Altitudinal Zonation of Pteridophytes on Mt. Banahaw de Lucban, Luzon Island, Philippines

Abstract

Five altitudinal pteridophyte zones are established along the northeastern altitudinal slopes of Mt. Banahaw de Lucban, Quezon, Luzon Is., Philippines using cluster- and ordination analyses, namely: Zone 1, Cyathea contaminans – Dicranopteris–Nephrolepis–Diplazium patches at 700–800 m a.s.l.; Zone 2, Sphaerostephanos hirsutus var. hirsutus – Selaginella delicatula patches at 750–900 m a.s.l.; Zone 3, Cyathea philippinensis – Selaginella patches at 900–1200 m a.s.l.; Zone 4, Cyathea philippinensis – Cyathea callosa–Asplenium cymbifolium–Selaginella cumingiana patches at 1200–1550 m a.s.l. and; Zone 5 which is further divided into Sub-zone 5A, Cyathea callosa – Cyathea loheri-Hymenophyllaceae patches at 1550–1800 m a.s.l. and Sub-zone 5B, Cyathea loheri – Cephalomanes apiifolia patches at 1800–1875 m a.s.l. These pteridophyte zones coincide with the woody species zones of Mt. Banahaw de Lucban but differ significantly with the altitudinal fern zones of Mt. Makiling. Stepwise multiple regression analysis reveals that altitude exhibits a linear relationship with pteridophyte species distribution. Altitude and soil pH influence 65% of the variation in principal component 1 [PC1 = 0.0839 + 0.0010(altitude) − 0.2072(soil pH); r = 0.8058] and 27% of the variation in principal component 2 [PC2 = 2.0453 − 0.0005(altitude) − 0.2560(soil pH); r = 0.5206]. Thirty-three (33) species are preferential to specific microenvironments along the altitudinal gradient, making them effective altitudinal zone markers and biodiversity conservation indicators for the forest ecosystem of Mt. Banahaw de Lucban.

Full text

-1
Altitudinal zonation of pteridophytes on Mt. Banahaw de Lucban, Luzon
Island, Philippines
M.C.N. Banaticla
1
and I.E. Buot Jr.
2
1
Institute of Biological Sciences, Graduate School, University of the Philippines Los Ban
˜os (UPLB), 4031
College, Laguna, Philippines;
2
Institute of Biological Sciences, Graduate School, University of the Philippines
Los Ban
˜os (UPLB), 4031 College, Laguna, Philippines; *Author for correspondence (e-mail:
MCNBanaticla@hotmail.com)
Received 19 August 2003; accepted in revised form 9 August 2004
Key words: Altitudinal gradient, Altitudinal zonation, Ferns and fern allies, Mt. Banahaw de Lucban,
Pteridophytes, Tropical mountain
Abstract
Five altitudinal pteridophyte zones are established along the northeastern altitudinal slopes of Mt.
Banahaw de Lucban, Quezon, Luzon Is., Philippines using cluster- and ordination analyses, namely: Zone
1, Cyathea contaminans – Dicranopteris–Nephrolepis–Diplazium patches at 700–800 m a.s.l.; Zone 2, Sph-
aerostephanos hirsutus var. hirsutus – Selaginella delicatula patches at 750–900 m a.s.l.; Zone 3, Cyathea
philippinensis – Selaginella patches at 900–1200 m a.s.l.; Zone 4, Cyathea philippinensis – Cyathea callosa–
Asplenium cymbifolium–Selaginella cumingiana patches at 1200–1550 m a.s.l. and; Zone 5 which is further
divided into Sub-zone 5A, Cyathea callosa – Cyathea loheri-Hymenophyllaceae patches at 1550–1800 m
a.s.l. and Sub-zone 5B, Cyathea loheri –Cephalomanes apiifolia patches at 1800–1875 m a.s.l. These pte-
ridophyte zones coincide with the woody species zones of Mt. Banahaw de Lucban but differ significantly
with the altitudinal fern zones of Mt. Makiling. Stepwise multiple regression analysis reveals that altitude
exhibits a linear relationship with pteridophyte species distribution. Altitude and soil pH influence 65% of
the variation in principal component 1 [PC1 = 0.0839 + 0.0010(altitude) 0.2072(soil pH); r= 0.8058]
and 27% of the variation in principal component 2 [PC2 = 2.0453 0.0005(altitude) 0.2560(soil pH);
r= 0.5206]. Thirty-three (33) species are preferential to specific microenvironments along the altitudinal
gradient, making them effective altitudinal zone markers and biodiversity conservation indicators for the
forest ecosystem of Mt. Banahaw de Lucban.
Introduction
A common approach in classifying vegetation is by
dividing it to segments named after the dominant
plant species. In tropical mountains, these seg-
ments can be observed as distinct altitudinal veg-
etation zones (Whitmore 1975; Van Steenis 1984;
Richards 1996). Ohsawa and co-workers (1985,
1986, 1987, 1991, 1993) with Kitayama (1992)
studied and compared the altitudinal zones of the
Himalayas, Southeast Asia and South and East
Asia. These series of studies contributed to a better
understanding of the vertical structure of vegeta-
tion along latitudinal gradients in Asia.
In the Philippines, Brown (1919) worked on the
zonation of Mt. Makiling and recognized four
zones namely; (a) Parang zone at 0–200 m a.s.l.;
(b) Dipterocarp forest zone at 200–600 m a.s.l.; (c)
Mid-mountain forest zone at 600–900 m a.s.l. and
(d) Mossy forest zone at 900–1140 m a.s.l. On the
Plant Ecology (2005) 180: 135–151 Springer 2005
DOI 10.1007/s11258-004-2494-7

other hand, Buot and Okitsu (1998) established
four vegetation zones in the montane forest of
Mt. Pulog, Luzon Island’s highest mountain peak
located in the Cordillera mountain range. These
are: (a) Pinus forest zone at 2000–2300 m a.s.l.; (b)
Pinus-Deutzia-Schefflera forest zone at 2300–
2400 m a.s.l.; (c) Lithocarpus-Dacrycarpus-Syzy-
gium-Leptospermum forest zone at 2400–2600 m
a.s.l. and (d) Rhododendron-Clethra-Eurya forest
zone at 2600–2700 m a.s.l.
The dominant families of vascular plants at
different altitudes of Mt. Banahaw de Lucban and
its neighboring massif, Mt. Banahaw have been
reported in unpublished literatures (Aragones
1991; Faller 1991; Esperanza 1993; Caguioa 1997;
Guttierez 1997).
The aforementioned studies however, are focused
on woody tree species only. This underestimates the
role of pteridophytes as altitudinal zone markers
despite their being a prominent component of
tropical mountain ecosystems. Very few altitudinal
studies on pteridophytes have been conducted. Ba-
naticla and Buot (2004) studied pteridophyte species
diversity and patch structure along the altitudinal
gradient of Mt. Banahaw de Lucban while Espinas
(2003) classified four altitudinal fern zones on the
midmontane forest of the Mt. Makiling.
Up to the present, the altitudinal zonation of
pteridophytes in Mt. Banahaw de Lucban has not
been studied. This is critical since the said moun-
tain is a part of Mt. Banahaw National Park, a
biodiversity hotspot and one of the country’s cen-
ters of plant diversity (Mittermeier et al. 1997; Ong
et al. 2002). To address this need, a study on the
altitudinal gradient distribution of ferns and fern
allies on Mt. Banahaw de Lucban was conducted.
This is a pioneering taxonomic and ecological work
in the Philippines, which establishes the ecological
zones of fern vegetation at various altitudes.
This study primarily aims to determine the pat-
tern of pteridophyte distribution along altitudinal
gradient of the northeastern slope of Mt. Banahaw
de Lucban and its relationship with environmental
factors such as elevation, soil and others.
Study area
Mt. Banahaw de Lucban towers at 1875 m a.s.l.
and lies in the northeastern portion of the Mts.
Banahaw–San Cristobal National Park (Figure 1).
This conical peak covers a total land area of
1166 ha. The other two peaks that form the said
mountain complex are Mt. San Cristobal (1470 m
a.s.l.) and Mt. Banahaw (2140 m a.s.l.). The study
was specifically conducted at the northeastern
slope of Mt. Banahaw de Lucban and covered the
altitudinal range from 700 m a.s.l., where the
vegetation is disturbed by agricultural activities,
up to the summit (1875 m a.s.l.), where the natural
vegetation is intact and well protected (Figure 1).
The topography of the mountain is character-
ized by moderate to steep terrain. The soil within
the vicinity is classified as Luisiana sandy clay
loam while the climatic regime falls under type II
climate, marked by the absence of a distinct dry
season. Mean annual temperature recorded from
1971 to 2000 in Tayabas, Quezon at 157.7 m a.s.l.,
is 26.5 C with a mean minimum temperature of
23.1 C and a mean maximum temperature of
29.9 C (Figure 2). Mean annual rainfall recorded
in the same weather station within the same
30-year period is 3152.8 mm while mean relative
humidity is 85% (PAGASA 2000).
Methods
Field methods
Patches of fern vegetation along the altitudinal
gradient were identified based on the homogeneity
of the existing plant communities particularly those
dominated by pteridophyte species. Each patch
was considered as a sampling site. In cases where
no distinct fern patches were observed within at
least 100 m elevation range, vegetation patches
with considerably many pteridophyte species in it
were selected as sample. A total of forty-two (42)
sampling sites were determined (Figure 1).
For each sampling site, a transect line varying
from 10 to 20 m depending on the homogeneity
and size of the patch was set following the line
intercept technique (Greig-Smith 1957). All the
pteridophyte species found intercepting the tran-
sect line were listed and their cover (C) or intercept
length was measured. The transect number, sam-
pling date and the measurements obtained were
recorded. Exposure was determined using compass
bearing. Altitude and geographic location were
measured using a geographic positioning system
(GPS) device and slope was determined by
136

14 04
’
12131
’
12130
’
’
14 05
33
34
36
35 37
38 32
39
40 31
26
25
24
23 22
21
20
17
19 18
1
15
16
14
13 12
30
87
9
65
42
4
2
11
3
10 41
27
28
29
x
Camp House
1500
1700
1600
1800
1875
732
700
808
800
900
1000
600
749
1100
500 m0
Mt.Banahaw de luckban
(1875m)
Figure 1. Location map of the 42 transect lines in the study area. The inset shows the location of Mt. Banahaw de Lucban in the
Philippines.
137

estimating the angle between the ground and a
wooden stick perpendicularly pegged into it.
Composite random soil samples were taken from
the topsoil (up to 10 cm below ground) for each
sampling site. Each soil sample was analyzed for
pH, soil texture and organic matter content.
Voucher specimens were collected for each spe-
cies. The unknown specimens were then identified
at the herbarium of the University of the
Philippines Los Ban
˜os (CAHUP) and the Philip-
pine National Herbarium (PNH). Copelands’ Fern
Flora of the Philippines (1958–1961) and Series II
of Flora Malesiana (1959–1998) were primarily
used as reference in species identification. Different
authors were consulted for the taxonomic treat-
ment of each family (Holttum 1959, 1963, 1978,
1981, 1991; Kramer 1971; Hovenkamp 1998;
Nooteboom 1998).
Data analysis
For this study, cover (C) was considered as the
measure of dominance. To determine the exact
number of dominant species objectively, the cover
values obtained for each patch were subjected to
dominance analysis of Ohsawa (1984) using the
equation:
d¼1
NX
i2Tðxi
xÞ2þX
j2U
x2
j
where dis the deviation, x
i
is the actual percent
share [in this case, the cover values (C)] of the top
species (T), i.e., the top dominant in the
one-dominant model, or the two top dominants in
the two-dominant model, and so on, 
xis the ideal
percent share based on the aforementioned model,
x
j
is the percent share of the remaining species (U),
and Nis the total number of species.
The cover values (C) were also used for cluster
analysis and ordination. Each line transect was
compared pairwise by computing for the Sørensen
coefficient defined as follows:
Ss¼2a
2aþbþc
where S
s
is Sørensen coefficient of similarity, ais the
number of species common to both transects, bis the
number of species in transect 1 and cis the number
of species in transect 2. A similarity matrix for all the
line transects was prepared. This was then subjected
to hierarchical cluster analysis and principal com-
ponent analysis (PCA) using the SPSS software.
The outputs were a dendogram constructed by
average linkage clustering using the squared
Euclidean distance and a two-dimensional compo-
nent plot based on the two principal components.
PCA summarized the overall variation among
transects by extracting two principal components
from the similarity matrix. The component scores of
each transect were then plotted using the two prin-
cipal components as the ordination axes. The points
in the component plot represent transects while the
distances between the points reflect their similarity
or dissimilarity. Thus transects with similar species
composition would tend to form a cluster.
JFMAMJ JASOND
0
20
100
200
300
400
Cmm
500
600
Tayabas, Quezon (157.7m)
(30 - 30)
3152.826.5
0
10
20
40
60
80
30
Figure 2. Climogram for Tayabas, Quezon, the nearest weather station to Mt. Banahaw de Lucban.
138

Multiple regression analysis was applied using
the equation:
Y¼b0þb1X1þb2X2þþbqXq
where Y= the dependent variable; X
1
,X
2
,…,
X
q
= the independent variables and b
0
,b
1
,b
2
,…,
b
q
= the partial regression coefficients of the inde-
pendent variables. In order to determine the factors
that mainly affect the pattern of pteridophyte dis-
tribution suggested by PCA and cluster analysis, the
two principal components (PC1 and PC2) were used
as the dependent variable (Y) while elevation, soil
pH, soil organic matter and slope were used as
independent variables (X
1
,X
2
,X
3
,X
4
respectively).
Results
Species composition
A total of 93 pteridophyte species (including 10
varieties) representing 47 genera and 24 families
were found within the study area (Table 1), 89%
(83 spp.) of which were ferns while the rest were
fern allies (10 spp., 2 genera, 2 families). Seventy-
four (74) species were encountered in transects
while the remaining 19 were found outside tran-
sects but were listed for the sake of documentation.
The most represented families were Hymeno-
phyllaceae (11 spp.), Polypodiaceae (11 spp.), and
Aspleniaceae (9 spp.) while the most represented
genera were Asplenium (9 spp.), Lycopodium (5
spp.) and Selaginella (5 spp.) followed by Cyathea,
Cephalomanes,Diplazium,Lindsaea and Microso-
rum each with four species.
Altitudinal zones
Hierarchical cluster analysis revealed a dendro-
gram (Figure 3) portraying the relationship among
the 42 transects classifying six clusters at a squared
Euclidean distance of 17. Each cluster was desig-
nated as a zone. The two narrow clusters at the
lowest portion of the dendrogram represented
transects located in moderately to highly disturbed
and exposed areas at lower elevations with the
exception of outlier transect 1 which was located at
1158 m a.s.l. Considering their proximity and
expected variability in species composition due to
Table 1. List of pteridophyte species found in Mt. Banahaw de
Lucban and their total cover values for the 42 transects.
Family/Species Total cover
values (cm)
a
Adiantaceae
Coniogramme fraxinea(Don) Diels.? 420
Aspleniaceae
Asplenium affine Sw. ? –
Asplenium cymbifoliumChrist 2606
Asplenium lepturus J. Sm. ex Presl 32
Asplenium perscicifolium J. Sm. 421
Asplenium phyllitidis Don. –
Asplenium polyodon Forst. –
Asplenium tenerum G. Forst. 809
Asplenium unilaterale Lam. –
Asplenium vulcanicum Bl. 103
Athyriaceae
Deparia petersenii (Kunze) M. Kato var.
petersenii
–
Diplazium cultratum C. Presl 40
Diplazium esculentum (Retz.) Sw. 900
Diplazium polypodioides Bl. 500
Diplazium williamsii Copel. 257
Blechnaceae
Blechnum egregium Copel. –
Blechnum fraseri (A. Cunn.) Luerss. 315
Blechnum orientale L. 295
Cyatheaceae
Cyathea callosa Christ 7778
Cyathea contaminans (Wall. ex Hook.)
Copel.
2674
Cyathea loheri Christ 3652
Cyathea philippinensis Bak. 4235
Dicksonia mollis Holttum 300
Davalliaceae
Davallia hymenophylloides(Blume) Kuhn 1025
Davallia solida (G. Forst.) Sw. 10
Dennstaedtiaceae
Histiopteris incisa (Thunberg) J. Sm. 823
Microlepia speluncae (L.) Moore –
Dipteridaceae
Dipteris conjugata Reinw. –
Dryopteridaceae
Arachniodes tripinnata (Goldm.) Sledge –
Dryopteridaceae
Polystichum horizontale C. Presl. 501
Gleicheniaceae
Dicranopteris linearis var. latilobaHolttum 2362
Dicranopteris linearis(Burm. f.) Underw. var .
linearis
602
Gleichenia hirta Bl. 560
Gleichenia longissima Bl. 300
Grammitidaceae
Calymmodon gracilis (Fee) Copel. 367
Grammitis jagoriana (Mett.) Copel. 120
Prosaptia celebica (Bl.) Tagawa & K. Iwats. 231
Hymenophyllaceae
Cephalomanes apiifolia (C . Presl) K. Iwats. 1537
139

man-made disturbances, these two clusters were
fused into Zone 1 consequently reducing the main
clusters into five zones. Expectedly because of their
adjacent locations, Zones 2 and 3 were more flo-
ristically similar to each other than to all the other
zones. Zones 4 and 5 exhibited the same relation-
ship.
PCA revealed six clusters (Figure 4) as in the
cluster analysis (Figure 3). However, the main
difference was the separation of Zone 5 into 2
distinct clusters (Sub-zone 5A and Sub-zone 5B)
(Figure 4), owing to differences in elevation range
and dominant species. The strong affinity of Zone
2 with Zone 3 is confirmed by the proximity of
their clusters in the principal component plot
(Figure 4). Transect 11 probably represented a
patch intermediate of these two zones. Five outlier
transects were detected namely transects 1, 7, 8, 25
and 30. Transects 1 and 28 were located in open
areas in higher elevations while transects 7 and 8
were located respectively in a ravine and in a
Pandanus-dominated forest patch. Transect 30 was
along the roadside at 709 m a.s.l.
Cluster analysis, PCA and field observations
therefore supported the classification of pterido-
phyte vegetation into five zones as follows: Zone 1,
Cyathea contaminans – Dicranopteris–Nephrolepis–
Table 1. Continued.
Family/Species Total cover
values (cm)*
Cephalomanes atrovirens C. Presl 10
Cephalomanes meifolia (Bory) K. Iwats. 1351
Cephalomanes obscurum (Bl.) K. Iwats. var.
obscurum
796
Crepidomanes acutum (C.Presl) K. Iwats. –
Crepidomanes cumingii (C. Presl) K. Iwats. 90
Crepidomanes pallidum (Bl.) K. Iwats. 25
Hymenophyllum badium H.K. & Grev. 30
Hymenophyllum meyenianum (C. Presl) Copel. 1273
Hymenophyllum polyanthos (Sw.) 299
Hymenophyllum sp. –
Lindsaeaceae
Lindsaea fissa Copel. 816
Lindsaea obtusa J. Sm. 241
Lindsaea pulchella (J. Sm.) Mett. ex
Kuhn.var. pulchella
97
Lindsaea repens (Bory) Thwaites var.
pectinata
164
Sphenomeris chinensis var. divaricata(Christ)
Kramer
–
Tapeinidium luzonicum (Hook.) Kramer 507
Tapeinidium luzonicum var. leptophyllum
Kramer
–
Tapeinidium pinnatum (Cav.) C. Christ 42
Lomariopsidaceae
Bolbitis sinuata (C. Presl) Hennip. 90
Bolbitis rhizophylla (Kaulf.) Hennip. 363
Elaphoglossum luzonicum Copel. 128
Lycopodiaceae
Lycopodium carinatum Desv. –
Lycopodium cernuum L. 247
Lycopodium phleghmaria L. 38
Lycopodium piscium (Herter) Tagawa &
K. Iwats.
–
Lycopodiaceae
Lycopodium squarrosum G. Forst. –
Marattiaceae
Angiopteris palmiformis (Cav.) Christ 1391
Oleandraceae
Nephrolepis cordifolia (L.) Presl 408
Nephrolepis hirsutula (Forst.) Presl 1585
Oleandra maquilingensis Copel. 520
Ophioglossaceae
Ophioglossum reticulatum L. –
Plagiogyriaceae
Plagiogyria pycnophylla (Kunze) Mett. 785
Polypodiaceae
Goniophlebium perscicifolium (Desv.) Bedd. 313
Goniophlebium pseudoconnatum (Copel.)
Copel.
100
Goniophlebium subauriculatum (Bl.) Presl 393
Lemmaphylum accendens (Bl.) Donk. 375
Leptochillus macrophyllus (Bl.) Noot. var.
macrophyllus
44
Microsorum heterocarpum (Bl.) Ching 288
Microsorum insigne (Blume) Copel. 496
Microsorum membranifolium (R. Br.) Ching –
Microsorum punctatum (L.) Copel. 97
Pyrrosia sp. 26
Selliguea taeniata Copel. 1118
Selaginellaceae
Selaginella cumingiana Spring 3048
Selaginella cupressina (Willd.) Spring 1344
Selaginella delicatula (Desv.) Alston. 6900
Selaginella engleri Hieron. –
Selaginella uncinata (Desv.) Spring 288
Tectariaceae
Pleocnemia cumingiana Presl –
Pleocnemia presliana Holtt. 360
Tectaria sulitii Copel. 478
Thelypteridaceae
Chingia ferox (Bl.) Holttum 340
Macrothelypteris torresiana (Gaud.) Ching 167
Christella subdentata (Forssk.) Browsey &
Jermy
1113
Sphaerostephanos hirsutus (Kunze ex Mett.)
Holtt.var. hirsutus
4721
Vittariaceae
Anthrophyum reticulatum (Forst.) Kaulf. –
Vittaria crispo-marginata Christ 366
a
Species without cover values were found outside transects.
140

Diplazium patches from 700 to 800 m a.s.l.; Zone
2,Sphaerostephanos hirsutus – Selaginella delica-
tula patches from 750 to 900 m a.s.l.; Zone 3,
Cyathea philippinensis – Selaginella patches from
900 to1200 m a.s.l.; Zone 4,Cyathea philippinensis
– Cyathea callosa–Asplenium cymbifolium–Selagi-
nella cumingiana patches from 1200 to 1550 m
a.s.l. and; Zone 5 with Sub-zone 5A,Cyathea
callosa – Cyathea loheri-Hymenophyllaceae pat-
ches from 1550 to 1800 m a.s.l. and Sub-zone 5B,
Cyathea loheri –Cephalomanes meifolia patches
from 1800 to 1875 m a.s.l.
The fern zones proposed in this study are not
defined by clear-cut boundaries and do not exist as
extensive bands of vegetation. Adjacent zones like
Zone 2 and 3 even overlap at the edges. The zones
are named after the dominating taxa (Table 2).
These dominant fern species were quite prominent
as patches or stands but do not necessarily
dominate the whole forest community.
0
5
10152025
17
22
23
24
26
18
21
20
31
32
37
38
40
39
36
33
35
34
12
16
14
15
13
11
19
25
4
27
41
5
9
6
7
8
3
29
28
30
1
Elevation
(m.a.s.l.)
2
10
42
1296
1356
1394
1436
1500
1172
1284
1197
1530
1524
1722
1650
1570
1627
1771
1875
1826
1867
991
1147
1055
1097
1025
899
1184
1479
789
777
731
814
864
827
876
886
759
753
763
709
1158
762
757
782
ZONE 4
ZONE 5B
ZONE 3
ZONE 2
ZONE 1
Squared Euclidean Distance
Cyathea contaminans
Dicranopteris linearis
Nephrolepis hirsutula
Diplazium esculentum
Sphaerostephanos hirsutus var.
Selaginella delicatula
Cyathea philippinensis
Selaginella spp .
Cyathea callosa
Cyathea loheri
Hymenophyllaceae
Selaginella cumingiana
Cyathea callosa
Asplenium cymbifolium
Cyathea philippinensis
}
ZONE 5A
Cyathea loheri
Cephalomanes meifolia
}
Figure 3. Dendrogram of the 42 transects constructed by average linkage clustering using the SPSS software. Five zones were
identified: Zone 1 at 700–800 m a.s.l.; Zone 2 at 750–900 m a.s.l.; Zone 3 at 900–1200 m a.s.l.; Zone 4 at 1200–1500 m a.s.l.; Zone 5
divided into Sub-zone 5A at 1550–1800 m a.s.l. and Sub-zone 5B at 1800–1875 m a.s.l. (The dominant taxa for each zone are listed.
The encircled transects are outliers.
141

Zone 1. Cyathea contaminans – Dicranopteris–
Nephrolepis–Diplazium zone (700–800 m a.s.l.)
Transects 1, 2, 3, 10, 28, 29, 30 and 42 (Table 2)
were under this zone (Figure 3 and 4). All were
located within 700–800 m a.s.l. with the exception
of the outlier transect 1 (Figure 3) situated along
the bank of a dried creek at 1158 m a.s.l. This zone
was characterized by exposed, moderately to
highly disturbed areas such as mixed grassland and
brush land (parang), forest clearings, forest bor-
ders, riverbanks and roadsides. Soil was sandy
loam (silt loam in the forest border). Soil pH
ranged from 4.9 to 7.1 with a mean of 5.7 while
soil organic matter (OM) ranged from 9.29 to
26.66% (Table 2).
The ‘fern zone’ does not refer to a continuous
mantle of pteridophyte vegetation but to a mosaic
of three distinct fern patches scattered within the
area: (1) Patches of Cyathea contaminans in forest
borders and thickets of Dicranopteris spp. partic-
ularly Dicranopteris linearis var. latiloba are more
dominant in exposed areas, (2) Strips of Nephrol-
epis hirsutula in grasslands and in forest edges, and
(3) Small to vast beds of Diplazium esculentum
scattered within the mixed grassland/brush land
vegetation at the foot of the slope.
Zone 2. Sphaerostephanos hirsutus – Selaginella
delicatula zone (750–900 m a.s.l.) The Sphaero-
stephanos hirsutus–Selaginella delicatula zone was
represented by transects 4, 5, 6, 7, 8, 9,27 and 41
(Figures 3–4 and Table 2) located at 750–900 m
a.s.l. with the exception of patch 41, in a forest
fragment at 731 m a.s.l. Outlier transects 7 and 8
(Figure 4) were located in a ravine at 876 m a.s.l.
and a Pandanus dominated forest patch at 886 m
a.s.l. respectively. Soil was primarily sandy loam
while soil pH and soil OM ranges from 4.7 to 5.5
and from 8.24 to 32.91% respectively (Table 2).
Patches of Selaginella delicatula were sur-
mounted by a continuous mantle of Sphaero-
stephanos hirsutus and Christella subdentata that
extended up to 10 m from each side of the trail.
Large individuals of Angiopteris palmiformis also
occurred sporadically. Considering the other four
1.0.50.0-.5-1.0
1.0
.5
0.0
-.5
-1.0
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25 24
23
22
21
20
19
18
17
16
15 1413
12
11
10
9
8
7
6
5
4
32
1
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5A
Zone 5B
PC2 = 2.0453 - 0.0005(altitude) - 0.2560(soil pH)
PC11= 0.0839+0.0010(altitude) - 0.2072(soil pH)
Figure 4. Component plot of the 42 transects obtained by PCA using the SPSS software. Six clusters were observed corresponding to:
Zone 1, Cyathea contaminans –Dicranopteris–Nephrolepsis–Diplazium patches at 700–800 m a.s.l.; Zone 2, Sphaerostephanos hirsutus –
Selaginella delicatula patches at 750–900 m a.s.l.; Zone 3, Cyathea philippinensis –Selaginella patches at 900–1200 m a.s.l.; Zone 4,
Cyathea philippinensis – Cyathea callosa–Asplenium cymbifolium–Selaginella cumingiana patches at 1200–1550 m a.s.l.; Zone 5A,
Cyathea callosa – Cyathea loheri-Hymenophyllaceae at 1550–1800 m a.s.l. and Zone 5B, Cyathea loheri – Cephalomanes meifolia
patches at 1800–1875 m a.s.l. Transects 1, 7, 8, 25 and 30 are outliers.
142

Table 2. General information and dominant species of the 42 transects. The dominant species are determined by Ohsawa dominance analysis of Ohsawa (1984).
Transect
no.
Date
sampled
Transect
length (m)
Location Altitude
(m)
Exposure Slope
()
Temperature
(C)
Relative
humidity
(%)
Soil data
a
Dominant species
Texture pH % OM
1 3-Mar-02 10 1405¢24 N; 12131¢08 E 1158 S52W 20 18 91 sandy clay
loam
7.1 15.33 Cyathea contaminans–Gleichenia hirta
2 3-Mar-02 10 1406¢02 N; 12131¢26 E 762 S60E 10 18 70 sandy loam 5.5 26.66 Nephrolepis hirsutula
3 3-Mar-02 10 1406¢02 N; 12131¢26 E 759 S5W 12 16 70 sandy loam 5.1 25.74 Dicranopteris linearis var. latiloba
4 4-Mar-02 10 1405¢56 N; 12131¢23 E 789 S24E 5 17 86 sandy loam 4.8 27.42 Sphaerostephanos hirsutus var. hirsutus–
Selaginella delicatula
5 4-Mar-02 20 1405¢53 N; 12131¢18 E 814 S16E 22 17 75 sandy loam 4.9 25.94 Sphaerostephanos hirsutus var. hirsutus–
Selaginella delicatula
6 4-Mar-02 20 1405¢47 N; 12131¢14 E 864 S29W 30 18 82 sandy loam 4.8 10.33 Selaginella delicatula–Cyathea contaminans
7 4-Mar-02 10 1405¢45 N; 12131¢13 E 876 S43E 60 18 82 sandy loam 4.7 8.24 Coniogramme fraxinea ?–Nephrolepis cordifolia
8 4-Mar-02 10 1405¢44 N; 12131¢10 E 886 S5E 15 18 91 sandy loam 4.8 20.68 Cyathea callosa –Davallia hymenophylloides
9 4-Mar-02 10 1405¢49 N; 12131¢15 E 827 S75E 30 18 91 sandy loam 5 14.1 Sphaerostephanos hirsutus var. hirsutus–
Asplenium tenerum
10 4-Mar-02 10 1406¢03 N; 12131¢28 E 757 S60E 10 18 84 sandy loam 4.9 18.98 Nephrolepis hirsutula
11 5-Mar-02 10 1405¢40 N; 12131¢08 E 899 S253W 7 18 91 sandy loam 4.8 31.38 Selaginella cupressina–Selaginella delicatula
12 5-Mar-02 10 1405¢35 N; 12131¢07 E 991 S3E 45 18 91 sandy loam 4.5 35.3 Cyathea philippinensis–Selaginella cumingiana
13 5-Mar-02 10 1405¢31 N; 12131¢07 E 1025 S248W 2 19 82 sandy loam 4.7 38.69 Cyathea philippinensis–Selaginella delicatula
14 5-Mar-02 10 1405¢30 N; 12131¢07 E 1055 N25E 55 20 91 sandy loam 4.5 42.37 Cyathea philippinensis–Selaginella delicatula
15 5-Mar-02 20 1405¢28 N; 12131¢07 E 1097 S198W 20 22 95 sandy loam 4.8 20.57 Cyathea philippinensis–Selaginella delicatula
16 5-Mar-02 10 1405¢24 N; 12131¢07 E 1147 N304W 3 19 95 sandy loam 5.3 19.17 Cyathea philippinensis
17 5-Mar-02 10 1405¢13 N; 12131¢02 E 1296 N305W 5 17 95 sandy loam 5.2 16.18 Cyathea callosa–Asplenium cymbifolium
18 6-Mar-02 20 1405¢22 N; 12131¢05 E 1172 N19E 5 18 91 sandy loam 4.4 13.48 Cyathea callosa–Selaginella cumingiana
19 6-Mar-02 10 1405¢17 N; 12131¢03 E 1184 S3E 25 18.5 96 sandy loam 4.7 19.52 Asplenium cymbifolium–Selaginella delicatula
20 6-Mar-02 10 1405¢15 N; 12131¢03 E 1197 S224W 5 18 74 sandy loam 4.6 42.03 Cyathea callosa–Selaginella cumingiana
21 6-Mar-02 10 1405¢13 N; 12131¢03 E 1284 S262W 45 19 91 sandy loam 4.8 41.08 Cyathea callosa
22 6-Mar-02 10 1405¢09 N; 12131¢00 E 1356 S164E 30 18 95 sandy loam 5.2 19.63 Cyathea callosa–Asplenium cymbifolium
23 6-Mar-02 20 1405¢05 N; 12130¢59 E 1394 N300W 45 15 91 loamy sand 5 39.79 Cyathea callosa–Asplenium cymbifolium
24 7-Mar-02 10 1405¢03 N; 12130¢59 E 1436 S238W 50 16 90 sandy loam 5.1 28.7 Cyathea callosa–Cyathea philippinensis
25 7-Mar-02 10 1404¢59 N; 12130¢59 E 1479 S244E 45 14 100 sandy loam 4.8 30.36 Cyathea philippinensis–Hymenophyllum
polyanthos
26 7-Mar-02 10 1404¢55 N; 12130¢58 E 1500 S237W 20 13 100 sandy loam 4.4 22.04 Cyathea philippinensis–Cephalomanes apiifolia
27 7-Mar-02 10 1405¢59 N; 12131¢25 E 777 N300W 6 16 91 loamy sand 5.1 32.91 Sphaerostephanos hirsutus var. hirsutus –
Selaginella delicatula
28 7-Mar-02 10 1406¢02 N; 12131¢27 E 763 S127E 3 17 86 silt loam 5.3 13.85 Dicranopteris linearis var. latiloba–Cyathea
contaminans
29 16-Mar-02 10 1406¢07 N; 12131¢33 E 753 S62W 2 21 68 sandy loam 5.5 9.29 Dicranopteris linearis var. latiloba–Cyathea
contaminans
30 16-Mar-02 10 1406¢12 N; 12131¢41 E 709 S207W 2 26 64 loamy sand 7.2 5.97 Sphaerostephanos hirsutus var. hirsutus–
Histiopteris incisa
31 17-Mar-02 10 1404¢54 N; 12130¢58 E 1530 S248W 55 18 85 sandy loam 5 41.78 Cyathea callosa
32 17-Mar-02 10 1404¢53 N; 12130¢58 E 1524 S260W 55 17 90 loamy sand 5 38.21 Cyathea callosa–Cyathea contaminans
33 17-Mar-02 10 1404¢34 N; 12130¢49 E 1875 N291W 2 15 100 sandy loam 5.7 20.45 Cyathea loheri
34 18-Mar-02 10 1404¢34 N; 12130¢47 E 1867 S223W 25 13 100 sandy loam 5 71.69 Cyathea loheri–Cephalomanes meifolia
143

zones that exhibited patchy fern distribution, Zone
2 truly formed a ‘zone’ in the strict sense, domi-
nating the understorey of the secondary forest
from 751 to 820 m a.s.l. as a continuous mantle of
fern vegetation. At 820–900 m a.s.l., this fern un-
derstorey was becoming sparse and larger flower-
ing tree species began to dominate the forest
community. Epiphytes like Microsorum spp.,
Asplenium tenerum,Vittaria crispo-marginata,
Pyrrosia sp., and Lemmaphylum accendens were
more conspicuous.
Zone 3. Cyathea philippinensis-Selaginella zone
(900–1200 m a.s.l.) Transects 11, 12, 13, 14, 15, 16,
19 and 25 (Figures 3–4 and Table 2) were under
this zone ranging from 900 to 1200 m a.s.l. except
for the outlier transect 25 situated on a fallen log
at 1479 m a.s.l. This altitudinal range was still
covered by secondary forest. Fern vegetation
continued to be relatively sparse, existing as
irregularly scattered patches within the forest
undergrowth. Soil was sandy loam (Table 2) and
soil pH ranged from 4.5 to 5.3 with a mean of 4.76
while soil OM ranged from 19.17 to 42.37%.
This zone was characterized by small to medium-
sized stands (composed of 3–10 individuals) of
Cyathea philippinensis occasionally dominating the
understorey. A few trees of Cyathea callosa also
started to appear within this zone. Pure and mixed
patches of Selaginella delicatula,Selaginella cumin-
giana and Selaginella cupressina occurred intermit-
tently along trails and in small openings. Epiphytes
growing in pure and mixed stands (e.g. Lycopodium
phlegmaria,Oleandra maquilingensis and Cepha-
lomanes apiifolia) continued to flourish in this zone.
Zone 4. Cyathea philippinensis – Cyathea callosa–
Asplenium cymbifolium–Selaginella cumingiana
zone (1200–1550 m a.s.l.) This heterogenous zone
was represented by transects 17, 18, 20, 21, 22, 23,
24, 26, 31 and 32 (Figures 3–4 and Table 2) com-
posed of fern patches irregularly distributed from
1200 to 1550 m a.s.l. The upper portion of this zone
(1400–1550 m a.s.l.) was rather exposed and dom-
inated by rattan species (Calamus spp.). Neverthe-
less, it appeared to be a zone of development for
tree ferns. The shift of dominance from Cyathea
philippinensis to Cyathea callosa and the lower limit
appearance of Cyathea loheri can be observed in
this zone. Individuals of the two other tree fern
species –Cyathea contaminans and Dicksonia mollis
were also spotted in this zone. Soil was mainly
sandy loam (loamy sand for transect 23). Soil pH
Table 2. Continued.
Transect
no.
Date
sampled
Transect
length (m)
Location Altitude
(m)
Exposure Slope
()
Temperature
(C)
Relative
humidity
(%)
Soil data* Dominant species
Texture pH % OM
35 18-Mar-02 10 1404¢37 N; 12130¢51 E 1826 S211W 55 14 100 sandy loam 4.8 30.5 Cyathea loheri
36 18-Mar-02 10 1404¢41 N; 12130¢53 E 1771 S224W 55 16 71 sandy loam 5 45.69 Cyathea callosa–Cephalomanes apiifolia
37 18-Mar-02 15 1404¢43 N; 12130¢54 E 1722 S119E 8 15 95 sandy loam 4.7 18.92 Cyathea loheri–Hymenophyllum meyenianum
38 18-Mar-02 20 1404¢46 N; 12130¢55 E 1650 S194W 45 16 95 silt loam 5.2 31.64 Cyathea callosa–Cyathea loheri
39 18-Mar-02 10 1404¢48 N; 12130¢55 E 1627 S214W 30 13 95 loamy sand 5 30.48 Cyathea callosa–Hymenophyllum meyenianum
40 18-Mar-02 10 1404¢52 N; 12130¢58 E 1570 S232W 45 11 100 loamy sand 5 20.06 Cyathea callosa–Cyathea loheri
41 19-Mar-02 20 1406¢04 N; 12131¢30 E 731 S34W 9 20 91 sandy loam 5.5 13.76 Selaginella delicatula–Angiopteris palmiformis
42 19-Mar-02 10 1406¢01 N; 12131¢21 E 782 S4W 2 19.5 96 sandy loam 5.2 15.26 Diplazium esculentum
a
Analyzed at the Analytical Services Laboratory, Department of Soil Science, UPLB. Percentage of soil OM was obtained using the Walkley-Black Method.
144

ranged from 4.4 to 5.2 with mean of 4.87 while soil
OM ranged from 16.18 to 42.03% (Table 2).
Five distinct fern patches were observed: (1)
Strips of Selaginella cumingiana along trails at
1200–1300 m a.s.l. ; (2) Pure stands of C. philip-
pinensis from 1200 to 1300 m a.s.l.; (3) Mixed
C. philippinensis–C. callosa stands occasionally
distributed throughout the elevation range; (4)
Pure stands of C. callosa from 1300 to 1550 al-
though individuals of C. philippinensis and C. loheri
also occurred within this range; (5) Clusters of the
epiphyte Asplenium cymbifolium from 1300 to
1400 m a.s.l. This zone was also marked by a
moderate change in species composition of epi-
phytes with Cephalomanes apiifolia and Lindsaea
spp. starting to occur more frequently.
Zone 5. Cyathea callosa–Cyathea loheri-
Hymenophyllaceae zone (1550–1875 m a.s.l.) This
zone was covered by the mossy forest dominated by
Podocarpus spp., Dacrycarpus spp. and the epiphytic
Freycinettia spp. Hedyotis spp. occupied the under-
storey while bryophytes covered tree trunks, rocks
and other wet and shaded surfaces. Soil ranged from
loamy sand to sandy loam and silt loam (Table 2).
Soil pH ranged from 4.7 to 5.7 with a mean of 5.05
and soil OM ranged from 20.45 to 71.69%.
This shift of tree fern dominance from Cyathea
callosa to Cyathea loheri and the abundance of
Hymenophyllaceae species (filmy ferns) in the
undergrowth were prominent in this zone which
could be divided into two sub-zones. Transects 36,
37, 38, 39 and 40 (Figure 4 and Table 2) were
classified under Sub-zone 5A which ranged from
1550 to 1800 m a.s.l. This sub-zone corresponded
to the mixed stands of C. callosa and C. loheri and
patches of filmy ferns particularly Cephalomanes
apiifolia and Hymenophyllum meyenianum that
were distributed from 1550 to 1800 m a.sl. On the
other hand, Sub-zone 5B which is represented by
transects 33, 34 and 35 corresponded to the small
stands (3–5 individuals) of C. loheri and patches of
Cephalomanes meifolia found in small openings of
the forest understorey from 1800 to 1875 m a.s.l.
A few individuals of C. callosa were still observed
in this area.
Factors influencing Pteridophyte distribution
Results of the stepwise multiple regression analysis
(Figure 5) indicated that altitude and soil pH are
linearly related to pteridophyte species distribution
influencing 65% of the variation in principal
component 1[PC1 = 0.0839 + 0.0010(altitude) 
0.2072(soil pH); r= 0.8058] and 27% of the
variation in principal component 2 [PC2 =
2.0453–0.0005(altitude) 0.2560(soil pH); r=
0.5206].
The variation in species distribution represented
by PC1 appeared to be dictated by increasing
elevation (Figure 5a) and decreasing soil pH Fig-
ure 5c). On the other hand, the variation repre-
sented by PC2 seemed to be the result of
decreasing elevation Figure 5b). It also exhibited a
non-linear relationship with soil pH Figure 5d).
Discussion
Altitudinal zonation pattern of pteridophytes
on Mt. Banahaw de Lucban
The altitudinal zonation of pteridophytes pro-
posed in this study (Figure 6) agrees with the
altitudinal zonation of woody species reported by
Esperanza (1993). This implies that to some extent,
pteridophyte distribution is dependent on the
floristic composition and structure of woody veg-
etation along the slope. Zone 1 corresponds to the
mixed grassland/brushland (Parang) vegetation
zone at the foot of the slope. The patchy distri-
bution of pteridophytes is expected in this zone
because available fern habitats are only limited to
species tolerant to exposed and relatively drier
conditions such as Dicranopteris linearis,Histio-
pteris incisa and Diplazium esculentum. The
scrambling habit of the aforementioned species
gives them advantage in colonizing barren lands
and even dominating such open areas. Conse-
quently, this zone exhibited low pteridophyte
species diversity.
The lowland secondary forest of Mt. Banahaw
de Lucban encompasses Zone 2 and Zone 3. These
two fern zones are more spatially and floristically
related to each other than the other zones. Zone 2
corresponds to the more disturbed secondary for-
est where there is less forest cover and more open
condition, encouraging the growth of a Sphaero-
stephanos hirsutus– Selaginella delicatula under-
storey. The presence of this fern-dominated
undergrowth could have serious ecological impli-
cations in forest succession and regeneration.
145

-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
4 4.5 5 5.5 6.5 7 7.5
pH
Principal component2
30
1
33
29
41
28
16
17
38
27
39
36
34
31
22
23
9
4
19
6
18 8
11
13
14 7
12
26
20
37
15
25
35
10
5
40 24
342
21
-1
-0.5
0
0.5
1
4 4.5 5 5.5 6.5 7 7.5
pH
Principal component1
30
1
33
2
29
28
17
3
27
9
10
5
4
6
811 16
42
38
15
37
19
13
12
14
18 20 21 23
24
22
31
34
25
36
26 39
40
35
7
PC1 = 0.0839+0.0010(altitude) - 0.2072(soil pH)
r = 0.8058
PC2 = 2.0453-0.0005(altitude) - 0.2560(soil pH)
r = 0.5206
-1
-0.5
0
0.5
1
1.5
600 800 1000 1200 1400 1600 1800 2000
Altitude (m a.s.l.)
Principal Component1
30
1
34
35
33
36
37
38
39
40
31
32
25 26
24
23
22
21
17
20
19
18
16
15
14
8
12
13
11
6
5
9
4
42
27
228
3
29
41
10
PC1 = 0.0839 + 0.0010(altitude) - 0.2072(soil pH)
r = 0.8058
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
600 800 1000 1200 1400 1600 1800 2000
Principal component2
33
1
34
35
36
37
38
39
40
32
31
26
25
24
23
22
17
21
16
19
20
18
15
14
13
12
11
8
6
7
5
9
27
28
4
42
2
10
29
41
3
30
PC2 = 2.0453 - 0.0005(altitude) - 0.2560(soil pH)
r = 0.5206
Altitude (m a.s.l.)
6
6
(a)
(b)
(c)
(d)
Figure 5. Results of the stepwise multiple regression analysis showing: (a) positive linear relationship of PC1 and altitude; (b) negative
linear relationship of PC2 and altitude; (c) negative linear relationship of PC1 and soil pH; (d) non-linear relationship of PC2 and soil pH.
146

Understorey fern species are reportedly capable of
arresting forest succession and reducing species
diversity below the canopy by interfering with the
emergence and establishment of tree seedlings
(George and Bazzaz 1999; Hill and Silander 2001).
Zone 3 on the other hand coincides with the less
disturbed secondary forest at higher elevations.
Epiphytes start to appear more frequently in this
zone as the availability of trellises (tree trunks and
branches) also increases.
Zone 4 coincides with the lower montane forest
which offers a variety of microenvironments for
various fern patches dominated by tree ferns
(Cyathea spp.), epiphytes (Asplenium cymbifolium)
and the herbaceous Selaginella cumingiana, Zone 5
corresponds to the upper montane/mossy forest
where the environmental conditions (constantly
low temperature and high relative humidity)
are favorable for the growth of filmy ferns
(Hymenophyllaceae).
Altitude (m a.sl.)
1875-
Woody Forest Zones
(Esperanza, 1993) Pteridophyte Zones
1550
Upper Montane/ Mossy Forest:
Podocarpaceae &
Fagaceae
ZONE 5
Cyathea callosa
Cyathea loheri
Hymenophyllaceae
1200-
Lower Montane Forest:
Myrtaceae & Lauraceae
ZONE 4
Cyathea philippinensis
Cyathea callosa
Asplenium cymbifolium
Selaginella cumingiana
ZONE 3
Cyathea philippinensis
Selaginella spp.
900-
Lowland Secondary Forest:
Myristicaceae & Meliaceae
ZONE 2: Sphaerostephanos hirsutus
Selaginella delicatula
700-
Mixed Grassland/Brushland Zone:
Euphorbiaceae & Moraceae
ZONE 1: Cyathea contaminans,
Dicranopteris, Nephrolepis &
Diplazium
600-
500-
( 700 m, Lowest Elevation of Mt. Banahaw de Lucban )
Agricultural Zone
200-
0-
( ca.450 m, Elevation of Lucban, Quezon)
Figure 6. Altitudinal zonation of ferns and woody species on the northeastern slope of Mt. Banahaw de Lucban.
147

Influence of altitude and other factors on the
pteridophyte zones
The strong linear relationship expressed by pteri-
dophyte distribution with elevation justifies the
designation of altitudinal pteridophyte zones
comparable to the forest zonation in the studies
mentioned earlier (Brown 1919; Whitmore 1975;
van Steenis 1984; Kitayama 1992; Richards 1996;
Buot and Okitsu 1998).
The altitudinal gradient is a complex one since it
carries with it changes in climatic, edaphic and
biotic factors. With increasing elevation, the
decrease in temperature and increase in precipita-
tion and relative humidity increases soil moisture
and slows down the rate of litter decomposition.
The latter condition results to increasing soil OM,
consequently decreasing soil pH as the amount of
organic acids increases. The topographic setting
becomes steeper and wind action increases with
altitude stunting the growth of tree species. The
plant community structure also changes with
altitude due to the climatic and soil gradient.
In Mt. Banahaw de Lucban, soil pH is primarily
acidic, fluctuating throughout the slope with values
ranging from highly acidic 4.4 to slightly basic 7.2
(Table 2). Soil surface texture is mainly sandy loam
with occasional patches of silt loam, loamy sand,
sandy clay loam while soil OM is generally high,
ranging from 5.97% at 709 m a.s.l. to 71.69% at
1867 m a.s.l. Such soil conditions are optimal for
the growth, development and reproduction of tree
ferns (Havananda 1998) and explain the persis-
tence of tree ferns species along the slope.
The remaining proportion of unexplained vari-
ations (PC1 – 35%; PC2 – 73%; Species diversity –
84%) may be caused by other environmental
factors that were neither sampled nor considered
in the regression analysis. Other potential factors
that can greatly influence altitudinal pteridophyte
zonation and species diversity are light conditions,
temperature and relative humidity, amount of
rainfall (Tang and Ohsawa 1997), soil type, soil
texture, soil moisture (Edwards et al. 1990), flo-
ristic composition and structure and abundance of
microclimates (Whitmore 1975; Sarmiento 1985;
Richards 1996).
In tropical mountains, as temperature decreases
with elevation, so does the leaf size of woody
species hence the appearance of distinct leaf
size zones that are distributed along the
altitudinal gradient (Whitmore 1975; Sarmiento
1985; Richards 1996; Buot and Okitsu 1999). Ki-
tayama (1992) was likewise able to explain the
influence of temperature to the zonal differentia-
tions on Mt. Kinabalu. However, no experimental
method for temperature was conducted in this
study to confirm the said generalization.
Based on their physiological responses to the
climatic zones along the altitudinal gradient, Faller
(pers. comm.) classified the forest tree species on
Mt. Banahaw de Lucban into microtherms (warm
adapted species from 650 to 1200 m a.s.l.) and
megatherms (cold adapted species from 1200 to
1875 m a.s.l.). Pteridophyte Zones 1–3 coincide
with the elevation range of the microtherms char-
acterized by warmer climate while Zones 4 and 5
coincide with the elevation range of the mega-
therms characterized by cooler and wetter climate.
Relative humidity is another possible determin-
ing factor for pteridophyte diversity and distribu-
tion. On Mt. Banahaw de Lucban, relative
humidity range from 71 to 100%. Such high values
of relative humidity are favorable for tree fern
development (Havananda 1998), hence the profuse
growth of Cyathea contaminans,Cyathea callosa,
Cyathea philippinensis and Cyathea loheri on
Mt. Banahaw de Lucban. However, no experi-
mental set-up was done in this study along this line.
Comparison with the altitudinal pteridophyte zones
of Mt. Makiling
The comparison of the altitudinal fern zones on
Mt. Banahaw de Lucban with that of Mt. Makil-
ing (Espinas 2003) is shown in Figure 7. The
dominant species and altitudinal range of the
pteridophyte zones on Mt. Makiling differ from
that of Mt. Banahaw de Lucban. The designated
zones in the former are also narrower in distribu-
tion.
This discrepancy is expected as Mt. Banahaw de
Lucban is higher than Mt. Makiling by 761 m. It
also faces the Pacific Ocean and is more exposed to
the northeast monsoon as compared with the latter
which is more situated inland. Nevertheless,
Nephrolepis sp. and Cyathea contaminans occur
within the same altitudinal range on the two
mountains. Another significant difference is the
species richness and abundance of tree ferns along
the altitudinal gradient of Mt. Banahaw de Lucban
148

probably due its environmental conditions (sandy
loam soil, high relative humidity) that are favor-
able for tree fern growth and reproduction.
Ferns as altitudinal zone markers
Thirty-three (33) species or 44.6% of the total 93
species were found to be preferential to only one
zone, qualifying them as effective altitudinal zone
markers (Table 3).
The altitudinal distribution of some of the
marker species of Zones 1–4 appears to be more
affected by light conditions and degree of distur-
bance rather than altitude such as Gleichenia hirta
and Gleichenia longissima found growing along the
creek at 1158 m a.s.l. and Selaginella uncinata,
Chingia ferox and Diplazium esculentum which are
1875- Mt. Banahaw de Lucban (1875 m)
1550-
ZONE 5
Cyathea callosa
Cyathea loheri
Hymenophyllaceae
1200-
ZONE 4
Cyathea philippinensis
Cyathea callosa
Asplenium cymbifolium
Selaginella cumingiana
Mt. Makiling (1114 m)
(Espinas, 2003)
900-
ZONE 3
Cyathea philippinensis
Selaginella Mossy Forest
ZONE 2: Sphaerostephanos hirsutus
Selaginella delicatula
700-
ZONE 1: Cyathea contaminans,
Dicranopteris,
Nephrolepis Diplazium
ZONE 4
Sphaerostephanos lobatus,
Nephroplepis acutangula,
Lomariopsis pteroides
ZONE 3: Nephrolepis acutangula Cyathea
contaminans Asplenium tenerum
600-
( 700 m, Lowest Elevation of
Mt. Banahaw de Lucban )
ZONE 2: Bolbitis heteroclita Bolbitis
rhizophylla Asplenium cuneatum
500-
Agricultural Zone
ZONE1: Ctenitis dissecta, Bolbitis heteroclita ,
Dryopteris sparsa
Lowland Forest
200-
0-
( ca.450 m, Elevation of Lucban, Quezon)
Parang Zone
Figure 7. Comparison of the altitudinal pteridophytes zones on Mt. Banahaw de Lucban and Mt. Makiling.
149

more limited to lower elevations. Marker species
of Zone 5 are mostly members of Hymenophyl-
laceae. The altitudinal distribution of these
filmy ferns is restricted to higher elevations where
there is constantly low temperature and high
moisture.
The altitudinal pteridophyte zones proposed in
this study can be used as reference for future
biodiversity monitoring programs in Mt. Banahaw
de Lucban. The preference of marker species to
specific microclimates could make them potential
indicators of the health of the forest ecosystem of
Mt. Banahaw de Lucban because they are
vulnerable even to the slightest change in their
habitat.
Acknowledgements
This study was funded by the Office of the Vice
Chancellor for Research and Extension of the
University of the Philippines Los Ban
˜os (OVCRE-
UPLB), the Southeast Asian Ministers of Educa-
tion Organization–Southeast Asian Regional
Center for Graduate Study and Research in
Agriculture (SEAMEO–SEARCA) and the
National Research Council of the Philippines
(NRCP). The authors would like to recognize the
valuable discussions with the following persons:
Dr Nestor T. Baguinon, Prof Danielo B. Tolentino
and Dr Norma O. Aguilar of UPLB; Dr Cecilia
Gascon of Southern Luzon Polytechnic College
(SLPC); Dr Julie F. Barcelona of the Philippine
National Herbarium (PNH) who also identified
majority of the specimens; Ms Mary Ann O.
Cajano of the Museum of Natural History
(MNH); Messrs Mario F. Nan
˜ola, Rolando G.
Juarez, Cesario C. Naynes, Butch Michael Maddul
and Howell A. Casacop.
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