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Journal Publications
Larter N.C. and Nagy. J.A. 2001 Seasonal
and annual variability in the quality of important forage plants on Banks
Island, Canadian High Arctic Applied Vegetation Science 4: 115-128
(PDF = 186 KB)
Abstract.
In vitro acid-pepsin digestibility
(IVDMD), crude protein (CP), fibre, lignin, and energy content were measured
for a variety of forage plants collected annually from Banks Island over
five summers and three winters from 1993-1998. Summer samples were collected
during mid-June (start of growing season), mid-July (peak of growing
season), and midlate August (senescence). Winter samples were collected in
early (November), mid- (February), and late- (April/May) winter. Samples,
collected in areas of both high and low muskox density, included Carex
aquatilis, unidentified Carex, Salix arctica, Dryas integrifolia, Cassiope
tetragona, Saxifraga spp., Astragalus spp., Oxytropis spp., lichen, and
grass. Seasonal
dynamics in forage quality during the growing season were similar to those
reported elsewhere in the arctic and high arctic and were consistent across
years. However, there were significant year effects in lignin, fibre, and
energy content of forages and the crude protein (CP) content of C. aquatilis
in winter, indicating annual differences in the quality of forage available
to herbivores. The quality of forages on Banks Island was similar between
areas subjected to different densities of muskox (ca. 1.6 - 1.9 versus 0.3 -
0.4/km2) implying that quality was not affected by these grazing
intensities. The Banks Island high arctic ecosystem supports an abundance of
herbivores. It has been hypothesized that this is because forage quality
and/or quantity are superior on Banks Island than elsewhere in the high
arctic. Our results regarding forage quality are equivocal. Although the
maximum CP content of forages from Banks Island was generally higher than
reported elsewhere in the arctic and high arctic, CP content reported
elsewhere fell within the interannual range reported from Banks Island.
Fibre and energy content of forages from Banks Island were similar to
slightly lower than elsewhere in the arctic and high arctic. Such
comparisons must be considered in light of the interannual variability in
quality we report. |
