Historic, Archive Document
Do not assume content reflects current
scientific knowledge, policies, or practices.
FOREST SERVICE RESEARCgf
(i%'ia973
SEED SOURCE VARIATION IN
PUERTO RICO AND VIRGIN ISLANDS
GROWN MAHOGANIES
BY T. F. GEARY, H. BARRES, AND R. YBARRA-CORONADO
INSTITUTE OF TROPICAL FORESTRY
RIO PIEDRAS, PUERTO RICO
FOREST SERVICE
U. S. DEPARTMENT OF AGRICULTURE
SUMMARY
Seeds were
collected from
natural
stands of Swietenia macrophylla and Swietenia humilis
in
eighteen
areas from Mexico
through Panama and
seedlings from
the
seeds were
planted
at
thirteen
locations
in
Puerto
Rico
and
the
Virgin
Islands.
Swietenia
mahagoni
from
naturalized stands in the Virgin Islands were included
in the plantings.
Differences
exist
to
varying
degrees
in
seed
pods,
seedling
characteristics,
survival
after
field
planting,
susceptibility
to
shoot
borer
attack,
growth
rate
and
leaf
characteristics
between
species
and among
seed
sources
within
species.
Differences between
species were
more
important
than
differences
among
seed
sources
in
the
important
characteristic
of
adaptability
as a timber species.
Planting location was also very important.
S.
macrophylla
is recommended for plantations in most of the Subtropical Moist and Wet
Ecological
Life
Zones,
but
only
on
a
small
scale
because
of
shoot
borer
and
weed
problems. The
data
suggest
that
native
areas with
the
shortest
dry season may be the best
source
of
seed
for
S.
macrophylla
plantations
in
Puerto
Rico.
No
mahogany
is
recommended
for
the
coolest,
wettest
portion
of
the
Subtropical Wet
Life
Zone
or
the
Subtropical
Lower Montane Wet
Zone. A
hybrid,
S.
macrophylla
x
S.
mahagoni,
is
the
mahogany
for
planting
for timber production
in
the
Subtropical Dry
and
transitional
area
of the Subtropical Moist Zone.
O.D.C.232. 12: 176.1
Swietenia:
(729.5)
RESUMEN
Se
escogieron
semillas de Swietenia macrophylla y Swietenia
humilis de rodales naturales
en
18
areas desde Mexico
hasta Panama,
y
las
plantulas de
estas
semillas
fueron plantadas
en
trece
sitios
en
Puerto
Rico
y
las
Islas
Virgenes.
En
estas
plantaciones
se
incluyo
Swietenia mahagoni de rodales naturalizados en
Islas Virgenes.
Hay
diferencias,
hasta
cierto
grado,
en
la
forma
de
las
bellotas,
caracteristicas
de
las
plantulas,
grado
de
supervivencia
despues
de
plantadas,
susceptibilidad
al
ataque
del
barrenador,
grado
de
crecimiento
y
caracteristicas
de
la
hoja,
entre
las
especies
y
la
procedencia
de
las
semillas. Las diferencias entre especies resultaron mas importantes que
las
diferencias
entre procedencias, en su importante
caracteristica de adaptabilidad como
especie
maderable. Tambien fue muy importante
el
sitio donde
se plantaron.
S.
macrophylla
es recomendada
para
la
mayoria
de
las plantaciones en Zonas de Vida
Ecologica Muy Humeda y Humeda Subtropical,
pero
solamente
en pequena
escala, debido
a
los problemas causados por
el
barrenador y
los yerbajos. Los datos adquiridos sugieren que
las areas nativas que tienen una temporada de sequia corta podrian
ser
la mejor procedencia
para
plantaciones de
S.
macrophylla
en
Puerto
Rico. No
se recomienda ninguna caoba para
la
parte mas
fresca
y mas humeda
de
la Zona Muy Humeda
Subtropical o
para
la Zona
Muy Humeda Montano Bajo
Subtropical.
Para
la
produccion
de madera
en
la Zona
Seca
Subtropical
y
en
el
area
transitoria
de
la
Zona
Humeda
Subtropical
la
hibrida,
S.
macrophylla x
S. mahagoni
es
la caoba mas apropiada a ser plantada.
SEED SOURCE VARIATION IN PUERTO RICO AND
VIRGIN ISLANDS GROWN MAHOGANIES
by
T.
F. Geary, H.
Barres, and R. Ybarra-Coronado
Institute of Tropical Forestry, Rio
Piedras, Puerto Rico^/
INTRODUCTION AND METHODS
Seed
was
collected
from
natural
stands
of Honduras mahogany,
Swietenia macrophylla
King,
and
Pacific
mahogany,
Swietenia
humilis
Zucc.,
in
eighteen
areas
from
Mexico
through Panama
in
1964
and
1965
(Table
1,
Figure
1).
Mature
seed
pods
were
usually
obtained by
shooting them from
the
trees,
and
it was attempted to
collect
five pods from
each
of
sixteen
trees
of normal appearance
in
each
area.
In
collection HGA
the
seed had
fallen
and
was
collected
from
underneath
the mother
trees. The
collection
areas, mother
trees,
seed
pods,
and
season
of maximum
seed
ripeness
are
described
in Appendixes
I,
II,
and
III.
The
seeds were obtained
in two
trips approximately one year apart and the resulting two
seed
collections were sown
as separate experiments. The
first
trip covered the northern part
of
the
collection
area
(all
the
Mexico
seed
sources
and
one
of
S.
macrophylla
from
Guatemala)
and
the
second
trip
covered
the
southern
part.
Seedlings
were
produced
by
directly
sowing
soil-filled
polyethylene
bags.
The
seedlings
of
each
mother
tree
were
grouped
together
in
the
nursery
and
the groups were
distributed
in random
order
in
the
beds.
No
measurements
were
made
of
the
seedlings
from
the
northern
collection,
but
height, number of simple
leaves, and presence or absence of compound
leaves were recorded
for
the
five
tallest
seedlings
from
each
mother
tree
from
the
southern
collection
five
months
after sowing.
Approximately
seven-month
seedlings
of
the
nine
seed
sources
from
the
northern
collection were planted
at eleven locations in Puerto Rico and two
in
St.
Croix,
U.S.
Virgin
Islands (Table
2). The
locations
are ranked
in Table
2
in approximate
order
of decreasing
temperature and
increasing
rainfall,
so
that Coamo
is hot and very
dry,
and
Guilarte
cool
and
very
wet.
Added
to
the
plantings,
except
at
Estate
Jealousy,
were
seedlings
of West
Indies
mahogany,
Swietenia
mahagoni
Jacquin,
grown
from
seed
collected
in
St.
Croix,
where
this
species
has become
naturalized. The
initial plantings in
St. Croix were destroyed
by
error
and
were
replanted
ten months
later. The
eleven
locations
in
Puerto
Rico were
planted with approximately
seven-month
seedlings
of the
southern collection approximately
a
year
after
planting
the
northern
seedlings.
Usually
the
planting
areas
of
the
two
collections
were
side
by
side
within
locations,
although
occasionally
they
had
to
be
separated
because
of
terrain.
For
example,
at
Guajataca
in
the
limestone
hills
of
northwestern Puerto
Rico,
the two collections were planted
at the bottom of different
sink
holes. The
plantings
of the
southern collection included ten seed sources, but one has been
excluded from the report because
all of
its seedlings came from
a
single mother
tree.
—^
In
cooperation with
the
University
of Puerto Rico
1
The
planting
design was
the
same
at
each
location
for each
collection,
and
2.4
meter
square
spacing was used
throughout. The
basic
units were
single
tree plots arranged
into
3
plot
X
3
plot
square
blocks.
Nine
different
seed sources were planted
in each block. There
were 32
blocks
for each
collection
at each location and
these were
laid out
in
a 4 block x
8
block rectangle.
It was attempted to plant the same number of seedlings from each of
16
mother
trees
at
each
location.
However,
this was
not
possible
because
of
lack of seedlings
for some mother
trees,
less than
16 mother
trees of sources MHA and MPA, and
the 9
cell
instead
of
a
10
cell
block.
There was
a
considerable
difference among
seed
sources
in the
broadness
of
the
genetic
base
(Table
3).
At
one
extreme
source HMB was
represented
in
the
eleven
Puerto
Rico
field
plantings by only
7 mother
trees and
there was
large variation
in
the number of
seedlings planted from each of the
seven. One mother
tree alone was the
source
of 46% of the HMB
seedlings. At the other extreme the number of seedlings planted
from each mother tree of source HSA only ranged from 20 to
24.
The
Puerto
Rico
locations except Coamo were planted within
a period of
six weeks with
the
seedlings
from
the
northern
collection. Coamo
was
planted
six
weeks
later
than any
other.
All
Puerto
Rico
locations
were
planted
within
a
period
of
four weeks
with
the
southern
seedlings.
Most
of
the
plantings
occurred
in
the
months
of
November
and
December
of
1964 and
1965.
Seedlings
that
died
within
the
first
few months of planting
were
replaced
within
eight months
of the
initial planting (or the complete replanting
in
St.
Croix)
and
usually
within
four
months.
Five
percent
of
the
northern
seedlings
and
six
percent of the southern were replaced.
Field
measurements
have
been made
a number
of times since
planting.
Recorded were
survival,
height and
diameter
breast
height (DBH),
and whether
or not
trees were attacked
by
the mahogany
shoot
borer, Hypsipyla grandella
Zeller,
during
the preceding
year.
In
this
report
survival and growth
are
based on
measurements
made during
late March-early April
1971
in
Puerto
Rico
and
mid-February,
1971,
in
St.
Croix. The
trees
of northern
origin
were
then
in
their
seventh
year
of growth
(sixth
year
in
St. Croix) and
the southern
trees
were
in
their
sixth
year.
The
report
on
shoot
borer
is based
primarily on
data
recorded
during February
and March
of 1969, when
it was
still
possible
to
distinguish the
tip of the
leader.
Measurements
of
leaf
characteristics
were
also made
in
1969 on
a sub-sample
of
trees.
The
locations
in
Puerto
Rico were
stratified
into
three
size
classes
based on
height. From
each
stratum one location was selected
at random, and
at each location
five sample
trees of
each
seed
source were randomly
selected. From
each
tree one mature, undamaged
leaf was
selected
from
one
of
sixteen
crown
regions.
Measured
were
lengths
of
petioles,
rachises,
leaflets, and
petiolules;
leaflet length;
leaflet maximum width; and number of leaflets.
Statistical
analysis
of
field
survival
and
growth
posed
a
problem
because
of
the
non-orthogonal
field
design,
replantings,
missing
plots,
differences
in
measured
growth
intervals,
heterogeneity
of variances,
and
interactions.
Therefore,
for many comparisons, no
statistical
analyses of variance were made. Mean annual height increment was used
for many
comparisons
to
adjust
for
the
differences
in measurement
periods. On
subsets
of data on
which
analyses of variance were made
the
following was
done:
for
survival, transformation
to
arc
sin
values
and
two-way
anova;
for
height
and DBH,
multiple
regression
analysis
ignoring
differences
in
length
of the measurement periods; the
five percent confidence
level
was chosen
for establishing
statistical significance.
2
RESULTS
Seedling characteristics — southern collection
The
nine
southern
seed
: sources:
varied
in
seedling
height, number of simple
leaves and
number of compound
leaves
(Table
4). The superior height of seed sources MNB and MNA
was later to be found
in the
field plantings. Except for
this, nursery heights did not predict
future
field
results. The number
of simple
leaves on
a
seedling was independent of species
and
seedling
height, and there was no obvious relationship
to geographic
origin. The average
seed
source
of
S.
macrophylla
has
few
seedlings with compound
leaves
after
five months
growth
in
the
nursery and
those
of
S.
humilis had many.
However,
few
seedlings
of seed
source HGA had compound
leaves and
this resemblance
of HGA to typical
S. macrophylla
was found
in
subsequent
field
analyses. HCA showed an
intermediate
response
in
seedlings
with compound
leaves,
as
it often did
later in other characteristics.
Survival
in field plantings
A much greater percentage of S. macrophylla (M) trees survived than trees of S. humilis (H) and
S. mahagoni (WIM) when averaged over
all planting locations (Table
5.). However,
there was
a major
interaction
in species survival with moisture regime of the planting location. At the
drier
planting
locations,
survival of
S.
humilis and
S. mahagoni was greater than that of S.
macrophylla.
This difference on the
drier
sites was
statistically
significant
in the plantings of
the
southern
collection
only.
There was no difference
in
survival between
S.
humilis and
S.
mahagoni.
Within
a
species
there was
considerable variation
in
survival
associated
with
seed
source.
On
the
wetter
sites
there were
statistically
significant
differences among
seed sources of S.
macrophylla
of both
northern and
southern
collections,
and among
S.
humilis seed sources
of * the
southern,
but
not
northern
collection.
However,
on
drier
locations
the
only
significant
difference
among
seed
sources
within
a
species
was
that
of
S.
humilis
seed
sources
of
the
northern
collection.
The
most
outstanding
variation
associated
with
seed
source
was
that
of
seed
source HGA
which
survived
in
a
pattern
more
typical
of
S.
macrophylla
than
S.
humilis
(i.e.,
percentage
survival was
greater on
wetter than on
drier
locations), and that of HCA which survived equally well on both wet and dry
locations.
In
addition
to
the
distinction
in
survival between
wetter and
drier
locations,
there were
significant
differences
in
survival
among
locations within
the
two
moisture
classifications
(Table
6).
Very
low
survival
occurred
at
Estate
Jealousy,
where
there
were
maintenance
problems
in
addition to drought;
in the northern collection
at Guilarte, where road building
activity
caused
soil movement
over some
plots; in the southern collection
at Coamo, where
severe
drought
occurred
during
the
establishment
period; and among most
seed
sources
of
S.
humilis and
S.
mahagoni on many of the
wetter
sites,
especially
at the three
that were
probably
the
coolest and
wettest,
Maricao,
Matrullas,
and
Guilarte.
There was no
evidence
that
within
the
two
moisture
classifications
the
pattern
of
survival
of
any
individual
seed
source
from
location
to
location
differed from
that
of the
overall
species,
including
seed sources HGA and HCA.
3
Seven
locations
were
selected
for more
intensive
statistical
analyses
of
survival
on
the
basis
of
their
lack
of
establishment
problems,
presence
of both
collections,
and
climatic
suitability for mahogany
culture.
Seed sources of poor adaptability
(S. mahagoni and
all but
one
seed
source
of
S.
humilis)
at
these
locations
were
excluded.
There were
statistically
significant
differences
in
survival associated with seed source and planting location (Table
7).
But
in
general
survival
of
all
seed
sources and
at
all
planting
locations was
fair
to
good.
There was
little
difference
in
survival between
collections and
there was
a greater range
in
survival associated with planting locations than with seed source.
Shoot borer attack
As
of
January
1969,
four
and
three
years
respectively
after
planting
the
northern and
southern
collections,
shoot
borer
attacks
were
recorded
at
seven
locations
(Table
8).
Unattacked
were
the
two
St.
Croix
locations,
Guajataca,
and
the
three
coolest,
wettest
locations
in
Puerto
Rico.
Very
few
trees
were
attacked
at
Rio
Abajo,
while
attack was
heavy
at
Cambalache,
Tract
105,
and
El
Verde.
By
early
1971
all
but
Guajataca
and
Maricao
of
the
borer-free
locations
in
early
1969
were
being
attacked,
some
of them
heavily, and attack
at Rio Abajo had become heavy,
as shown below:
Shoot borer attack in late
1970-early 1971
in
previously unattacked locations
Location
Trees
atta
JEAL
73
THOM
96
RABA
71
MATR
20
GUIL
41
In
contrast
at Coamo,
Las
Marias,
and
Guavate,
almost no new
attacks were recorded
in
1970
and
1971,
while
at
Cambalache,
Tract
105,
and
El
Verde,
borer
attack
continued
heavily. Shoot borer attack
at the various locations could be
classified
as follows:
Extent of Shoot Borer Attack Problem
Serious
Minor
None
JEAL
COAM
GUAJ
THOM
LMAR
MARI
CAMB
GUAV
T105
MATR
RABA
EVER
GUIL
A
greater percentage
of
S.
macrophylla
trees were
attacked than
S.
humilis
trees, and
S.
mahagoni
showed
no
signs
of
attack
(Table
8).
There
was
no
evidence
of
geographical
variation
in
susceptibility to borer attack within
S.
macrophylla.
Within
S.
humilis HGA and
HCA,
again showing
characteristics
of
S.
macrophylla,
were
attacked more
than other seed
sources.
4
Growth in
field plantings
Height growth
followed
a
pattern
similar
to
survival.
Trees of S. macrophylla grew more
rapidly
in
height
than
trees of
S.
humilis and
S.
mahagoni (Table
9).
Again
there was an
interaction
with
moisture
regime
of
the
planting
location.
Trees
of
S.
macrophylla
grew
more
rapidly
on
wetter
sites
than
drier
sites,
while
trees
of
S.
humilis and
S.
mahagoni
grew
more
rapidly
on
drier
than
wetter
sites,
but
never more
rapidly
than
trees
of
S.
macrophylla
(ignoring
individual
seed
source
variations).
And
again HGA
and
to
some
extent, HCA,
exhibited
characteristics typical of S.
macrophylla.
There was no
difference
in
the
rate of growth between
S.
humilis and
S. mahagoni.
Growth
of
S.
macrophylla
was
poorest
at
the
driest (COAM)
and
the
three
coolest,
wettest
locations (MART, MATR,
GUIL),
and
of
the
remaining
locations
growth
of
.S'.
macrophylla was
best
at
the three (GUAJ, LMAR, GUAV) where shoot borer attack wasn’t
a
serious problem
(Table
10).
Statistical
analysis
of the
six
fastest growing seed sources
(all
S.
macrophylla
except
for HGA)
of each
collection on
the
seven
locations
in
Puerto Rico
with
the
best growth
revealed
statistically
significant differences associated with seed source
and
planting
location (Table
11).
The
few months
difference
in
the
measured
period
of
growth
between
locations
was
ignored
for
this
analysis.
Poorest
growth
in
the
northern
collection
was
that
of MMA
and MME,
although MME
did
relatively much
better
at
the
drier
location
(Table
9).
The
two
southern most
sources
of
S.
macrophylla
and
the
S,
humilis
source HGA
grew
poorest
within
the
southern
collection,
although on
drier
sites
they grew
relatively
better.
S. macrophylla of the southern collection has grown
faster than
that
of the northern collection, and seed sources MNB and MNA have grown outstandingly.
At
a moist
site with only minor shoot
borer
attack (LMAR),
these two seed sources grew
at
a
rate
of
1.75 meters
a year.
This superiority, however,
did not occur on the
drier
sites.
Best
height
growth
occurred
at
the
three
locations (LMAR, GUAV,
and GUAJ)
with
httle
or
no
borer
attack.
Although not
analyzed
statistically growth was
also good
at
the
two
St.
Croix
locations
(1.0
m/yr.). DBH
growth
fitted
in
the
pattern
of height growth
with
the
exception
of
the
northern
collection
at
El
Verde,
where DBH
growth
was
relatively
better
than
height,
no
doubt
reflecting
the
greater
impact
of
shoot
borer
on
height.
Leaf dimensions
The
leaves
of
S.
macrophylla
trees
had more
leaflets and
were
larger than
those
of
S.
humilis,
which
in turn were greater than those of S. mahagoni (Table
12). The numbers and
sizes
varied
with
seed
source
within
a
species,
but
there
were
no
obvious
geographical
patterns nor important differences except for seed source HGA and
to
a
lesser extent HCA.
These exhibited
characteristics typical of S. macrophylla instead of S.
humilis.
Planting
location had
a
greater
effect on
petiole
and
rachis length than seed
source. For
example,
location
variance
accounted
for 28%
of
the
total
variance
in
petiole
length
as
opposed
to 9%
for
seed
source variance.
However,
the
total
length
of the main
leaf
axis
(petiole
plus
rachis)
varied
little
from
location
to
location,
nor
did
leaflet number
and
leaflet dimensions.
5
DISCUSSION
Differences
exist among
seed
sources of Swietenia
in
seed pods (Appendix
III),
seedling
characteristics (Table 4).
suivival
after
field
planting (Table
5),
susceptibility
to shoot borer
attack
(Table
8),
growth
rate
(Table
9),
and
leaf
characteristics
(Table
12).
These
differences could
not
be
related
to
a
geographical
pattern, although
superficial examination
might
suggest
one.
For
example,
the
northernmost
seed
source
of
S.
macrophylla, MM A,
survived
and
grew
least
of
all
the
S.
macrophylla
seed
sources.
However,
in
addition
to
being
the
northernmost,
it
was
also
the
one
with
the
greatest
variation
in
plantable
seedhngs produced
per mother
tree
(Table
3),
and
the seed was collected
in an
area where
considerable dysgenic selection apparently had occurred (Appendix
I).
The
greatest
practical
differences
were
those
between
species
and
those
caused
by
planting
location,
the
latter
in
turn
influenced by
shoot borer
attack.
S.
macrophylla
has
grown
faster than
S.
humilis and
S. mahagoni on
all types of
sites, although the
latter two
are more
drought
resistant.
S,
macrophylla then
is the
species of choice
for planting within
most
of
the
Subtropical
Moist
and
Wet
Ecological
Life
Zones
of
Puerto
Rico.
In
Subtropical Dry and
in
the
transitional
area of the
Subtropical
Moist
Zone,
the hybrid,
S.
macrophylla
x
S.
mahagoni
should
be
planted
(Geary,
Nobles,
and
Briscoe,
1972).
It
has
yet
to be shown by
experimentation whether
the
hybrid should also
be preferred
in wetter
zones.
Mahoganies
do
not
seem
adapted
to
the
Subtropical Lower Montane Wet Zone
or
the
wettest
part
of the
Subtropical Wet
Zone,
nor
to
serpentine
soils,
the
soil type of the
Maricao location.
Shoot
borer
had
a
great
impact
on
mahogany
growth.
It
seems
certain
that
the
mahoganies
at
Tract
105,
El
Verde,
Cambalache,
and
Rio Abajo would
have been much
taller
if
they
had
not been
attacked. The
lack
of attack
at some
locations
is
difficult
to
explain.
Shade
on
the
trees
reportedly
protects
against
attack
(Marshall,
1939;
Tropical
Forest
Experiment
Station,
1953;
Grijpma
and
Gara,
1970),
and
the
mahoganies
at
Las
Marias,
Guavate, and Guajataca
did
have some
shade from surrounding
forest and poisoned
overstory
trees,
while
those
at
El Verde,
Cambalache,
and
Rio Abajo were
in open
fields.
However,
trees
at
Tract
105
also
had
some
shade
on
them.
Nevertheless
from
past
experience
with mahogany
culture
it
seems
safe
to
conclude
that
the
trees
at
El Verde,
Cambalache,
and
Rio Abajo were
severely
attacked
because
they were
in open
fields. The
low
incidence
of
attack
at
Matrullas,
Guilarte,
and
Maricao,
the
cessation
of
attack
at
Coamo,
and
the
lower
attack
incidence
of
S.
humilis
certainly were partially
related
to
poorer
tree growth,
since
the moth
stage
of the borer
is attracted
to
fresh foliage (Grijpma
and
Gara,
1970).
Climatic
effects
on
borer
activity
as
well
as some
shade may
also
have
contributed
to
the lower
incidence
at
the coolest,
wettest
locations. Tree growth
at Estates
Thomas and
Jealousy
did
not seem
affected by
shoot borer only because
these
attacks did
not occur
until
after
a
period of initial very rapid height growth.
In the years to come the
effect
should become more
evident. The
reason
for
the
delayed
attack
at
Estates Thomas
and
Jealousy,
where
the
plantings
are
in
open
fields, no
doubt
was
caused
by
adverse
climatological
factors and
initially low
levels of shoot
borer
population.
Only
S.
mahagoni
of
all the seed sources studied showed immunity
to
attack.
6
If
S.
macrophylla
is
to be planted, then where should the seed come from?
Selection of
collection
area
based
on
climate
as
a
criterion
might
be
rational.
There
was
an obvious
interaction
of
seed
source with moisture
regime
of the
planting
locations and
this
can be
more
or
less
related
to
the
length
of the dry
season (Appendix
I)
of the
seed
collection
areas.
The
fastest
growing
seed
sources (MNA
and MNB)
at
moist
and
wet
locations
originated
in
the
areas
with
the
shortest
dry
season,
and
the two
poorest
growers
at
the
same
locations
were
from
areas
with
the
longest
dry
season.
At
the
drier
locations
this
superiority
of MNA and MNB
did
not
exist.
S.
humilis
seed
source, HGA, came from
an
area with
the
shortest
dry
season
for
this species, and
this might explain
its better growth.
However,
there
are
obstacles
to
completely
accepting
this
argument.
Firstly,
seed
sources
MMA and MME came
from
areas with
a
lot
of dysgenic
selection.
Secondly,
on
the
drier
sites
shoot
borer
attack may
have
tended
to
keep
all
seed
sources
at uniform
height by
killing back new shoots of
all lengths.
Thirdly, records were not kept of seedling yield from
seed
sown,
or
the
percentage of seedlings used.
It
is possible that
at
least some of the seed
source
variation
could
be
due
to
different
selection
intensities
within
the
nursery (Geary
and
Barros,
1973).
Probably
the
most
important
question
is
whether
mahogany
plantations
should
be
established.
Experience
has shown
that weeds are
a serious problem
in mahogany culture
in
Puerto
Rico and
are
expensive
to
control.
Mahoganies maintain
a narrow crown
for many
years,
thus
not
suppressing
weeds;
and
in
moist and wet zones on
fertile
sites,
vines
are
continuously
suppressing
the
trees. On
well
cleaned
sites,
shoot
borers
often
ruin
the
tree
form
and
reduce
growth.
Therefore,
we
do
not
recommend
mahogany
plantations
be
established on
a
large
scale
in
Subtropical Moist and Wet Zones.
Individual landowners may
be
willing
to do the required weeding effort with small plantations on nutrient
rich
sites
to
grow
this
fine
quality
-cabinet
wood.
In
the
Subtropical
Dry
Life
Zone
and
into
the
transitional
area
of
the
Subtropical
Moist,
planting
of
hybrid
mahoganies
has
been
recommended, mainly
because
it
is
for
all
practical purposes
the only timber tree that can
be
recommended.
Growers
in
the
drier
areas
can
keep
brush around young
trees
to
cast
shade
on
the crowns
to
reduce
borer
attack and
later when crowns emerge
into
full
light,
prune
to
single
leaders
following
shoot
borer
attack.
In moist and wet
zones, landowners
have
a
choice
of
pines,
eucalypts,
and
teak,
among
other
species,
that
are
easier
and
cheaper to grow.
Priority
research
on
mahoganies
in
Puerto
Rico
and
the
Virgin
Islands
should
be
on
improving
cultural
techniques
to
reduce weeding
costs,
controlling
shoot borer, and
trying
the hybrid
in the moist and wet zones. More genecology would have
lesser priority.
ACKNOWLEDGMENTS
We thank
the
following
for
their
support:
Harvlan,
Inc.
for
land
at Estate Jealousy; Mr.
Jaime
Ensenat
for
land
in
Las
Marias;
Mr.
Jose
Ismael
Zayas
for
land
in Coamo;
the
Puerto
Rico
Office
of
Conservation
of
Forest
Resources
for
land
in
the
Cambalache,
Guajataca, Rio Abajo, Guavate, Maricao, Toro Negro (Matrullas), and Guilarte
State Forests;
and
Mr.
M. Antoni of the
University
of Puerto
Rico,
Agricultural Experiment
Station
for
statistical
assistance.
7
LITERATURE CITED
(1)
Geary,
T,
F. and de Barros,
N.
F.
1973.
Seed crop environment may influence progeny
tests.
Commonwealth Forestry Review
52:
(in press).
(2)
Geary,
T.
F., Nobles,
R. W., and
Briscoe,
C.
B.
1972.
Hybrid
mahogany
recommended
for
planting
in
the
Virgin
Islands.
USDA Forest
Service Research Paper ITF-15.
(3)
Grijpma,
P. and Gara,
R.
I.
1970.
Studies
on
the
shoot
borer
Hypsipyla
grandella
Zeller.
I.
Host
selection behavior.
Turrialba 20:233-240.
(4)
Holdridge,
L.
R.
1967.
Life zone ecology.
Tropical Science Center,
San Jose, Costa Rica. 206p,
(5)
Marshall,
R.
C.
1939.
Silviculture
of the
trees
of Trinidad
and Tobago. Oxford
Univ.
Press,
London. 240
p.
(6)
Tropical Forest Experiment
Station
1953.
Thirteenth annual report,
Carib.
Forester
14(1&2):13.
8
Figure
1.
Seed
collection
areas
in
Mexico
and
Central America,
codes
as
in Table
1.
Table
1. — Areas
in which
seeds
of
Su)ZcXG,yu,Ci species were collected .
Seed
Geographical
Coordinates^/
Area
No.
source
code
Species
collected
Country
North
latitude
West
longitude
Mother trees
(No.)
Collection
date
1
.
MMA
mac^opkytta
Mexico
20° 30’
97020
’
16
Jan.
1964
2
.
MMB
Tl
It
17°40'
94°55’
16
Feb
.
1964
3.
MMC
!?
II
16°55’
91°35’
16
Feb.
1964
4.
MMD
II
tl
18°25’
89°25’
16
Feb.
1964
5.
MME
11
II
19°30’
88°05’
16
Feb,
1964
6
.
MGA
II
Guatemala
17°00’
Q9°40’
16
Mar.
1964
7.
MHA
II
Honduras
15°50’
86
° 00
’
7
Apr.
1965
8
.
MNA
M
Nicaragua
13°40'
84°10’
16
Feb.
1965
9.
MNB
II
tl
11°50’
83°55’
16
Feb.
1965
10
.
MPA
It
Panama
7° 35’
80°40’
15
Dec.
1964
11
.
MPB
II
II
8°50’
78°00’
16
Dec.
1964
12
.
HMA
kumitUi
Mexico
18°05’
102°15’
16
Jan.
1964
13.
HMB
II
II
22
° 20
’
105° 20’
16
Jan .
1964
14.
HME
II
II
16°20’
94°00’
16
Feb.
1964
15.
HGA
II
Guatemala
14°15’
90°50’
16
Feb.
1965
16.
HSA
II
El Salvador
13°40’
88°55’
16
Feb.
1965
17.
HNA
M
Nicaragua
12
° 10
’
00 o^
0
0
16
Feb.
1965
18.
HGA
II
Costa Rica
10°40’
85°30’
16
Jan.
1965
a/
Estimated center of collection area to nearest
five minutes.
Table
2.—Description of planting locations.
Location
Code
Ecological
life
zone^/
Soil classification^/ and
series-^/
Elevation
(meters)
Coamo
COAM
STD
Typic or Udertic Arguistoll
Like
Coamo or Llanos
clay
250
Estate
Jealousy
(St.
Croix)
JEAL
STD
Udic Pellustert
Aguirre clay
40
Estate
Thomas
(St.
Croix)
THOM
STD
Typic Calciustoll
Fredensborg
clay
90
Cambalache
CAMB
STM
Tropeptic Eutrothox
Bayamon sandy clay loam
50
Guajataca
GUAJ
STM
Tropeptic Haplorthox
Coto
clay
230
Tract
105
T105
STM
Vertic Eutropept
Mucara silty
clay
500
Las Marias
LMAR
STW
35% Orthoxic and 80% Typic
Tropohumult
35% Daguey and 80% Humatas
clay
220
Rio Abajo
RABA
STW
Tropeptic Haplorthox
Catalina silty clay
330
El Verde
EVER
STW
Tropeptic Haplorthox
Comerio silty
clay
100
Guavate
GUAV
STW
Epiaquic Tropohumult
Los Guineos
clay
600
Maricao
MARI
STW
70% Typic Eutropept^/
70% Maresua silty
clay loam
730
Matrullas
MATR
STW
Epiaquic Tropohumult
Los Guineos
clay
750
Guilarte
GUIL
LMW
Epiaquic Tropohumult
Los
Guineos
clay
1050
(4)
a./
According
to Holdridge
.
STD=Subtropical Dry;
STM=Sub tropical Moist;
STW=Sub-
tropical Wet;
LMW=Sub tropical Lower Montane Wet.
W
By
the
7th Approximation of
a Comprehensive System of Soil Classification
of
the
International Society of Soil Science.
qJ
Soil series descriptions are available from the USDA Soil Conservation Service,
Fort Worth,
Texas.
60%
of
the northern sources planting was on
an oxisol yellower and
less
acid
than Nipe
clay.
Table
3.
Variation
in number
of seedlings planted
for
seed sources
and mother trees.
Seedlings
Coefficient
of
Seed
Mother trees
in
planted^"^
variation^/
Source
plantings
(no.)
(no
. )
{jQ
MMA
12
263
137
MMB
16
350
33
MMC
14
367
80
MMD
16
343
34
MME
16
361
10
MCA
16
347
17
MHA
7
254
99
MNA
16
350
14
MNB
16
335
43
MPA
15
349
7
MPB
16
351
12
HMA
14
357
80
HMB
7
156
123
HME
16
337
9
HGA
15
351
19
HSA
16
352
6
HNA
16
351
9
HCA
16
348
20
a/
Initial
field planting,
i.e.,
excludes
replacements.
W
Standard deviation of number of seedlings planted from each mother tree,
times
100,
and divided by
the average number
of seedlings planted per
mother
tree.
Table
4.— Characteristics
of
5-inonth-old seedlings
of nine
SLV^e,t2./lca seed sources
in
a Puerto Rico nursery.
Seed
Source
Height
( cm) 3l/
Simple leaves
per
tree
(no
. )^/
Seedlings with
compound leaves
(no.
out
of
5)
MHA
19.5
8.4
0.6
MNA
24.8
11.0
0.4
MNB
24.8
10.7
0.7
MPA
20.0
11.1
1.9
MPB
18.0
9.8
2.2
HGA
21.3
9.8
0.8
HSA
21.4
6.6
5.0
HNA
20.4
6.9
5.0
HCA
20.8
10.8
3.0
Mean of
five tallest seedlings
from each mother
tree.
Table
5.— Survival of
seed sources
in Puerto Rico
and
the Virgin Islands
as
influenced by moisture regime
of
the planting location.
Northern collection
Southern collection
Seed
All
13
9 wetter
4 drier
Seed
All
11
9 wetter
2
drier
source
locations
locations
locations
source
locations
locations
locations
% survival
% survival
MMA
65
73
48
MHA
82
89
50
MMB
72
80
53
MNA
80
88
40
MMC
64
71
48
MNB
76
87
26
MMD
72
77
60
MPA
66
72
37
MME
73
77
64
MPB
73
78
52
MGA
75
81
63
M mean
75
83
41
M mean
70
76
56
HGA
80
85
58
HMA
38
26
64
HSA
47
41
74
HMB
38
28
60
HNA
46
38
80
HME
Ai
11
74
HGA
21
71
77_
H mean
39
27
69
H mean
61
59
72
WIM
35
23
68
Table
6.—Variation in survival
of Sl^ZoXznZa species
from
location
to location in Puerto Rico and
the
Virgin Island^
Moisture
regime
Location
Northern collection
Southern collection
macAopkylZa
kmiUUM
Ynakaqoyii
macAopkylJici
humiZUi
% survival
Drier
COAM
52
76
84
16
52
JEAL
18
26
.
.
•
•
•
•
THOM
84
91
89
•
•
•
•
CAMS
70
71
70
66
92
Wetter
GUAJ
76
34
17
87
84
T105
85
18
8
87
48
LMAR
71
29
27
73
77
RABA
70
41
43
93
82
EVER
88
79
59
91
90
GUAV
92
26
26
88
62
MARI
78
9
14
68
18
MATR
72
0
4
72
33
GUIL
56
5
8
87
37
Table
7.— Statistically significant differences
in survival
among
selecT" StVyLCX2./U,CL seed sources
and planting
locations".
Variation among seed sources
Northern collection
Seed
Survival
source
%
Southern collection
Seed
Survival
source
%
MGA
84
a/
MMD
82
MME
82
MMB
80
MMA
72
MMC
72
HGA
93
MPB
89
MHA
88
MNA
85
MNB
81
MPA
75
Variation among planting locations
Northern collection
Planting
Survival
location
%
Southern collection
Planting
Survival
location
%
GUAV
92
EVER
88
T105
85
GUAJ
76
LMAR
71
CAMB
70
RABA
70
RABA
93
EVER
92
GUAJ
88
GUAV
88
T105
88
LMAR
76
CAMB
70
— Values not
connected by
a line are statistically different
at
the 5% confidence
level.
Table
8.
Shoot borer attack in field plantings
in early 1969
Northern collection
Southern collection
Planting
location
Trees
attacked
(%)
Seed
source
Trees
attacked
(%):a/
Seed
source
Trees
attacked
(%)a/
COAM
34
MMA
66
MHA
64
JEAL
0
MMB
68
MNA
64
THOM
0
MMC
63
MNB
73
GAME
91
MMD
65
MPA
60
GUAJ
0
MME
64
MPB
59
T105
74
MGA
64
M mean
64
LMAR
28
M mean
65
RABA
2
HGA
65
EVER
95
HMA
56
HSA
52
GUAV
37
HMB
42
HNA
45
MARI
0
HME
46
HGA
64
MATR
0
H mean
48
H mean
56
GUIL
0
WIM
0
a/
~ At
the six locations with most attack
Table
9.—Annual height growth
of five-to-six year old
ScVyC2XQ.yuxi seed sources
in Puerto
Rico and
the Virgin Islands
as
influenced by moisture regime
of
the planting locaClOh.
Northern. collection
Southern collection
Seed
source
All
13
locations
9 wetter
locations
4 drier
locations
Seed
source
All
11
locations
9 wetter
locations
2
drier
locations
meters /year
meters/year
MMA
0.79
0.82
0.74
MHA
1.00
1.05
0.78
MMB
0.88
0.94
0.77
MNA
1.05
1.13
0.70
MMC
0.87
0.89
0.83
MNB
1.14
1.24
0.66
MMD
0.88
0.89
0.86
MPA
0.82
0.83
0.74
MME
0.84
0.83
0.88
MPB
0.81
0.81
0.82
MGA
0.90
0.93
0.84
M mean
0.96
1.01
0.74
M mean
0.86
0.88
0.82
HGA
0.78
0.80
0.68
HMA
0.47
0.34
0.78
HSA
0.36
0.31
0.55
HMB
0.44
0.31
0.75
HNA
0.40
0.36
0.58
HME
0.40
0.23
0.77
HCA
0.62
0.60
0.67
H mean
0.44
0.30
0.76
H mean
0.54
0.52
0.62
WIM
0.45
0.34
0.71
Table 10.-—Annual height growth of
SiA)^QXQ,yilcL species
on Puerto Rico and Virgin Islands planting locations.
Planting
SiAiCztzyiCci
SwX,eXQ,nla
location
mcLCAopkytta
kumlLU
makagoyii
meters /year
COAM
0.48
0.41
0.44
JEAL
1.04
0.96
•
•
•
•
THOM
0.96
0.88
0.79
CAME
0.89
0.82
0.58
GUAJ
1.33
0.47
0.18
T105
1.01
0.40
0.22
LMAR
1.41
0.73
0.25
RABA
0.81
0.62
0.35
EVER
0.82
0.52
0.56
GUAV
1.27
0.52
0.56
MARI
0.67
0.13
0.21
MATR
0.53
0.17
0.29
GUIL
0.63
0.28
0.46
Table
11.
Height
of
the fastest growing
f ive-to-six-years-old seed
sources
of
Sw^eX£,yu.a on the best
sites
in Puerto Rico.
Height growth
DBH growth
Seed source
Height
Seed source
DBH
Comparison
or location
(meters)
or location
(cm)
Northern seed sources^/
MMB
MCA
MMD
MMC
MME
MMA
Southern seed sources^/
MNB
MNA
MHA
MPB
HGA
MPA
Locations
over
northern sources^/
LMAR
GUAV
GUAJ
T105
EVER
CAMB
RABA
Locations over
southern sources^/
LMAR
GUAJ
GUAV
T105
CAMB
RABA
EVER
6 .
6
£/
MMB
8.2
6 .
6
MGA
7.4
6.4
MMC
7.3
6.3
MMD
7.2
6.1
MMA
6.8
5.7
MME
6.
6
7.4
MNB
7.1
6.9
MNA
6.8
6.3
MHA
6.8
5.5
HGA
6.7
5.4
MPA
5.6
5.3
MPB
5.5
o
•
00
GUAV
8.5
7.9
LMAR
8.3
7.3
EVER
7.6
5.9
T105
7.0
5.2
GUAJ
6.8
5.1
CAMB
6.7
4.6
RABA
5.9
8.6
LMAR
8.7
7.8
GUAJ
6.
6
6 .
6
GUAV
6. 6
5.5
CAMB
6.3
5.4
RABA
6.1
5.0
T105
5.4
4.0
EVER
5.3
Approximately six years after planting,
b/
Approximately five years
after planting.
_c/
Values not connected by
a line are statistically different
at
the 5%
confidence
level.
Table
12.—Leaflet numbers
and
leaf dimensions
of
seed sources
Seed
Leaflets
Petiole
Rachis
Petiolule
Leaflet
Leaflet
source
(no.)
length (cm)
length (cm)
length (cm)
length (cm)
width (cm)
MMA
11.3
14
30
0.52
19
6.5
MMB
12.4
20
31
0.62
20
7.3
MMC
11.0
20
29
0.70
19
7.1
MMD
11.4
15
24
0.50
17
5.9
MME
10.8
15
24
0.48
16
6.1
MGA
11.3
19
21
0.56
17
6.1
MHA
10.5
18
26
0.52
19
6 . 6
MNA
11.1
18
27
0.42
17
5.8
MNB
10.3
16
27
0.52
19
6.5
MPA
9.4
14
22
0.58
15
5.9
MPB
11.3
19
24
0.61
15
6.1
M mean
11.0
17
26
0.55
18
6.3
HMA
CO
0
11
16
0.27
10
4.2
HMB
9.3
11
16
0.10
11
4.6
HME
10.4
10
14
0.19
10
4.0
HGA
10.5
20
28
0.80
18
6.8
HNA
9.9
12
17
0.24
11
4.2
HSA
9.4
13
13
0.16
11
4.2
HGA
12.1
11
23
0.29
13
5.0
H mean
10.2
13
18
0.29
12
4.7
WIM
9.7
5
8
0.27
5
2.1
Location^/
GUAJ
11.4
12
26
0.46
15
5.8
LMAR
11.2
21
18
0.47
16
5.5
MARI
9.4
13
30
0.42
18
5.8
a/
S.
mahagoyii
(WIM)
excluded
Appendix
I.—Description of
the collection areas.
seed
source
from
Dry Season
to
Months
(No.)
Altitude
(meters)
Topography
Exploitation
Extent
of
remaining
mahogany—/
>IMA
Nov.
May
7
25
Flat
Some
to much^/
NN
1MB
Jan.
May
5
90
Flat
None evident
M
IMC
Feb
April
3
640
Mountainous^/
None evident
VH
IMD
Dec.
May
6
110
Flat
Some
M
iME
Sept.
Jan.
Twice cut
to
and May
June
7
30
Flat
diameter limit
M
IGA
Feb.
May
4
120
to
300
Hilly
none evident
H
IHA
April
June
3
35
Mountainous^/
None evident
L
INA
mid
Feb.
mid April
2
0
to
30
Flat
None evident
M
INB
March
April
2
15
Flat
Some
to much
M
IPA
mid Dec.
April
4
1/2
380
to
710
Mount ainousk/
None to evident
M
IPB
Jan.
mid April
3
1/2
60
HillyW
None
to evident
M^/
iMA
Dec.
May
6
150
to
210
HillyW
None
to evident
NN
IMB
Nov.
June
8
30
to
90
Mountainous^/^/
None
to evident
NN
IHE
April
Sept.
6
180
to
210
HillyW
Much
NN
fGA
Dec.
April
5
45
Flat
Some
L
iSA
Nov.
April
6
460
to
610
HillyW
Much
NN
^A
Nov.
^pril
6
150
Hilly
Much
NN
ICA
Nov.
May
7
90
Flat
Much
a/ Trees found
at bottom of
slopes,
b/ Trees
found on slopes.
£/ Collection trees
founc!
in 0.5
acre area left after logging.
VH= very heavy,
H= heavy, M= medium,
L= light, NN= next
to none.
e!
In the Chucunaque Indian Reservation; NN outside the reservation.
Appendix
II.—Description
of
the mother trees
Seed
source
Height
(meters)
Diameter breast height
(cm)
Height
to
first
branch
(m)
Height
of
buttresses
(m)
Mean
Rang!e
Mean
Range
MMA
21
15
-
23
55
35
-
90
9
0.8
MMB
20
12
-
26
55
20
-
85
8
0.6
MMC
49
35
-
57
180
130
-
260
20
2.1
MMD
22
14
-
30
80
60
-
140
10
0.9
MME
19
15
-
24
70
40
-
145
10
0.8
MGA
30
26
-
39
90
55
-
115
15
1.3
MHA
40
34
-
52
no
75
-
130
19
2.0
MNA
39
34
-
44
75
50
-
130
17
1.2
MNB
30
24
-
34
65
55
-
80
15
1.4
MPA
31
24
-
40
90
65
-
130
17
1.2
MPB
30
24
-
37
130
55
-
200
16
2.6
HMA
12
8
-
16
45
25
-
90
4
0.0
HMB
11
6
-
15
35
15
-
60
3
0.0
HME
9
8
-
14
35
20
-
85
3
0.0
HGA
16
11
-
22
65
25
-
100
8
0.5
HSA
9
8
-
11
20
15
-
30
3
0.0
HNA
10
8
-
14
h-5
15
-
60
3
0.0
HGA
14
9
19
55
25
100
4
0.3
Appendix
III.—Description
of
the seed pods and months
of
maximum seed ripeness.
Seed
source
Pods
measured
(No.)
Length
(cm)
Diameter
(cm)
Rates
of
length
to
diameter
Months
of maximum
seed ripeness
MMA
64
14.1
9.2
1.55
February
MMB
64
15.5
10.0
1.55
February
MMC
64
14.6
8.6
1.70
February
MMD
64
12.6
8.2
1.55
February
MME
64
12.6
8.5
1.50
February
MGA
64
14.2
8.9
1.60
late Feb., mid March
MHA
8
14.0
7.6
1.85
early February
MNA
62
13.7
7.9
1.75
February
MNB
58
13.0
7.5
1.75
February
MPA
51
14.1
8.2
1.70
December
MPB
58
14.8
8.9
1.65
mid November
HMA
64
11.8
7.9
1.50
late January
HMB
63
14.0
9.0
1.55
February
HME
42
12.6
9.4
1.35
late Dec.
,
Jan.
HGA
0
.
.
.
•
•
•
•
•
•
January
HSA
53
13.3
8.7
1.55
early February
HNA
42
13.4
9.6
1.40
J anuary
HCA
55
12.8
8.6
1.50
mid Jan.,
early Feb.
T