample, with ground plots established at each grid intersection. Ratio-of-means estimators were used to develop population estimates. Forests cover an estimated 48 percent of the 22.9-million-acre southeast Alaska inventory unit. Dominant forest types are the western hemlock-Sitka spruce, mixed conifer, and western hemlock types. The timberland portion of productive forest land for all owners is estimated to be 4.1 million acres. Net volume on timberland was estimated at 21,040 million cubic feet. Estimated gross growth of timberland forests exceeded estimated mortality by 55.8 million cubic feet. Field data collection was conducted from 1995 to 2000, and data compilation progressed through 2002.Keywords: Forest surveys, timber resources, statistics (forest), Alaska (southeast). SummaryThe southeast Alaska panhandle, 22.9 million acres, stretches from Yakutat Bay at the northern end to Dixon Entrance at the southern end. It is a large and physiographically complex region-the result of collision of several crustal plates with the North American continent. Terrain that is generally mountainous, in concert with a maritime climate, contributes dramatically to the diverse character of the forest resource. Wind and precipitation patterns, influenced by the terrain, have substantial impact on forest composition, structure, and distribution.A baseline assessment of forest resources in southeast Alaska was made by using a single-phase, unstratified, systematic-grid sample, with ground plots established at each grid intersection. Each plot consisted of a cluster of four subplots. At each subplot, tree, seedling, vegetation structure, and down wood measurements were made.Forest cover of the 22.9-million-acre southeast Alaska inventory unit is estimated to be about 11.0 million acres. Dominant forest types are the western hemlock-Sitka spruce (3.3 million acres), mixed conifer (2.4 million acres), and western hemlock types (1.8 million acres.) (See "Names of Trees" for scientific names.) Estimates of the timberland portion (not withdrawn from timber use) of productive forest land and net volume on timberland are 4.1 million acres and 21,040 million cubic feet respectively. The average timberland acre supports about 5,100 cubic feet of net volume. Estimated gross growth of timberland forests exceeded mortality by 55.8 million cubic feet. Field data collection was conducted from 1995 to 2000, and data compilation progressed through 2002.
estimates are presented of forest resource area, timber volume, and growth and mortality of timber on unreserved national forest land in the Ketchikan inventory unit of the Tongass National Forest. Pacific Northwest Research Station, Forest Inventory and Analysis, crews collected inventory data from 1995 to 1998. Productive forest land area (timberland) was estimated at 1,295 thousand acres, cubic-foot volume on timberland at 7,448 million cubic feet, and net annual growth and mortality at 11,003 and 50,426 thousand cubic feet, respectively.
Agriculture is dedicated to the principle of multiple use management of the Nation's forest resources for sustained yields of wood, water, forage, wildlife, and recreation. Through forestry research, cooperation with the States and private forest owners, and management of the National Forests and National Grasslands, it strives-as directed by Congress-to provide increasingly greater service to a growing Nation. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, sexual orientation, and marital or family status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326-W, Whitten Building, 14 th and independence Avenue, SW, Washington, DC 20250-9410 or call (202) 720-5964 (voice or TDD). USDA is an equal opportunity provider and employer. USDA is committed to making its information materials accessible to all USDA customers and employees.
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