Agriculture Reference
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native grasses, forbs, and shrubs, although cattle grazing was not effective in
controlling shrubs. Thomas (1985) found that grazing sheep reduced heavy
brush infestation of the palatable Ceonothus integerrimus , but consumed very
little Arctostaphylos patula . He concluded that to avoid unfavorable shifts in
botanical composition to unpalatable species and a loss of effectiveness of
grazing for vegetation control, grazing must be managed not only to avoid
damage to trees, but also to promote recovery of palatable browse and herba-
ceous species.
Recommended management of grazing for vegetation control without
damage to associated needleleaf trees follows principles already described for
geese grazing. Uniform grazing, careful balancing of animal grazing with
available forage, and avoiding routine animal concentration in the same areas
within the plantation can be achieved by careful placement of salt and water,
riders or herders to observe and manage livestock grazing and behavior, and
grazing of the plantation when available forage is most palatable (Krueger,
1985). Uniform grazing with limited damage to trees was easier to achieve by
grazing 25% to 600% more animals than standard practice in the area, and
managing them more carefully, rather than reducing stocking rate (Monfore,
1983).If an individual herd or flock shows an inclination to browse the young
needleleaf trees, it must be removed from the plantation to another range.
Precipitation may vary greatly between and within years (Boyd,1985),making
careful and flexible grazing management based on observation essential to
high tree survival.
On many tree plantations, grazing for vegetation control may not be appli-
cable due to the inaccessibility of the site, lack of water, excessive slopes, pres-
ence of slash, or the type of vegetation. The best sites for tree growth are also
the best for the use of grazing (Krueger, 1985).
Grazing in coconut plantations
Grazing for general weed control in established tree crop plantations
is a common practice in coconuts (Payne, 1985). Grazing for vegetation man-
agement is suitable in areas with more than 2000 mm of rainfall, although
even in marginal areas (1300-2000 mm rainfall) coconuts are not clean tilled
(Santhirasegarum, 1966). Because of shading by coconut, plant species for
grazing and plantation ground cover must be adapted to irradiance levels that
are only 40%-70% of full sunlight. Grasses and legumes show different
degrees of tolerance for shade (Shelton, Humphreys & Batello, 1987). C 4
species may be more affected than C 3 species.Eriksen & Whitney (1982) found
that legumes, such as Desmodium intortum and Leucaena leucocephala , continued
to fix nitrogen, even when shaded. Humphreys (1991, p. 13) suggested that
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