July 1963
Volume
Number
61
7
About This File: This file was created by scanning the
printed publication. Misscans identified by the software
have been corrected; however, some mistakes may remain.
JULY 1963
531
each liner in 1961 was 36 cents,
Seed-Trap Liners of Nylon Tent Screening
Abstract. Rapid, accurate collection
of seed and litter samplesis possible
when inexpensive,nylon seed-trap liners are used. Besides preventing the
loss of small seedsand piecesof litter
through the. bottom screen of conven-
tional seedtraps, chancesof spilling
collected material are minimized. Liners
are especiallyconvenientwhenseedand
htter collectionsare wet. After drying
of nylon wrapped contents, a simple
rinsing and drying prepares liners for
re-use.
Seed traps strategically placed
in a forest stand sample seed production and permit estimates of
seed fall distribution and perio-
which
Packaged liners and contents are
dried
at 60 ø to 65 ø C. soon after
collection.Liners are then removed,
and
seed
and
litter
contents
re-
turned to their labeled bags.Liners
are rinsed in warm water, dried in
lots of 10 or 12 over metal
clothes
included
20 cents for hem-
ming.
To hold the nylon liners in place,
6d galvanized casing-head nails
were driven into the base piece.of
the top seed-trap section, leaving
not more than •
inch of the nail
head protruding. In order to accommodatethe nails, •-inch-diam-
hangers, and are again ready for
use. Hung wet, nylon screening eter holes were drilled in the upper
dries nearly wrinkle-free without strips of the bottom seed-trap secpressing or stretching.
tion. Holes, larger in diameter
For the study in which these than the nails, were found necestrap liners are used,seedand litter sary to prevent snaggingand pullcollections are made four times a
year. Two liners are required per
trap as they are exchangedat each
collection. Thus, each liner is exdicity of dispersal. They also proposed six months of the year. Even
vide similar
estimates for litter
with
this amount of weathering,
fall.
however, liner life is estimated to
The accumulation in each trap be at least three years.
should be as representative of true
Seed traps used with nylon tent
seed and litter production as pos- screening have an effective catchsible. Inaccurate
estimates result
merit area of about 2 square feet,
when trap contentsare accidentally with dimensions of 12• inches
lost during collectionor when small X 24 inches. Each seed trap has
seed and pieces of litter escape three parts--a top piece with 3through trap screenswith too large mesh galvanized hardware screen
mesh.
cloth, the hemmed 28-mesh nylon
To eliminate these difficulties, a tent screen liner, and a bottom secremovable seed-trap liner was fab- tion of 18-mesh aluminum screen
ricated from nylon tent screening wire (Fig. 1). The nylon tent
--a lightweight, d u r a b 1 e, non- screeningwas cut slightly oversize
shrinking, and inexpensive mate- --14 inches X 26 inches--to insure
rial. These trap liners have been complete coverage and facilitate
tested in coastal Washington's liner replacement. Total cost of
western hemlock forest type on the
Hemlock Experimental Forest• near
Grays Harbor.
Nylon seed-trap liners have several advantages. Because they are
easily removed, accidental spilling
ing of the nylon fabric. When the
liner was positioned over the bottom section,the mating nails in the
top sectionheld it in positionwithout damage. The complete assembly hassuccessfully
withstoodwind
and rain
disturbance
and minor
displacementcausedby animals or
falling tree limbs.
Current
studies of western hem-
lock seedproduction and dispersal
have been made more efficient by
use of the nylon seed-trap liner.
Successhere, after undergoingfurther tests of efficiencyand durabiL
ity under westernWashingtonconditions, suggeststesting of these
liners in other forest types and
climatic
conditions.
FRANCIS R. HERMAN
Pacific lgorthwest Forest
and Range •xpt. Sta.,
Forest Service, U.S. Dept. •tgric.,
Portland, Ore.
A
is prevented; and collection time
is reducedby elimination of scraping and pouring trap contentsinto
collection containers. The fine nylon mesh prevents loss of small
hemlock and western
redcedar
seeds
and small pieces of litter. If seed
and litter collections are wet, much
C
of the water can be quickly eliminated by hand-centrifuging the
liners before they are placed in
plastic, waxed paper, or ordinary
kraft bags. Liners and contents
thus packaged are readily labeled
for identification during drying
and later examinations
litter.
of seed and
tMaintained
jointly by the Pacific
Northwest Forest and Range Expt. Sta.
and St. Regis Paper Co.
FIG. 1.--Seed traps used to sample western hemlock seed production and dispersal
consist of three parts: top section, liner of nylon screening, and bottom section.
A showsassembledseed trap with liner; B is an unassembledview; ½ is an enlargement showing details of construction.