|
A-B
C
D-F
G-J
K-M
N-P
R-S
T-V
W-Z
W-Z
W
watershed
1. A
physiographic unit in the landscape defined by the drainage dividers around the
area drained by a particular body of water. If a lake, there is often one
watershed with subunits for contributing streams. If a river, it may be defined
for any point or all.
2. The
whole surface drainage area that contributes water to a lake. The total area
above a given point on a stream that contributes water to the flow at that point
(syn: 'drainage basin', 'catchment basin', 'river basin').
3. The
total area, regardless of size, above a given point on a waterway that
contributes runoff water to the flow at that point. A major drain-area
subdivision of a drainage basin on the basis of this
concept.
wilding
A
young seedling that develops in the wild without the help of humans. This type
of seedling is the best source of stock for some species.
windbreak
A
group of trees or shrubs in any arrangement that will afford protection from
high winds to animals or crops or both. When the arrangement is in a long line
the group is called a shelterbelt. If an associated reason is also to harvest
timber at some future date it is sometimes called a
'timberbelt'.
woodland
An
open stand of trees > 8 metres high and with a canopy cover of 40% or more,
usually among grasses. Woodland is often described by its dominant species, for
example, 'Acacia woodland', 'Acacia-Themeda woodland', 'Combretum
woodland'.
woodlot
A
small plot of trees grown for fuelwood, which can also provide small timber and
poles.
Y
yield
Plant
part harvested and the quantity of it. In agriculture, necessarily related to a
specified crop or crops or to a group of animals or to an area, and to a period
of time. For multipurpose trees, the amount of each specified part
harvested.
Z
zero-grazing
A
method of keeping animals that involves bringing fodder to them rather
than letting the animals graze freely. It is commonly done where land is in
short supply. Napier grass (Pennisetum purpureum) is a common element in
zero-grazing systems in East Africa, for example. Trees that can be lopped, like
Leuceana leucocephala, provide an important addition to these systems. So
too do trees like Acacia tortilis, which produces edible
pods.
A-B
C
D-F
G-J
K-M
N-P
R-S
T-V
W-Z
|
