Seasonal changes in chemical composition and nutritive value of native forages in a spruce-hemlock forest, southeastern Alaska.

Abstract

Twenty-two forages from Admiralty Island, southeastern Alaska, were monitored bimonthly for one year to assess seasonal changes in their chemical composition: neutral detergent fiber, acid detergent fiber, cellulose, lignin/cutin, invitro dry-matter digestibility, total nitrogen, phosphorus, potassium, calcium, magnesium, sodium, copper, manganese, iron, and zinc. Seasonal fluctuations were pronounced but generally paralleled the pulse of plant growth in spring-summer. Only minor differences were found in chemical composition of forages from two study areas and results of this study did not differ greatly from results of other studies in southeastern Alaska and the Pacific Northwest. Forbs, half-shrubs, and shrub leaves were consistently the most nutritious forages, especially during winter. Seasonally low levels of digestible energy, nitrogen, and phosphorus were identified as the most important potential limitations of these forages in meeting the nutritional needs of herbivores.

Citation

Hanley, Thomas A.; McKendrick, Jay D. 1983. Seasonal changes in chemical composition and nutritive value of native forages in a spruce-hemlock forest, southeastern Alaska. Res. Pap. PNW-RP-312. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 48 p