A review of dipterocarps - Center for International Forestry Research

Seed Handling 76
the basic activities involved in seed procurement is given
below. If a large collection region is monitored, some
seeding may be found every year; in practice, however,
logistical and other problems make annual collection from
aseasonal regions difficult.
Planning
When trees start fruiting, procurement planning has to
be initiated immediately so that good-quality planting
material can be obtained. The period between collection
and storage or sowing should be as short as possible to
reduce the chance of seed deterioration. Transport and
processing should be carefully planned and, when
necessary, the nursery advised so that germination space
is available.
Collection
The choice of collection technique for forest tree seed is
dependent on many factors, including the way the tree
disperses its seeds or fruits. For recalcitrant-seeded
dipterocarp species collecting seeds directly from the tree
crown by climbing has several advantages. These are:
a) mature seeds can be selectively collected;
b) seed from each mother tree can be kept separate when
the need arises;
c) potential losses to insect and animal interference can
be minimised; and
d) damage incurred after falling onto the ground, such
as that resulting from desiccation and ageing, can be
limited.
Generally, collections of seeds should be made from
healthy trees that have good shape and form, avoiding
trees that are obviously diseased. Inclusion of immature
seeds and seeds that have been lying on the ground for
some time should be minimised. Various methods of
collection used by the seed collection team at the Forest
Research Institute Malaysia (FRIM) are described below
along with their advantages and limitations. The methods
can be divided into two main types. Firstly, those that do
not involve climbing, the overall operation being confined
to the ground (Methods 1-3). Secondly, those involving
an element of tree climbing (Methods 4-5).
Factors to be considered for harvesting in the
aseasonal zones are given in the summary at the end of
the chapter.
1. Ground collection
Ground collection does not require employment of staff
possessing both tree climbing skills and the ability to
collect seed efficiently; the cost is thus reduced.
Nevertheless, this method necessitates good preparation:
trees must be selected and marked; and all vegetation,
debris and old or premature seeds below the trees must
be cleared. Proper supervision of collection is also
necessary. The limitations of this method are:
a) seed collection is protracted;
b) collections have to be made daily until most of the
seeds have fallen;
c) there is competition with mammals, birds and insects;
d) fungal problems, seed deterioration and premature
germination are encountered; and
e) ground cover surrounding the tree is destroyed.
2. Collection using nets or canvas
With this method, nets or canvas are laid under the tree.
This procedure is desirable in that undergrowth is not
destroyed. The limitations of this method are:
a) it is not suitable under dense undergrowth; and
b) daily collections of fallen seeds need to be made.
3. Shaking of seed-bearing branches
This method is referred to as the ‘fishing line’ method. A
local home-made catapult is used to shoot a singlefilament
fishing line, attached to a lead weight, over
smaller branches of the tree from which seed is to be
collected. A polythene rope is then pulled over the branch
and back down to the ground using the fishing line; the
rope is then pulled vigorously to shake down the seeds.
The method is suitable for small trees and for those
standing in the open. The limitations of this method are:
a) it cannot be used with very tall trees, which may be
the ones possessing the best genotypes;
b) a clear view of the terminal branches is required for
the lead weight to be aimed accurately;
c) it usually requires several attempts before the line is
satisfactorily positioned on the right branch; and
d) the lead weight and line are not fully controllable and
minor injuries may sometimes be experienced by the
operator.
4. Free climbing
This method is employed by professional tree climbers.
It involves the use of a neighbouring smaller tree for the
initial ascent, after which the climber crosses to the main
seed tree at a height where the bole is small enough to
hold safely and ascend the tree. The climber cuts off and