Transplanting Tree Ferns to Promote Their Conservation in Mexico

2009·6.8 MB·English

by  Ana Alice Eleutério

Transplanting Tree Ferns Promote Their
to
Mexico
Conservation
in
Diego
PfiREz-SALiCRUP
Biologicas, Universidad Nacional Autonoma de Me)
s
CP
Xangari, 58089, Morelia, Michoacan, Mexico
Disregarding law prohibitions, artisans in the region of Cuetzalan, Mexico
harvest the stems of aduh tree ferns of at least two species, Cyathea divergens
tuerckheimii R.M. Tryon, and M. Martens produce
var. C. fulva et Galeotti, to
and Both
handicrafts (Eleuterio Perez-Salicrup, 2006). species are listed in the
Mexican law as threatened by land-use and land-cover changes (SEMARNAT,
2000).
Adult tree ferns are mostly harvested from natural populations that occur in
remnants montane These among most
of tropical forests. forests are the
PO
* Corresponding author current address: Department of Botany, University of Florida, Box
FL USA;
118526, Gainesville, 32611, e-mail: [email protected]
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endangered
ecosystems Mexico
in (Diario Oficial de Federacion, Luna
la 2001;
As
et al, 2001). a result, harvest contributes increased and
to mortality rates
jeopardizes the future regeneration of native
tree ferns in forests that are
already vulnerable and
(Eleuterio Perez-Salicrup,
2006).
Although
tree fern species are often restricted to shaded and high moisture
sites, at least three Cyathea and one Alsophila species commonly and
establish
grow
in ruderal such
habitats, as roadsides, near Cuetzalan
(pers. obs.).
any management
Therefore, policy aiming
preserve
to tree fern species in this
must
region consider occurrence
their in different habitats (Werth and
Cousens, from
remnants
1990), forest to disturbed areas. However, no study
has documented
yet the establishment requirements
of tree fern species in
this
region. Moreover, few studies have looked management requirements
at for
conserving the 13 Cyathea spp. that are currently considered endangered by
Mexican law
the (Diario Oficial de Federacion, Bernabe
la 2001;
et 1999).
al.,
Our
study focused on
providing
basic information allow the ex
to situ
conservation endangered
of species of the family Cyatheaceae. Tree
ferns are
usually propagated ex through
situ spores, vegetative tissues Finnie and
(e.g.,
Staden, Suzuki and
1987; et al. 2005), occasionally, by planting fronds
(e.g.,
Cibotium splendens
(Gaudich.) Krajina ex Skottsb.; Hensley, 1997) or the
apical meristems of harvested adults Dicksonia
(e.g., antarctica LabilL;
Foresfry Commission, Although
2001). not evaluated for the tree fern species
occur
that in the region of Cuetzalan, transplantation of seedlings and young
commonly
plants performed promote ex and
is to conservation
situ in situ
enrichment
planting endangered
of species (Primack, Transplants
2002). are
more
when
likely successfully and grow
to establish environmental
conditions
where
of the sites they naturally occur are similar to the ones of the areas they
and
are relocated Hayes, Montalvo and
to (Jones 1999;
Ellstrand, 2001).
For
the species Cyatheaceae
of native to the region of Cuetzalan,
transplantation from roadsides to safe sites could be an important strategy
for ex situ conservation. Along these roadsides, young tree fern sporophytes (<
cm
50 normally experience high due
tall) mortality rates to annual cutting of
A
herbaceous
vegetation road maintenance bank
for
(pers. obs.). of sporo-
phytes could be by them
created transplanting from exposed
protected
to areas
under
adequate environmental
conditions.
tree fern transplantation proves
If
and
successful, cost time associated with spore or gametophyte germination
The
could be avoided. young
sale of tree ferns for horticultural purposes could
income
potentially substitute obtained by
for selling handicrafts fashioned
from
tree fern adventitious and consequently
roots, contribute
to their in situ
To
evaluate the feasibility of using transplants of Cyathea and Alsophila
spp., extracted from roadsides for ex conservation, we documented
situ
first
the tree fern species that naturally established along margins
the of a major
We
road used
to access the city of Cuetzalan. then transplanted young
free
ferns to sites subjected to different light conditions to compare their survival
and growth among
rates species and Based on we
treatments. these
data,
provide
basic guidelines
for tree fern conservation in the study region.
MANAGEMENT
ELEUTfiRIO & PfiREZ-SALICRUP: OF TREE FERNS IN MEXICO
Species
Cyatheafulva
Cyathea
costaricensis
Methods
Study site.—This study was conducted in the vicinities of the city of
N-97
Cuetzalan (20° 01' 33" 31' 37" W), in the northern region of the state of
Puebla, central-eastern Mexico. Study areas were located elevations ranging
at
from 500 to 1470 meters above sea level (m.a.s.L). Annual precipitation
mm
mm, >
Mean
averages 4141 with months receiving 100 of
all rainfall.
annual temperature 19.4°C, ranging from 14.3°C in January, to 22.9°C in June
is
(Institute Mexicano de Tecnologia del Agua, 2000). The landscape
is
dominated by shade with
coffee plantations diversified overstory
tree
and montane
canopies, remnants.
tropical forest
Study species.—Three species of the genus Cyathea and one species of the
m
genus Alsophila were found along roadsides in a 670-1420 altitudinal
range: C. divergens var. tuerckheimii, C. fulva, C. costaricencis (Mett. ex Kuhn)
Domin. (Mickel and Beitel, 1988), and Alsophila firma (Baker) D.S. Conant
(Mickel and Smith, 2004). All species are protected by Mexican law (Diario
de
Oficial la Federacion, 2001).
cm
Cyathea spp. typically have trunks that range from approximately 10
cm
diameter at breast height (DBH) to approximately 130 with the mantle of
may
Stems and and
adventitious roots. stipes are scaly, stipes present spines
(Mickel and Beitel, 1998). Adult stems are occasionally bent due to mechanical
damage and
to the posterior recovery of vertical growth (Seller, 1981). Adults
m
may
of both C. divergens var. tuerckheimii and fulva present 12 stems
C. tall
and grow between 450-2400 and 800-2700
in sites m.a.s.L, respectively.
m
may
Cyathea grow
costaricencis to 8 in relatively drier environments
tall
usually located between 250 and 750 m.a.s.L (Table Mickel and
Beitel,
1;
1998).
Species of the genus Alsophila also present scaled stems and stipes, but
have Most
petiole scales characteristic apical setae (Korall et 2007). species
al.
grow between 1000 and 2000
m.a.s.L of elevation, rarely occurring at altitudes
m
below 250 m.a.s.L Adults of A. firma grow up to 10.5 and are typically
tall,
encountered between 750 and 2000 m.a.s.L (Table Stems may branch by
1).
adventitious buds (Mickel and Smith, 2004; Tryon and Tryon,
1982).
—
We
Abundance
of tree ferns along roadsides. counted, identified and
m
measured the height of all tree ferns taller than 0.5 growing within distances
m
< km
from pavement main highway
2 the along 16 of the to access the city of
AMERICAN FERN VOLUME NUMBER
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Cuetzalan. This highway
connects
the region to the state's capital city, Puebla.
We
assigned each
identified tree fern to the following five height categories:
>
0.5-1.0, 1.1-2.0, 2.1-3.0, 3.1-4.0, and 4.0 m. In addition, we divided the
tree
encountered
ferns along
the roadsides into three altitudinal ranges: 670-920
We
921-1170
and 1171-1420
m.a.s.l., m.a.s.L, only sampled
m.a.s.l. tree ferns
m
above we
0.5 in height because were
interested in quantifying the
abundance
of individuals had
that successfully established along
roadsides.
Experimental we
transplants.~ln October
2003, collected
tree ferns of the
two
number
species that presented a high of individuals with stem
a height
between 10 and 50 cm, encountered within 700-950
a ahitudinal
m.a.s.l.
range. Thirty C. divergens and 30 A. firma plants ranging 17-50 cm were
tall
excavated with spades from roadsides. Tree ferns were extracted with
their
entire root systems and approximately 1000 cm^
of local Plants within
soil.
this altitudinal range were minimize
selected environmental
to heterogeneity
between
the site they were extracted from and the ones they were transplanted
which
were
located 700
to, at m.a.s.l.
Fifteen transplants each were 50%
of species planted
into a shade
greenhouse, and were
fifteen planted in an open sun exposure) garden.
(full
Plants were transplanted within two hours 20-30 cm
into holes diameter and
cm
30 depth. Holes were with mixed We
filled local soil with organic compost.
We
cut fronds with expanded
all fully pinnae minimize
to transpiration.
marked
fiddleheads emerging
all (i.e., leaves] at the beginning of the
experiment and
in subsequent censuses. To evaluate growth we
rates
measured
stem
height (to the nearest 0.5 mm), from the base of the newest
crosier the monitored
to soil surface, frond production every months
2.5 for yr
1
(from October 2003 November and mean ±
to 2004), reported values SE
the
for
>
10%
study period. Fronds with green were considered
tissue alive {sensu
Durand and
Goldstein,
2001).
To
investigate the mortality of tree ferns along roadsides, in March 2003 we
< C
randomly cm
selected 60 tree ferns 30 of each divergens and
tall C. fulva,
two
the species that presented a higher number of individuals in
this size
growing
category, in altitudes ranging from 900 and 1200
This
m.a.s.l.
was
altitudinal range selected to include the extension of roadsides that would
be weeded we
during the period performed our To
study. verify the effect of the
we
transplantation procedure, used spade
a to extract half of the plants of each
We
with
species
their entire root systems. subsequently replanted each
plant
same
into the spot they had been extracted from (henceforth called transplanted
We
control individuals). measured stem heights before transplanting, and cut
all
mature fronds with fully expanded pinnae reduce water We monitored
to
loss.
plant survival for both transplanted control individuals and non-transplanted
mo
March
individuals, every from 2003-April
3 2004.
We
used
time compare
failure analyses to survival between and
rates species
We
between
treatments in both experiments (Fox, 2001). performed Cox
proportional hazard model and and Thompson,
log-rank tests (Pyke 1986) with
We
SPlus
6.0 (Insightftil Corp. Seattle, USA). used linear and quadratic
regressions between the initial and final stem heights to determine the model
MANAGEMENT
ELEUTERIO & PEREZ-SALICRUP: OF TREE FERNS MEXICO
IN
divergens
C. C. fulva A. firma C. costaricensis
Species
that best the patterns of stem growth (Sokal and Rohlf, 1995). and
fit Initial
stem were and we
final heights linearly related, therefore performed a Pearson
correlation analysis to evaluate the relationship between stems height
initial
We
and number
total of fronds produced. compared growth and frond
ANOVA
production between and two way
species treatments using a without
—
Abundance
of tree ferns along roadsides. Cyathea divergens and
C.
costaricensis were the most abundant tree fern species sampled along
roadsides, with 96 and 34 individuals, respectively. Both species were
represented in all height categories (Fig. Only twelve plants of C. fulva
1).
> cm
and Few
four of A. firma 50 were encountered within the sampled
area.
m
plants taller than 3 of both species were recorded Cyathea divergens
(Fig.
1).
was abundant whole
along the altitudinal range sampled, while the 34
all
plants of C. costaricensis were sampled within altitudes between 670 and
m
920 (Fig. Less than 10 individuals of fulva and A. firma were sampled
2). C.
whole was
in the study A. firma between 921-
area. restricted to altitudes
1170 m, while C. fulva was only recorded in the other two altitudinal ranges.
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50
divergens
C. C. fulva A. firma C. costaricensis
Species
analyses—
Survival While divergens experienced and 86.7%
C. 73.3 survival,
40%
A. firma experienced 93.3 and survival yr open canopy and 50%
after in
1
shade, respectively. Survival curves did not between
differ species log
(Fig.
3;
/
= = P > - =
rank, 1.2, df 1, 0.25) or light treatments (Fig. 3; log rank, 3.2, df
P > =
1, 0.05). Survival rates were not affected by the initial height of stems (z
P > - P > = P >
-1.18, species
0.2), (z 1.58, 0.10), or light treatment (z -1.81,
= = F >
0.05) (likelihood ratio test 6.58, df 3, 0.05). Tree ferns of C. divergens
transplanted whether open shaded more
to safe sites, or areas, survived than
those on roadsides and and
left (control transplant control; see Figs. 3 Less
4).
50%
than of the transplants of both C. divergens and C. fulva survived for more
mo
when
than
6 left along the roadsides. After yr from the beginning of the
1
37%
experiment, approximately
of the control individuals
of fulva survived,
C.
10%
while
than
less of C. divergens, or of the plants assigned to the other
treatments, survived had
(Fig. In general, plants kept as controls greater
4).
survival than the controls for the transplantation method.
mm/mo
Growth analyses.— Stem growth was between 4-5
in height
either in
the sun or shade treatments and for both studied species in the months
first after
Frond was
transplantation. production lower in the three months than
first
subsequent months
(approximately fronds/mo, comparison
0.6 in to the 1.0-1.2
fronds/mo we
observed during the subsequent For
period). these reasons,
decided to use data from the whole censused period stem
to calculate total
growth and Mean
frond production. height growth divergens were
rates for C.
mm/mo mm/mo
8.0 ± 1.0 in open canopy, and 13 ± 2.1 in 50% shade. Mean
mm/mo
±
height growth rates for yi./irma were 2.0 1.4 in open canopy and 6.0 ±
mm/mo
50%
0.8 in shade. Height growth were higher divergens than
rates for C.
ANOVA, = P <
for A. firma (Fig. 5(A); 23.0, 0.001), and were higher under
Fi,4i
shade than sunny ANOVA, = P <
in conditions
(Fig. 5(A); 9.0, 0.001).
^1,4^
Frond production was not related to initial stem height divergens:
(C.
< P > < P >
Pearson, shade and sunny
r 0.65, 0.5 in r 0.5, 0.5 in conditions; A.
< P > = P >
firma: Pearson, r 0.6, 0.25 in shade and r 0.295, 0.95 in sunny
conditions). Consequently, this variable was not considered as a covariate in
comparisons between and
the species treatments. Individuals of divergens
C.
produced 13.9 ± 0.85 and 15.5 ± 0.89 fronds/yr open canopy and 50%
in
±
shade, respectively, while A. firma individuals produced 6.8 0.97 and 10.4
± 50%
open canopy and
0.53 fronds/yr in shade, respectively. Cyathea
ANOVA,
divergens produced more fronds per yr than A. firma
(Fig. 5(B);
^1,35
= P <
50%
47.5, 0.001). Both species produced more fronds under shade than
open canopy ANOVA, = P <
in
(Fig. 5(B); F1.35 7.8, 0.001).
Cyathea divergens was the most abundant tree fern species found along
roadsides near Cuetzalan. This might from higher abundance
result a of the
AMERICAN FERN VOLUME NUMBER
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species in the region, together with an adaptation environmental
to conditions
m
we
in disturbed areas. In contrast, encountered only young individuals (<
1.0
stem
in height) of A. firma, all located within an intermediate altitudinal range.
Apparently, the conditions experienced disturbed
in areas are not appropriate
and
for the establishment long term survival of this species. All studied species,
except were unevenly
divergens,
C. distributed across altitudinal ranges. Air
humidity and
temperature, soil moisture content, and other environmental
may
conditions that vary with elevation restrict the habitat range of the less
adaptable This abundance and
species. distinct species' the variation in the
number
sampled
of tree ferns in each altitudinal range have be considered
to for
proper
selecting sites for extracting seedlings or transplanting them. In addition,
abundances and
species' in natural populations in a broader range of disturbed
areas should be assessed order provide management and
in to reliable
conservation
strategies for tree ferns in the area.
A
number when
higher
of transplants of divergens survived planted
C. in
safe sites, whether they were located in sunny or shade conditions, compared
to the controls along roadsides and such
left (see Figs. 3 4). In sites, tree ferns
recurrently suffer damage due weeding. Damage may have young
to stressed

AMERICAN
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(200
beyond
tree ferns
their capability
to recover, causing
their death. Although
n(
statistically
significant, survival
rates of C. fulva were higher
in control than
i
control transplant
treatments
after Tree may
1 yr. ferns of this species
nc
m.^rnnrmo
.t....
tV.o
-"used by
transplantation. Further
studies are necessary
t
the adequate
condition
3
of
C. fulva. In general, survival were when
rates
greater
tree ferns
.....
transplanted
to safe However, because
sites. our experiments do
not allow
for
comparisons among
sites for species other than
more
C. divergens,
solid
information
about
the
survival
of transplants depend
will on
future
experiments, which
in each
species
subjected
is to treatments.
all
Survival were
rates
statistically similar
for tree ferns relocated
to safe
sites
under sunny
shade
or
conditions. Bernabe
et al. [1999) observed the same
pattern two
for of the three
tree fern species they studied in montane
tropical
forests of Mexico. As
suggested by
these authors,
tree fern species vary
in their
tolerance
to different light conditions. In our study, both divergens and A
C.
firma seemed
to tolerate a wide range
of However
light availability.
the
survival
rate for A. firma planted in the shade was
higher, although not
statistically significant, than in the sun treatment. The
branch by
ability to
may
adventitious buds
confer
this species higher
a tolerance
to the stress
caused by
transplantation. For
A. shade
firma, conditions, which
in water
may
stress diminished,
is be
ideal
for transplantation,
during
at least
establishment,
until the transplants produce
expanded
their
first leaves.
Further
differences
in survival could have been
observed younger and
if
more
therefore,
vulnerable, transplants were used, and we had
if a bigger
sample
size or our observations were
prolonged more
than
for
1 yr.
Several on
studies
have
tree ferns focused on
understanding
the
plasticity of
phenological many
responses
of and
species
the such
effects of on
plasticity
population dynamics
Hunt
(e.g.. et 2002; Mehltreter and
al., Garcfa-Franco,
2008). Adaptations
to different light conditions have
particularly been
addressed
for several species
(Arens, 2001; Ash, 1987; Bernabe
et al 1999-
Seller, 1981, 1984; Walker and
Aplet, sunny
1994). In
conditions,
for example,'
several Cyathea
species grow
often
faster in height, produce more fronds and
reproduce
start to earlier than shady
in conditions
(Arens, 2001; Ash, 1987;
and
Bittner
Breckle, 1995; Poulsen and On
Nielsen, 1995). the other hand
Dicksonia
antarctica
Labil grow
slower sunny when
in
sites,
compared
to less exposed and more humid
where
they
sites, are less likely
t
experience
water
(Hunt
stress
et 2002). Different
al., light intensities can also
cause changes crown
in some
architecture of Cyathea
species (Arens and
Sanchez-Baracaldo, Cox
and
2000; Tomlinson,
1985; Tanner,
1983).
our
In study,
transplants of both divergens and
C. A. firma placed
in the
shade grew
and
faster in height produced more
fronds than those planted
in
sunny
Our
sites. data is in contrast to what has been observed
for other
tree
which
fern species, grow when
exposed
faster conditions
to of higher
light
availability (see Arens, 2001; Arens and
Sanchez-Baracaldo,
Ash,
1998;
1987;
and
Bittner
Breckle, 1995; Bernabe
et 1999; These may
al., Seller, 1981). results
reflect a faster adaptation of transplants shade When
to conditions.
planted
in